TY  - JOUR
AU  - Rajić, Vladimir
AU  - Simatović Stojković, Ivana
AU  - Veselinović, Ljiljana M.
AU  - Belošević-Čavor, Jelena
AU  - Novaković, Mirjana M.
AU  - Popović, Maja
AU  - Škapin, Srečo Davor
AU  - Mojović, Miloš
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Častvan Janković, Ivona
AU  - Marković, Smilja
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9679
AB  - Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.
T2  - Physical Chemistry Chemical Physics
T1  - Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry
VL  - 22
IS  - 38
SP  - 22078
EP  - 22095
DO  - 10.1039/D0CP03377D
ER  - 

@article{
author = "Rajić, Vladimir and Simatović Stojković, Ivana and Veselinović, Ljiljana M. and Belošević-Čavor, Jelena and Novaković, Mirjana M. and Popović, Maja and Škapin, Srečo Davor and Mojović, Miloš and Stojadinović, Stevan and Rac, Vladislav and Častvan Janković, Ivona and Marković, Smilja",
year = "2020",
abstract = "Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.",
journal = "Physical Chemistry Chemical Physics",
title = "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry",
volume = "22",
number = "38",
pages = "22078-22095",
doi = "10.1039/D0CP03377D"
}

Rajić, V., Simatović Stojković, I., Veselinović, L. M., Belošević-Čavor, J., Novaković, M. M., Popović, M., Škapin, S. D., Mojović, M., Stojadinović, S., Rac, V., Častvan Janković, I.,& Marković, S.. (2020). Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics, 22(38), 22078-22095.
https://doi.org/10.1039/D0CP03377D

Rajić V, Simatović Stojković I, Veselinović LM, Belošević-Čavor J, Novaković MM, Popović M, Škapin SD, Mojović M, Stojadinović S, Rac V, Častvan Janković I, Marković S. Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics. 2020;22(38):22078-22095.
doi:10.1039/D0CP03377D .

Rajić, Vladimir, Simatović Stojković, Ivana, Veselinović, Ljiljana M., Belošević-Čavor, Jelena, Novaković, Mirjana M., Popović, Maja, Škapin, Srečo Davor, Mojović, Miloš, Stojadinović, Stevan, Rac, Vladislav, Častvan Janković, Ivona, Marković, Smilja, "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry" in Physical Chemistry Chemical Physics, 22, no. 38 (2020):22078-22095,
https://doi.org/10.1039/D0CP03377D . .