FFH scientific research papers database
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2020 |
Milakin, K A; Gavrilov, N; Pašti, I A; Morávková, Z; Acharya, U; Unterweger, C; Breitenbach, S; Zhigunov, A; Bober, P Polyaniline-metal organic framework (Fe-BTC) composite for electrochemical applications Journal Article Polymer, 208 , 2020. @article{Milakin2020, title = {Polyaniline-metal organic framework (Fe-BTC) composite for electrochemical applications}, author = {K A Milakin and N Gavrilov and I A Pašti and Z Morávková and U Acharya and C Unterweger and S Breitenbach and A Zhigunov and P Bober}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090323515&doi=10.1016%2fj.polymer.2020.122945&partnerID=40&md5=be56e127fd0360a7e9ab7a1dde608c8a}, doi = {10.1016/j.polymer.2020.122945}, year = {2020}, date = {2020-01-01}, journal = {Polymer}, volume = {208}, abstract = {Polyaniline-metal organic framework (PANI/Fe-BTC) composites were prepared by oxidative polymerization of aniline in the presence of Fe-BTC, using various monomer:Fe-BTC ratios. Introduction of Fe-BTC into polyaniline-based materials led to significant reduction of their thermal stability starting from 2 wt% Fe-BTC content, which further decreased with decreasing monomer concentration in the initial reaction mixture. Fe-BTC being a low conducting component (2 × 10−10 S cm−1) in comparison to PANI (6 S cm−1) was found to negatively affect conductivity of PANI/Fe-BTC composites. Conductivity values gradually lowered with the decrease of aniline fraction in the polymerization mixture: from 4 S cm−1 for the composite prepared with 80 wt% of the monomer in the reaction mixture to 0.04 S cm−1 for the 20 wt% of the monomer. Decreasing aniline fraction during the materials preparation resulted in a smaller amount of PANI particles on the surface of Fe-BTC. When aniline concentration reached 20 wt%, the morphology of the composite was similar to the one of pristine Fe-BTC. These PANI particles were found to be mainly determining specific surface area of PANI/Fe-BTC composites due to the fact that specific surface area of the products decreased with decreasing monomer fraction from 55 m2 g−1 for pristine PANI to 8 m2 g−1 for PANI(20%)/Fe-BTC. XRD data showed that the composition of PANI(20%)/Fe-BTC material corresponds to a saturation point, after which aggregation of PANI chains occurs. Spectroscopic analysis revealed that PANI on the Fe-BTC interface is overoxidized and partially doped by Fe-BTC. These PANI-Fe-BTC interactions were found to affect electrochemical properties of the composites. Materials prepared using lower monomer fraction in the initial reaction medium were characterized by more favorable reduction transitions which happened at more positive potentials. Increasing aniline:Fe-BTC ratio was also found to enhance gravimetric capacitance of the composites, reaching 346 F g−1 at 20 mV s−1. Moreover, improved pseudo-Faradaic current response and substantially better reversibility during electrochemical characterization shown for PANI/Fe-BTC compared to pristine PANI can be advantageous for energy applications. © 2020 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polyaniline-metal organic framework (PANI/Fe-BTC) composites were prepared by oxidative polymerization of aniline in the presence of Fe-BTC, using various monomer:Fe-BTC ratios. Introduction of Fe-BTC into polyaniline-based materials led to significant reduction of their thermal stability starting from 2 wt% Fe-BTC content, which further decreased with decreasing monomer concentration in the initial reaction mixture. Fe-BTC being a low conducting component (2 × 10−10 S cm−1) in comparison to PANI (6 S cm−1) was found to negatively affect conductivity of PANI/Fe-BTC composites. Conductivity values gradually lowered with the decrease of aniline fraction in the polymerization mixture: from 4 S cm−1 for the composite prepared with 80 wt% of the monomer in the reaction mixture to 0.04 S cm−1 for the 20 wt% of the monomer. Decreasing aniline fraction during the materials preparation resulted in a smaller amount of PANI particles on the surface of Fe-BTC. When aniline concentration reached 20 wt%, the morphology of the composite was similar to the one of pristine Fe-BTC. These PANI particles were found to be mainly determining specific surface area of PANI/Fe-BTC composites due to the fact that specific surface area of the products decreased with decreasing monomer fraction from 55 m2 g−1 for pristine PANI to 8 m2 g−1 for PANI(20%)/Fe-BTC. XRD data showed that the composition of PANI(20%)/Fe-BTC material corresponds to a saturation point, after which aggregation of PANI chains occurs. Spectroscopic analysis revealed that PANI on the Fe-BTC interface is overoxidized and partially doped by Fe-BTC. These PANI-Fe-BTC interactions were found to affect electrochemical properties of the composites. Materials prepared using lower monomer fraction in the initial reaction medium were characterized by more favorable reduction transitions which happened at more positive potentials. Increasing aniline:Fe-BTC ratio was also found to enhance gravimetric capacitance of the composites, reaching 346 F g−1 at 20 mV s−1. Moreover, improved pseudo-Faradaic current response and substantially better reversibility during electrochemical characterization shown for PANI/Fe-BTC compared to pristine PANI can be advantageous for energy applications. © 2020 Elsevier Ltd |
Janićijević, D; Uskoković-Marković, S; Ranković, D; Milenković, M; Jevremović, A; Vasiljević, Nedić B; Milojević-Rakić, M; Bajuk-Bogdanović, D Double active BEA zeolite/silver tungstophosphates – Antimicrobial effects and pesticide removal Journal Article Science of the Total Environment, 735 , 2020. @article{Janićijević2020, title = {Double active BEA zeolite/silver tungstophosphates – Antimicrobial effects and pesticide removal}, author = {D Janićijević and S Uskoković-Marković and D Ranković and M Milenković and A Jevremović and B Nedić Vasiljević and M Milojević-Rakić and D Bajuk-Bogdanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085236820&doi=10.1016%2fj.scitotenv.2020.139530&partnerID=40&md5=8e428aeddbb498a0dca4e994762a6904}, doi = {10.1016/j.scitotenv.2020.139530}, year = {2020}, date = {2020-01-01}, journal = {Science of the Total Environment}, volume = {735}, abstract = {Novel composites of BEA zeolite and silver tungstophosphate were prepared by different procedures: two-step impregnation, ion-exchange, and as physical mixtures with varying component mass ratios. Composites were characterized using Atomic force microscopy, Infrared, Raman and Atomic absorption spectroscopy, and results were related to adsorption properties and antimicrobial efficiencies of the composites. Prepared samples were tested as antimicrobial agents for fungal and different bacterial strains, as well as for adsorbents for pesticide nicosulfuron in aqueous solutions by using High-performance liquid chromatography. Experimental conditions for batch adsorption testing were optimized in order to efficiently eliminate nicosulfuron from aqueous solutions, while enabling antimicrobial activity of these advanced materials. Antimicrobial efficiency of composites was verified, and indicated that silver ion persistence in the solid phase is of utmost significance for the antimicrobial activity. Spectroscopic investigation revealed interaction of the silver tungstophosphate active phase and the zeolite framework, giving evidence of uniform distribution of active sites in the synthesized materials that proved to be essential for adsorption application. The best obtained adsorption capacity, as well as highest antimicrobial efficiency, is found for composite samples prepared by two-step impregnation with (BEA: silver tungstophosphate) mass ratio 2:1. The amount of nicosulfuron removed from water suspension was 38.2 mg per gram of composite, and the minimum inhibitory concentration determined for all investigated gram-negative bacteria was 125 μg mL−1. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Novel composites of BEA zeolite and silver tungstophosphate were prepared by different procedures: two-step impregnation, ion-exchange, and as physical mixtures with varying component mass ratios. Composites were characterized using Atomic force microscopy, Infrared, Raman and Atomic absorption spectroscopy, and results were related to adsorption properties and antimicrobial efficiencies of the composites. Prepared samples were tested as antimicrobial agents for fungal and different bacterial strains, as well as for adsorbents for pesticide nicosulfuron in aqueous solutions by using High-performance liquid chromatography. Experimental conditions for batch adsorption testing were optimized in order to efficiently eliminate nicosulfuron from aqueous solutions, while enabling antimicrobial activity of these advanced materials. Antimicrobial efficiency of composites was verified, and indicated that silver ion persistence in the solid phase is of utmost significance for the antimicrobial activity. Spectroscopic investigation revealed interaction of the silver tungstophosphate active phase and the zeolite framework, giving evidence of uniform distribution of active sites in the synthesized materials that proved to be essential for adsorption application. The best obtained adsorption capacity, as well as highest antimicrobial efficiency, is found for composite samples prepared by two-step impregnation with (BEA: silver tungstophosphate) mass ratio 2:1. The amount of nicosulfuron removed from water suspension was 38.2 mg per gram of composite, and the minimum inhibitory concentration determined for all investigated gram-negative bacteria was 125 μg mL−1. © 2020 Elsevier B.V. |
Mitić, M; Milovanović, M; Veljković, F; Perić-Grujić, A; Veličković, S; Jerosimić, S Theoretical and experimental study of small potassium-bromide KnBr(0,1+) (n = 2–6) and KnBrn-1(0,1+) (n = 3–5) clusters Journal Article Journal of Alloys and Compounds, 835 , 2020. @article{Mitić2020, title = {Theoretical and experimental study of small potassium-bromide KnBr(0,1+) (n = 2–6) and KnBrn-1(0,1+) (n = 3–5) clusters}, author = {M Mitić and M Milovanović and F Veljković and A Perić-Grujić and S Veličković and S Jerosimić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084049008&doi=10.1016%2fj.jallcom.2020.155301&partnerID=40&md5=654ac78bc3913ac2d7a52306ac4bab64}, doi = {10.1016/j.jallcom.2020.155301}, year = {2020}, date = {2020-01-01}, journal = {Journal of Alloys and Compounds}, volume = {835}, abstract = {In the present paper, the results of combined theoretical and experimental investigation of small non-stoichiometric bromine-doped potassium clusters are reported. Potassium-bromide clusters were obtained by the Knudsen cell combined with surface ionization in the temperature range of 1000–1600 K, and selected by a magnetic sector mass spectrometer. Positive ions of KnBr (n = 3–6) and KnBrn-1 (n = 3–5) clusters were detected for the first time in one set measurement. In order to reveal the geometrical structure of each type of detected cluster, the randomized search algorithm was employed to survey the (Born-Oppenheimer) potential energy surface of both the neutral and cationic KnBr(0,1+) (n = 1–6) and KnBrn-1(0,1+) (n=3–5) clusters, followed by Density functional theory geometry optimizations, and many lowest-energy conformational isomers are presented. From the total electronic energies of clusters computed by the ab initio RCCSD(T)/ECP10MDF(K),cc-pVTZ-PP(Br) method at obtained equilibrium nuclear geometries, the following stability parameters of clusters were computed: their relative energies, the adiabatic and vertical ionization energies, binding energies per atom, and dissociation energies. Both experimental and theoretical results have shown that the title clusters belong to the group of “superalkali” clusters. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the present paper, the results of combined theoretical and experimental investigation of small non-stoichiometric bromine-doped potassium clusters are reported. Potassium-bromide clusters were obtained by the Knudsen cell combined with surface ionization in the temperature range of 1000–1600 K, and selected by a magnetic sector mass spectrometer. Positive ions of KnBr (n = 3–6) and KnBrn-1 (n = 3–5) clusters were detected for the first time in one set measurement. In order to reveal the geometrical structure of each type of detected cluster, the randomized search algorithm was employed to survey the (Born-Oppenheimer) potential energy surface of both the neutral and cationic KnBr(0,1+) (n = 1–6) and KnBrn-1(0,1+) (n=3–5) clusters, followed by Density functional theory geometry optimizations, and many lowest-energy conformational isomers are presented. From the total electronic energies of clusters computed by the ab initio RCCSD(T)/ECP10MDF(K),cc-pVTZ-PP(Br) method at obtained equilibrium nuclear geometries, the following stability parameters of clusters were computed: their relative energies, the adiabatic and vertical ionization energies, binding energies per atom, and dissociation energies. Both experimental and theoretical results have shown that the title clusters belong to the group of “superalkali” clusters. © 2020 Elsevier B.V. |
Novčić, K A; Dobrota, A S; Petković, M; Johansson, B; Skorodumova, N V; Mentus, S V; Pašti, I A Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries – the impact of the computational scheme Journal Article Electrochimica Acta, 354 , 2020. @article{Novčić2020, title = {Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries – the impact of the computational scheme}, author = {K A Novčić and A S Dobrota and M Petković and B Johansson and N V Skorodumova and S V Mentus and I A Pašti}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087973660&doi=10.1016%2fj.electacta.2020.136735&partnerID=40&md5=3e5bdf0fec3b50f407572ac15428741c}, doi = {10.1016/j.electacta.2020.136735}, year = {2020}, date = {2020-01-01}, journal = {Electrochimica Acta}, volume = {354}, abstract = {Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates. © 2020 |
Milenković, D A; Dimić, D S; Avdović, E H; Amić, A D; Marković, Dimitrić J M; Marković, Z S Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products Journal Article Chemical Engineering Journal, 395 , 2020. @article{Milenković2020, title = {Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products}, author = {D A Milenković and D S Dimić and E H Avdović and A D Amić and J M Dimitrić Marković and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083333113&doi=10.1016%2fj.cej.2020.124971&partnerID=40&md5=66e7cb80160ef8312eccd626299c8eb9}, doi = {10.1016/j.cej.2020.124971}, year = {2020}, date = {2020-01-01}, journal = {Chemical Engineering Journal}, volume = {395}, abstract = {The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020 |
Mladenović, D; Vujković, M; Mentus, S; Santos, D M F; Rocha, R P; Sequeira, C A C; Figueiredo, J L; Šljukić, B Carbon-supported mo2c for oxygen reduction reaction electrocatalysis Journal Article Nanomaterials, 10 (9), pp. 1-12, 2020. @article{Mladenović20201, title = {Carbon-supported mo2c for oxygen reduction reaction electrocatalysis}, author = {D Mladenović and M Vujković and S Mentus and D M F Santos and R P Rocha and C A C Sequeira and J L Figueiredo and B Šljukić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090765590&doi=10.3390%2fnano10091805&partnerID=40&md5=a2dee5f292f3a717d6663dc3ccbbaabc}, doi = {10.3390/nano10091805}, year = {2020}, date = {2020-01-01}, journal = {Nanomaterials}, volume = {10}, number = {9}, pages = {1-12}, abstract = {Molybdenum carbide (Mo2C)-based electrocatalysts were prepared using two different carbon supports, commercial carbon nanotubes (CNTs) and synthesised carbon xerogel (CXG), to be studied from the point of view of both capacitive and electrocatalytic properties. Cation type (K+ or Na+) in the alkaline electrolyte solution did not affect the rate of formation of the electrical double layer at a low scan rate of 10 mV s−1 . Conversely, the different mobility of these cations through the electrolyte was found to be crucial for the rate of double-layer formation at higher scan rates. Molybdenum carbide supported on carbon xerogel (Mo2C/CXG) showed ca. 3 times higher double-layer capacity amounting to 75 mF cm−2 compared to molybdenum carbide supported on carbon nanotubes (Mo2C/CNT) with a value of 23 mF cm−2 due to having more than double the surface area size. The electrocatalytic properties of carbon-supported molybdenum carbides for the oxygen reduction reaction in alkaline media were evaluated using linear scan voltammetry with a rotating disk electrode. The studied materials demonstrated good electrocatalytic performance with Mo2C/CXG delivering higher current densities at more positive onset and half-wave potential. The number of electrons exchanged during oxygen reduction reaction (ORR) was calculated to be 3, suggesting a combination of four-and two-electron mechanism. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molybdenum carbide (Mo2C)-based electrocatalysts were prepared using two different carbon supports, commercial carbon nanotubes (CNTs) and synthesised carbon xerogel (CXG), to be studied from the point of view of both capacitive and electrocatalytic properties. Cation type (K+ or Na+) in the alkaline electrolyte solution did not affect the rate of formation of the electrical double layer at a low scan rate of 10 mV s−1 . Conversely, the different mobility of these cations through the electrolyte was found to be crucial for the rate of double-layer formation at higher scan rates. Molybdenum carbide supported on carbon xerogel (Mo2C/CXG) showed ca. 3 times higher double-layer capacity amounting to 75 mF cm−2 compared to molybdenum carbide supported on carbon nanotubes (Mo2C/CNT) with a value of 23 mF cm−2 due to having more than double the surface area size. The electrocatalytic properties of carbon-supported molybdenum carbides for the oxygen reduction reaction in alkaline media were evaluated using linear scan voltammetry with a rotating disk electrode. The studied materials demonstrated good electrocatalytic performance with Mo2C/CXG delivering higher current densities at more positive onset and half-wave potential. The number of electrons exchanged during oxygen reduction reaction (ORR) was calculated to be 3, suggesting a combination of four-and two-electron mechanism. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. |
Jerosimić, S; Milovanović, M; Koprivica, D; Wester, R; Gianturco, F A Structural properties of possible interstellar valence anions of the series HC: NN-(n = 3, 5, 7, 9) Journal Article Physical Chemistry Chemical Physics, 22 (30), pp. 17263-17274, 2020. @article{Jerosimić202017263, title = {Structural properties of possible interstellar valence anions of the series HC: NN-(n = 3, 5, 7, 9)}, author = {S Jerosimić and M Milovanović and D Koprivica and R Wester and F A Gianturco}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089205494&doi=10.1039%2fd0cp02666b&partnerID=40&md5=e37b048b5f0762a84e6b871b1cf219d5}, doi = {10.1039/d0cp02666b}, year = {2020}, date = {2020-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, number = {30}, pages = {17263-17274}, abstract = {In this contribution we investigate the structural properties of stable anions of small carbon clusters, with one nitrogen and one hydrogen atoms attached to the C-cluster, to surmise their possible existence in the Interstellar Medium (ISM). Many possible configurational (geometrical) isomers with positive vertical electron detachment values are presented, and arranged according to their relative energy. Specific attention is paid to the structures of the lowest-energy valence isomers, the chain-structures of HC7N- and HC9N- anions with quasilinear and linear geometry, respectively. They exhibit relatively large permanent dipole moments (2.697 and 5.034 Debye) and adiabatic electron affinities (AEAs) of 1.13 and 1.35 eV. Isomers of the HNCn- family and many branched structures are possible stable species viable for detection in the ISM. © 2020 the Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this contribution we investigate the structural properties of stable anions of small carbon clusters, with one nitrogen and one hydrogen atoms attached to the C-cluster, to surmise their possible existence in the Interstellar Medium (ISM). Many possible configurational (geometrical) isomers with positive vertical electron detachment values are presented, and arranged according to their relative energy. Specific attention is paid to the structures of the lowest-energy valence isomers, the chain-structures of HC7N- and HC9N- anions with quasilinear and linear geometry, respectively. They exhibit relatively large permanent dipole moments (2.697 and 5.034 Debye) and adiabatic electron affinities (AEAs) of 1.13 and 1.35 eV. Isomers of the HNCn- family and many branched structures are possible stable species viable for detection in the ISM. © 2020 the Owner Societies. |
Jovanović, T; Milikić, J; Cvjetićanin, N; Stojadinović, S; Šljukić, B Performance of Au/Ti and Au/TiO2 Nanotube Array Electrodes for Borohydride Oxidation and Oxygen Reduction Reaction in Alkaline Media Journal Article Electroanalysis, 32 (8), pp. 1867-1874, 2020. @article{Jovanović20201867, title = {Performance of Au/Ti and Au/TiO2 Nanotube Array Electrodes for Borohydride Oxidation and Oxygen Reduction Reaction in Alkaline Media}, author = {T Jovanović and J Milikić and N Cvjetićanin and S Stojadinović and B Šljukić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085329940&doi=10.1002%2felan.202060015&partnerID=40&md5=599e7a8859744c007b150dc86f45ced7}, doi = {10.1002/elan.202060015}, year = {2020}, date = {2020-01-01}, journal = {Electroanalysis}, volume = {32}, number = {8}, pages = {1867-1874}, abstract = {Polarization curves and complex kinetics of oxygen reduction (ORR) and borohydride oxidation (BOR) reaction were evaluated at thin Au layer on Ti and TiO2 electrodes. TiO2 electrodes prepared included amorphous TiO2 (AM−TiO2) and anatase (A−TiO2). The electrodes structure and nanotube arrays morphology were observed by XRD and SEM, respectively. All electrodes show activity for both ORR and BOR. The use of Au layer over A−TiO2 produces the strongest synergistic effect for ORR with exchange of 3 electrons. On the other hand, the strongest effect for BOR was observed in case of Au/Ti. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polarization curves and complex kinetics of oxygen reduction (ORR) and borohydride oxidation (BOR) reaction were evaluated at thin Au layer on Ti and TiO2 electrodes. TiO2 electrodes prepared included amorphous TiO2 (AM−TiO2) and anatase (A−TiO2). The electrodes structure and nanotube arrays morphology were observed by XRD and SEM, respectively. All electrodes show activity for both ORR and BOR. The use of Au layer over A−TiO2 produces the strongest synergistic effect for ORR with exchange of 3 electrons. On the other hand, the strongest effect for BOR was observed in case of Au/Ti. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Maksimović, J; Čupić, Ž; Manojlović, N; Đerić, A; Anić, S; Kolar-Anić, L Bray–Liebhafsky oscillatory reaction as the matrix system for the kinetic determination of microquantities of alizarin and purpurin Journal Article Reaction Kinetics, Mechanisms and Catalysis, 130 (2), pp. 655-668, 2020. @article{Maksimović2020655, title = {Bray–Liebhafsky oscillatory reaction as the matrix system for the kinetic determination of microquantities of alizarin and purpurin}, author = {J Maksimović and Ž Čupić and N Manojlović and A Đerić and S Anić and L Kolar-Anić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086167239&doi=10.1007%2fs11144-020-01798-5&partnerID=40&md5=5352cc7dd1f1ca3b7fb3fae8acfe957d}, doi = {10.1007/s11144-020-01798-5}, year = {2020}, date = {2020-01-01}, journal = {Reaction Kinetics, Mechanisms and Catalysis}, volume = {130}, number = {2}, pages = {655-668}, abstract = {Two hydroxyanthraquinones, alizarin and purpurin, that have been used throughout history as a natural pigment, were extracted from roots of Rubia tinctorum from Serbia. As substances with important chemical activities and, therefore, with wide applications (for example in dyeing textile fabrics as well as in pharmacy because of their anti-inflammatory, anti-cancer, antiviral, antimicrobial and antioxidant activities, etc.) they were analyzed in the kinetically very sensitive Bray–Liebhafsky (BL) oscillatory reaction. However, although they are both, hydroxyanthraquinones it is shown that their interactions with BL nonlinear reaction system differ significantly. Consequently, two different reactions were used to explain the mechanism of their chemical activities. The numerical simulations based on a standard model of the BL oscillatory reaction together with proposed reactions due to alizarin/purpurin interactions with a matrix are correlated with experimental investigations. Moreover, it is shown that very small amounts of alizarin and purpurin (from about 1 × 10–7 M) produce the response of the BL matrix such that micro-quantitative analysis based on the BL oscillatory reaction can be successfully performed in this reaction system. The linear response of the BL matrix on the presence of alizarin and purpurin (necessary for microquantitative determination) is analyzed as a function of two concentration sensitive parameters: pre-oscillatory period τ1 and potential shift after perturbation ΔE. © 2020, Akadémiai Kiadó, Budapest, Hungary.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two hydroxyanthraquinones, alizarin and purpurin, that have been used throughout history as a natural pigment, were extracted from roots of Rubia tinctorum from Serbia. As substances with important chemical activities and, therefore, with wide applications (for example in dyeing textile fabrics as well as in pharmacy because of their anti-inflammatory, anti-cancer, antiviral, antimicrobial and antioxidant activities, etc.) they were analyzed in the kinetically very sensitive Bray–Liebhafsky (BL) oscillatory reaction. However, although they are both, hydroxyanthraquinones it is shown that their interactions with BL nonlinear reaction system differ significantly. Consequently, two different reactions were used to explain the mechanism of their chemical activities. The numerical simulations based on a standard model of the BL oscillatory reaction together with proposed reactions due to alizarin/purpurin interactions with a matrix are correlated with experimental investigations. Moreover, it is shown that very small amounts of alizarin and purpurin (from about 1 × 10–7 M) produce the response of the BL matrix such that micro-quantitative analysis based on the BL oscillatory reaction can be successfully performed in this reaction system. The linear response of the BL matrix on the presence of alizarin and purpurin (necessary for microquantitative determination) is analyzed as a function of two concentration sensitive parameters: pre-oscillatory period τ1 and potential shift after perturbation ΔE. © 2020, Akadémiai Kiadó, Budapest, Hungary. |
Pagnacco, M; Maksimović, J; Mudrinić, T; Banković, P; Nedić-Vasiljević, B; Milutinović-Nikolić, A ChemistrySelect, 5 (27), pp. 8137-8141, 2020. @article{Pagnacco20208137, title = {Oscillatory Briggs-Rauscher Reaction as “Fingerprint” for Bentonite Identification: The Fine-Tuning of Oscillatory Dynamics with Addition of Clay}, author = {M Pagnacco and J Maksimović and T Mudrinić and P Banković and B Nedić-Vasiljević and A Milutinović-Nikolić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088381217&doi=10.1002%2fslct.202000874&partnerID=40&md5=afe6489149bdbf3d328cd3044fbbe656}, doi = {10.1002/slct.202000874}, year = {2020}, date = {2020-01-01}, journal = {ChemistrySelect}, volume = {5}, number = {27}, pages = {8137-8141}, abstract = {The oscillatory Briggs-Rauscher (BR) reaction was applied on solid insoluble materials i. e. bentonite clays. Under the same BR experimental conditions, the addition of identical masses of bentonite of different origin resulted in different effects on oscillatory time duration (τ): no influence, quenching, or prolongation. It was found that the following bentonite properties: montmorillonite/beidellite ratio; cation exchange capacity; principal exchange cation; extent of iron leaching in acidic environment of BR reaction; and specific surface area of clay were not exclusively responsible for observed behavior. On the other hand, the influence of added mass, for all investigated clays, resulted in the same behavior pattern. The increase of the mass of added clay increased τ up to the certain maximal value (τmax, mmax) characteristic for each clay. Further increase of mass resulted in quenching. Therefore, (τmax, mmax) pair can be regarded as the “fingerprint” characteristic of bentonite useful for identification of its origin. Furthermore, the addition of naturally occurring and non-toxic clay in an oscillatory reaction can offer a versatile approach to tune the oscillation dynamics of nonlinear chemical systems. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } The oscillatory Briggs-Rauscher (BR) reaction was applied on solid insoluble materials i. e. bentonite clays. Under the same BR experimental conditions, the addition of identical masses of bentonite of different origin resulted in different effects on oscillatory time duration (τ): no influence, quenching, or prolongation. It was found that the following bentonite properties: montmorillonite/beidellite ratio; cation exchange capacity; principal exchange cation; extent of iron leaching in acidic environment of BR reaction; and specific surface area of clay were not exclusively responsible for observed behavior. On the other hand, the influence of added mass, for all investigated clays, resulted in the same behavior pattern. The increase of the mass of added clay increased τ up to the certain maximal value (τmax, mmax) characteristic for each clay. Further increase of mass resulted in quenching. Therefore, (τmax, mmax) pair can be regarded as the “fingerprint” characteristic of bentonite useful for identification of its origin. Furthermore, the addition of naturally occurring and non-toxic clay in an oscillatory reaction can offer a versatile approach to tune the oscillation dynamics of nonlinear chemical systems. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Nakarada, Đ; Pejin, B; Tommonaro, G; Mojović, M Journal of Liposome Research, 30 (3), pp. 218-226, 2020. @article{Nakarada2020218, title = {Liposomal integration method for assessing antioxidative activity of water insoluble compounds towards biologically relevant free radicals: example of avarol}, author = {Đ Nakarada and B Pejin and G Tommonaro and M Mojović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85067698469&doi=10.1080%2f08982104.2019.1625378&partnerID=40&md5=99e8b9d2e73b4f03bac1888b0acd0d59}, doi = {10.1080/08982104.2019.1625378}, year = {2020}, date = {2020-01-01}, journal = {Journal of Liposome Research}, volume = {30}, number = {3}, pages = {218-226}, abstract = {The liposomal integration method, in conjunction with electron paramagnetic resonance (EPR) spectroscopy, has been presented for the investigation of antioxidant activity of selected water-insoluble compound towards biologically relevant free radicals. This method was applied to avarol, a sesquiterpenoid hydroquinone isolated from the marine sponge Dysidea avara. The antioxidant activity of water-insoluble avarol towards •OH, O2•− and NO• radicals was attained by its incorporation into the DPPC liposomes bilayer, and towards ascorbyl radicals in the organic solvent. Avarol’s activity towards •OH, O2•−, NO• and ascorbyl radicals was 86.2%, 50.9%, 23.6% and 61.8%, respectively, showing its significant radical scavenging potential. © 2019 Informa UK Limited, trading as Taylor & Francis Group.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The liposomal integration method, in conjunction with electron paramagnetic resonance (EPR) spectroscopy, has been presented for the investigation of antioxidant activity of selected water-insoluble compound towards biologically relevant free radicals. This method was applied to avarol, a sesquiterpenoid hydroquinone isolated from the marine sponge Dysidea avara. The antioxidant activity of water-insoluble avarol towards •OH, O2•− and NO• radicals was attained by its incorporation into the DPPC liposomes bilayer, and towards ascorbyl radicals in the organic solvent. Avarol’s activity towards •OH, O2•−, NO• and ascorbyl radicals was 86.2%, 50.9%, 23.6% and 61.8%, respectively, showing its significant radical scavenging potential. © 2019 Informa UK Limited, trading as Taylor & Francis Group. |
Milovanović, M Z; Mitić, M L Ab initio investigation of dicyanoacetylene cation in the ground electronic state: Vibronic coupling and photoionization selection rules Journal Article Journal of Molecular Spectroscopy, 372 , 2020. @article{Milovanović2020, title = {Ab initio investigation of dicyanoacetylene cation in the ground electronic state: Vibronic coupling and photoionization selection rules}, author = {M Z Milovanović and M L Mitić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088496587&doi=10.1016%2fj.jms.2020.111330&partnerID=40&md5=b8b98e78caa39c93a7ce708764343a02}, doi = {10.1016/j.jms.2020.111330}, year = {2020}, date = {2020-01-01}, journal = {Journal of Molecular Spectroscopy}, volume = {372}, abstract = {Dicyanoacetylene cation, C4N2+, is a species of astrochemical interest. The vibronic spectrum of the ground electronic state of the C4N2+ (X2Πu) is affected by a combination of the Renner–Teller and spin-orbit coupling. The first theoretical prediction of the vibronic energy levels in the ground electronic state of C4N2+ was carried out in 2011 (Ranković et al., 2011). Recently, Lamarre et al. (2015) reported the vibronic spectrum of this species obtained by the PFI-ZEKE photoelectron spectroscopy. They reported discrepancies between the experimental results and the previous theoretical predictions. In the present work, those discrepancies were resolved by using Renner-Teller parameters obtained by the explicitly correlated coupled-cluster method, CCSD(T)-F12, which includes dynamical correlation to a sufficient extent. Using these parameters, the vibronic spectrum was calculated in a variational manner. Reassignment of two experimentally observed vibronic levels is proposed and agreement between the calculated and experimentally observed levels was achieved. Furthermore, the photoionization selection rules were applied to the X+2Πu←X1Σg+ transition with the aim to elucidate more details about this process. © 2020 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dicyanoacetylene cation, C4N2+, is a species of astrochemical interest. The vibronic spectrum of the ground electronic state of the C4N2+ (X2Πu) is affected by a combination of the Renner–Teller and spin-orbit coupling. The first theoretical prediction of the vibronic energy levels in the ground electronic state of C4N2+ was carried out in 2011 (Ranković et al., 2011). Recently, Lamarre et al. (2015) reported the vibronic spectrum of this species obtained by the PFI-ZEKE photoelectron spectroscopy. They reported discrepancies between the experimental results and the previous theoretical predictions. In the present work, those discrepancies were resolved by using Renner-Teller parameters obtained by the explicitly correlated coupled-cluster method, CCSD(T)-F12, which includes dynamical correlation to a sufficient extent. Using these parameters, the vibronic spectrum was calculated in a variational manner. Reassignment of two experimentally observed vibronic levels is proposed and agreement between the calculated and experimentally observed levels was achieved. Furthermore, the photoionization selection rules were applied to the X+2Πu←X1Σg+ transition with the aim to elucidate more details about this process. © 2020 Elsevier Inc. |
Matijević, M; Nakarada, Đ; Liang, X; Korićanac, L; Rajsiglova, L; Vannucci, L; Nešić, M; Vranješ, M; Mojović, M; Mi, L; Estrela-Lopis, I; Böttner, J; Šaponjić, Z; Petković, M; Stepić, M Biocompatibility of TiO2 prolate nanospheroids as a potential photosenzitizer in therapy of cancer Journal Article Journal of Nanoparticle Research, 22 (7), 2020. @article{Matijević2020, title = {Biocompatibility of TiO2 prolate nanospheroids as a potential photosenzitizer in therapy of cancer}, author = {M Matijević and Đ Nakarada and X Liang and L Korićanac and L Rajsiglova and L Vannucci and M Nešić and M Vranješ and M Mojović and L Mi and I Estrela-Lopis and J Böttner and Z Šaponjić and M Petković and M Stepić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087054250&doi=10.1007%2fs11051-020-04899-3&partnerID=40&md5=9019709ed3fedee914b332555d4534ce}, doi = {10.1007/s11051-020-04899-3}, year = {2020}, date = {2020-01-01}, journal = {Journal of Nanoparticle Research}, volume = {22}, number = {7}, abstract = {TiO2 prolatenanospheroids (PNSs) may be photosensitizers (PSs), which act by catalyzation of hydroxyl radical (∙OH) formation upon light illumination. ∙OH might, in turn, contribute to killing of cancer cells. On the other hand, there is great concern about toxicity in the dark of TiO2 nanoparticles in general. In this work, we have investigated the biocompatibility of TiO2 PNSs of the anatase crystal form (length between 100 and 300 nm and width 50 nm) in the dark with immune cells and light-induced cytotoxicity on several cancer cell lines. The effects of the treatment of different cell lines with several concentrations of TiO2 PNSs suspensions showed the specifics of cells’ viability and the intracellular localization. The results of in vitro studies obtained by cytotoxicity assays adjusted to individual cell lines’ metabolism point towards the biocompatibility of TiO2 PNSs at low and moderate concentrations in the dark, which neither kill the cells, nor induce activation of the immune system cells. Laser scanning confocal microscopy revealed that PNSs are taken up by cells, and insight into the intracellular distribution was obtained in this study. © 2020, Springer Nature B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } TiO2 prolatenanospheroids (PNSs) may be photosensitizers (PSs), which act by catalyzation of hydroxyl radical (∙OH) formation upon light illumination. ∙OH might, in turn, contribute to killing of cancer cells. On the other hand, there is great concern about toxicity in the dark of TiO2 nanoparticles in general. In this work, we have investigated the biocompatibility of TiO2 PNSs of the anatase crystal form (length between 100 and 300 nm and width 50 nm) in the dark with immune cells and light-induced cytotoxicity on several cancer cell lines. The effects of the treatment of different cell lines with several concentrations of TiO2 PNSs suspensions showed the specifics of cells’ viability and the intracellular localization. The results of in vitro studies obtained by cytotoxicity assays adjusted to individual cell lines’ metabolism point towards the biocompatibility of TiO2 PNSs at low and moderate concentrations in the dark, which neither kill the cells, nor induce activation of the immune system cells. Laser scanning confocal microscopy revealed that PNSs are taken up by cells, and insight into the intracellular distribution was obtained in this study. © 2020, Springer Nature B.V. |
Milenković, D; Avdović, E; Dimić, D; Sudha, S; Ramarajan, D; Milanović, ; Trifunović, S; Marković, Z S Journal of Molecular Structure, 1209 , 2020. @article{Milenković2020b, title = {Vibrational and Hirshfeld surface analyses, quantum chemical calculations, and molecular docking studies of coumarin derivative 3-(1-m-toluidinoethylidene)-chromane-2,4-dione and its corresponding palladium(II) complex}, author = {D Milenković and E Avdović and D Dimić and S Sudha and D Ramarajan and Milanović and S Trifunović and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080037349&doi=10.1016%2fj.molstruc.2020.127935&partnerID=40&md5=b6333b566889ba33eb9c616fd994d2cc}, doi = {10.1016/j.molstruc.2020.127935}, year = {2020}, date = {2020-01-01}, journal = {Journal of Molecular Structure}, volume = {1209}, abstract = {In this study, the analysis of vibrational spectra and electronic structure of 3-(1-m-toluidinoethylidene)-chromane-2,4-dione (L1) and its corresponding palladium (II) complex (C1) was employed to characterize the spectroscopic behavior and molecular structure of the investigated compounds by applying B3LYP-D3BJ/6-311+G(d,p) level of theory. Hirshfeld surface analysis of the intermolecular interactions in crystal structure L1 was performed. The AIM and NBO analyses were used to understand the type, nature, and strength of intramolecular interactions and to examine the electronic structure of the studied molecules. The calculation of HOMO and LUMO energies was applied in order to present the charge transfer within the molecule. The computational molecular docking studies of title compounds was performed with special emphasis on differences in binding of ligand and complex. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this study, the analysis of vibrational spectra and electronic structure of 3-(1-m-toluidinoethylidene)-chromane-2,4-dione (L1) and its corresponding palladium (II) complex (C1) was employed to characterize the spectroscopic behavior and molecular structure of the investigated compounds by applying B3LYP-D3BJ/6-311+G(d,p) level of theory. Hirshfeld surface analysis of the intermolecular interactions in crystal structure L1 was performed. The AIM and NBO analyses were used to understand the type, nature, and strength of intramolecular interactions and to examine the electronic structure of the studied molecules. The calculation of HOMO and LUMO energies was applied in order to present the charge transfer within the molecule. The computational molecular docking studies of title compounds was performed with special emphasis on differences in binding of ligand and complex. © 2020 |
Ilić, Medić M; Bundaleski, N; Ivanović, N; Teodoro, O M N D; Rakočević, Z; Minić, D; Romčević, N; Radisavljević, I XPS measurements of air-exposed Cd(Zn)1–xFexTe1–ySey surfaces revisited Journal Article Vacuum, 176 , 2020. @article{MedićIlić2020, title = {XPS measurements of air-exposed Cd(Zn)1–xFexTe1–ySey surfaces revisited}, author = {M Medić Ilić and N Bundaleski and N Ivanović and O M N D Teodoro and Z Rakočević and D Minić and N Romčević and I Radisavljević}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082390920&doi=10.1016%2fj.vacuum.2020.109340&partnerID=40&md5=61cbfffe3734322d74f90fc164992f5f}, doi = {10.1016/j.vacuum.2020.109340}, year = {2020}, date = {2020-01-01}, journal = {Vacuum}, volume = {176}, abstract = {Recently introduced model for quantitative analysis of in-depth non-uniform surfaces is applied to reexamine the X-ray Photoelectron Spectroscopy (XPS) data of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 crystalline samples. Special attention is paid to the precise identification of phases which form the bulk-like near-surface region and the surface overlayers (the oxide layer and the layer of organic impurities), as well as the influence of surface morphology on the measurements. The obtained results fully support earlier qualitative estimations, but also provide new quantitative insight into the composition of the three investigated regions. The near-surface region of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 samples is slightly electropositive, with cation/anion ratio 52:48 and 53:47, respectively. Model surface structures, which are fully compatible with the experimental results, comprise 0.76 nm thick CdTeO3 layer at the surface of Cd0.99Fe0.01Te0.97Se0.03 and 0.33 nm thick mixed ZnO/TeO2 oxide layer on Zn0.98Fe0.02Te0.91Se0.09. In both samples the oxide layer is only a few atomic layers thick, implying that it suppresses further rapid migration of oxygen into the bulk. © 2020 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recently introduced model for quantitative analysis of in-depth non-uniform surfaces is applied to reexamine the X-ray Photoelectron Spectroscopy (XPS) data of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 crystalline samples. Special attention is paid to the precise identification of phases which form the bulk-like near-surface region and the surface overlayers (the oxide layer and the layer of organic impurities), as well as the influence of surface morphology on the measurements. The obtained results fully support earlier qualitative estimations, but also provide new quantitative insight into the composition of the three investigated regions. The near-surface region of Cd0.99Fe0.01Te0.97Se0.03 and Zn0.98Fe0.02Te0.91Se0.09 samples is slightly electropositive, with cation/anion ratio 52:48 and 53:47, respectively. Model surface structures, which are fully compatible with the experimental results, comprise 0.76 nm thick CdTeO3 layer at the surface of Cd0.99Fe0.01Te0.97Se0.03 and 0.33 nm thick mixed ZnO/TeO2 oxide layer on Zn0.98Fe0.02Te0.91Se0.09. In both samples the oxide layer is only a few atomic layers thick, implying that it suppresses further rapid migration of oxygen into the bulk. © 2020 Elsevier Ltd |
Ranđelović, D; Jakovljević, K; Mišljenović, T; Savović, J; Kuzmanović, M; Mihailović, N; Jovanović, S Accumulation of Potentially Toxic Elements in Invasive Ambrosia artemisiifolia on Sites with Different Levels of Anthropogenic Pollution Journal Article Water, Air, and Soil Pollution, 231 (6), 2020. @article{Ranđelović2020, title = {Accumulation of Potentially Toxic Elements in Invasive Ambrosia artemisiifolia on Sites with Different Levels of Anthropogenic Pollution}, author = {D Ranđelović and K Jakovljević and T Mišljenović and J Savović and M Kuzmanović and N Mihailović and S Jovanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085531031&doi=10.1007%2fs11270-020-04655-2&partnerID=40&md5=0ed44990944f02acefd1ae79b2220ffa}, doi = {10.1007/s11270-020-04655-2}, year = {2020}, date = {2020-01-01}, journal = {Water, Air, and Soil Pollution}, volume = {231}, number = {6}, abstract = {This study investigated invasive Ambrosia artemisiifolia from five localities with different levels of anthropogenic pollution in order to determine the potential for accumulation of trace metals and metaloids. Physical characteristics of the soil are presented, together with concentrations of As, B, Ba, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sr, and Zn in both plant and soil. The tested samples displayed considerable differences in element concentrations, depending on the level of anthropogenic activities, with the highest concentrations of elements observed in samples from Stolice and Piskanja, the sites with most intensive human influence. A trend of shoot accumulation can be observed in A. artemisiifolia, but without hyperaccumulation, along with lower root concentrations in almost all analyzed samples. This may pose an additional environmental risk, as accumulated elements can spread to other components of the ecosystem. While A. artemisiifolia acumulates a high and even toxic rate of B in shoots regardless of boron concentration in soil, there is a high correlation of Ba, Pb, and Zn concentrations in species shoots with their respective concentration in the soil. Successful colonization of both natural and anthropogenically polluted habitats indicates high tolerance of A. artemisiifolia, which complements its wide environmental amplitude. © 2020, Springer Nature Switzerland AG.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study investigated invasive Ambrosia artemisiifolia from five localities with different levels of anthropogenic pollution in order to determine the potential for accumulation of trace metals and metaloids. Physical characteristics of the soil are presented, together with concentrations of As, B, Ba, Ca, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sr, and Zn in both plant and soil. The tested samples displayed considerable differences in element concentrations, depending on the level of anthropogenic activities, with the highest concentrations of elements observed in samples from Stolice and Piskanja, the sites with most intensive human influence. A trend of shoot accumulation can be observed in A. artemisiifolia, but without hyperaccumulation, along with lower root concentrations in almost all analyzed samples. This may pose an additional environmental risk, as accumulated elements can spread to other components of the ecosystem. While A. artemisiifolia acumulates a high and even toxic rate of B in shoots regardless of boron concentration in soil, there is a high correlation of Ba, Pb, and Zn concentrations in species shoots with their respective concentration in the soil. Successful colonization of both natural and anthropogenically polluted habitats indicates high tolerance of A. artemisiifolia, which complements its wide environmental amplitude. © 2020, Springer Nature Switzerland AG. |
Dobrota, A S; Pašti, I A; Mentus, S V; Johansson, B; Skorodumova, N V Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects Journal Article Applied Surface Science, 514 , 2020. @article{Dobrota2020, title = {Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects}, author = {A S Dobrota and I A Pašti and S V Mentus and B Johansson and N V Skorodumova}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081026675&doi=10.1016%2fj.apsusc.2020.145937&partnerID=40&md5=144a6d323679a1f70b41dac3fc54ad91}, doi = {10.1016/j.apsusc.2020.145937}, year = {2020}, date = {2020-01-01}, journal = {Applied Surface Science}, volume = {514}, abstract = {For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to ±5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodium-ion battery electrodes are discussed. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to ±5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodium-ion battery electrodes are discussed. © 2020 |
Puthenkalathil, R C; Etinski, M; Ensing, B Unraveling the mechanism of biomimetic hydrogen fuel production-a first principles molecular dynamics study Journal Article Physical Chemistry Chemical Physics, 22 (19), pp. 10447-10454, 2020. @article{Puthenkalathil202010447, title = {Unraveling the mechanism of biomimetic hydrogen fuel production-a first principles molecular dynamics study}, author = {R C Puthenkalathil and M Etinski and B Ensing}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085263958&doi=10.1039%2fc9cp06770a&partnerID=40&md5=6d9fc138d6bf7706880f82f477c4455b}, doi = {10.1039/c9cp06770a}, year = {2020}, date = {2020-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, number = {19}, pages = {10447-10454}, abstract = {The Fe2(bdt)(CO)6 [bdt = benzenedithiolato] complex, a synthetic mimic of the [FeFe] hydrogenase enzyme can electrochemically convert protons into molecular hydrogen. Molecular understanding of the cascade of reaction steps is important for the design of more efficient catalysts. In this study, we investigate the reaction mechanism of the hydrogen production catalysis in explicit solution of acetonitrile using first principles molecular dynamics simulations. We have characterized all reduction and protonation intermediates taking part in the catalytic cycle. Free energy surfaces of the activated reaction steps are calculated using metadynamics. We find that the second protonation leading to molecular hydrogen formation is the rate limiting step. Direct protonation of the bridging hydride by a proton from the solution to form H2 is the most favorable reaction pathway. However, also a bdt sulfur atom can become protonated, leading to a possible proton trap state that reduces the catalytic efficiency. Our calculations validate the ECEC mechanism proposed using cyclic voltammetry. © 2020 the Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Fe2(bdt)(CO)6 [bdt = benzenedithiolato] complex, a synthetic mimic of the [FeFe] hydrogenase enzyme can electrochemically convert protons into molecular hydrogen. Molecular understanding of the cascade of reaction steps is important for the design of more efficient catalysts. In this study, we investigate the reaction mechanism of the hydrogen production catalysis in explicit solution of acetonitrile using first principles molecular dynamics simulations. We have characterized all reduction and protonation intermediates taking part in the catalytic cycle. Free energy surfaces of the activated reaction steps are calculated using metadynamics. We find that the second protonation leading to molecular hydrogen formation is the rate limiting step. Direct protonation of the bridging hydride by a proton from the solution to form H2 is the most favorable reaction pathway. However, also a bdt sulfur atom can become protonated, leading to a possible proton trap state that reduces the catalytic efficiency. Our calculations validate the ECEC mechanism proposed using cyclic voltammetry. © 2020 the Owner Societies. |
Brkovic, S M; Kaninski, Marceta M P; Lausevic, P Z; Saponjic, A B; Radulovic, A M; Rakic, A A; Pasti, I A; Nikolic, V М International Journal of Hydrogen Energy, 45 (27), pp. 13929-13938, 2020. @article{Brkovic202013929, title = {Non-stoichiometric tungsten-carbide-oxide-supported Pt–Ru anode catalysts for PEM fuel cells – From basic electrochemistry to fuel cell performance}, author = {S M Brkovic and M P Marceta Kaninski and P Z Lausevic and A B Saponjic and A M Radulovic and A A Rakic and I A Pasti and V М Nikolic}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082747239&doi=10.1016%2fj.ijhydene.2020.03.086&partnerID=40&md5=6f42c2081cf1e926f3d3d807bf9b0fb1}, doi = {10.1016/j.ijhydene.2020.03.086}, year = {2020}, date = {2020-01-01}, journal = {International Journal of Hydrogen Energy}, volume = {45}, number = {27}, pages = {13929-13938}, abstract = {Durability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt–Ru–based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E < 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %. © 2020 Hydrogen Energy Publications LLC}, keywords = {}, pubstate = {published}, tppubtype = {article} } Durability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt–Ru–based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E < 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %. © 2020 Hydrogen Energy Publications LLC |
Maksimovic, J P; Tošovic, J; Pagnacco, M C Insight into the origin of pyrocatechol inhibition on oscillating bray-liebhafsky reaction: Combined experimental and theoretical study Journal Article Bulletin of the Chemical Society of Japan, 93 (5), pp. 676-684, 2020. @article{Maksimovic2020676, title = {Insight into the origin of pyrocatechol inhibition on oscillating bray-liebhafsky reaction: Combined experimental and theoretical study}, author = {J P Maksimovic and J Tošovic and M C Pagnacco}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086148155&doi=10.1246%2fbcsj.20190296&partnerID=40&md5=0b720ef8b7ed7a7f6ce0a86d72c3a80f}, doi = {10.1246/bcsj.20190296}, year = {2020}, date = {2020-01-01}, journal = {Bulletin of the Chemical Society of Japan}, volume = {93}, number = {5}, pages = {676-684}, abstract = {The pyrocatechol inhibitory effect on the oscillatory Bray- Liebhafsky (BL) reaction is reported. Obtained results are compared with those available in the literature (R. Cervellati et al, Helvetica Chimica Acta 2001) for Briggs-Rauscher (BR) reaction with pyrocatechol addition. The two orders of magnitude larger calibration curve slope obtained in BR in comparison to BL reaction, suggests that different reactions are responsible for inhibitory effects in these systems. The potential explanation of pyrocatechol behavior is given by employing the ultravioletvisible (UV/VIS) spectroscopy, density functional theory, and coupled cluster computational methods. The last two were employed for the first time to discover potential candidates among unstable chemical species HIO, HIO2, I2O, HOO·, HO·, IO·, IO2·, and I· of the BL (and BR) system for reaction with pyrocatechol. The calculated reaction rate constants for the hydrogen atom transfer reactions between pyrocatechol and free radical intermediates indicate the following order of reactivity: HO· > IO· > HOO· > IO2·. The same order of reactivity is also observed in the case of a thermodynamic investigation. In addition, kinetic insight indicates that the inhibitory behavior of pyrocatechol could not be explained with one particular chemical reaction in the BL (or in the BR) oscillatory system. © 2020 The Chemical Society of Japan.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The pyrocatechol inhibitory effect on the oscillatory Bray- Liebhafsky (BL) reaction is reported. Obtained results are compared with those available in the literature (R. Cervellati et al, Helvetica Chimica Acta 2001) for Briggs-Rauscher (BR) reaction with pyrocatechol addition. The two orders of magnitude larger calibration curve slope obtained in BR in comparison to BL reaction, suggests that different reactions are responsible for inhibitory effects in these systems. The potential explanation of pyrocatechol behavior is given by employing the ultravioletvisible (UV/VIS) spectroscopy, density functional theory, and coupled cluster computational methods. The last two were employed for the first time to discover potential candidates among unstable chemical species HIO, HIO2, I2O, HOO·, HO·, IO·, IO2·, and I· of the BL (and BR) system for reaction with pyrocatechol. The calculated reaction rate constants for the hydrogen atom transfer reactions between pyrocatechol and free radical intermediates indicate the following order of reactivity: HO· > IO· > HOO· > IO2·. The same order of reactivity is also observed in the case of a thermodynamic investigation. In addition, kinetic insight indicates that the inhibitory behavior of pyrocatechol could not be explained with one particular chemical reaction in the BL (or in the BR) oscillatory system. © 2020 The Chemical Society of Japan. |
