TY  - JOUR
AU  - Rajić, Vladimir
AU  - Stojković-Simatović, Ivana
AU  - Veselinović, Ljiljana
AU  - Belosević-Cavor, Jelena
AU  - Novaković, Mirjana
AU  - Popović, Maja
AU  - Skapin, Sreco Davor
AU  - Mojović, Milos
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Janković-Castvan, Ivona
AU  - Marković, Smilja
PY  - 2020
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5324
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 Zn(2+)partial substitution with Fe(3+)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 Vvs.RHE), current density (0.231 mA cm(-2)at 0.150 Vvs.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 (0001x304;) facets. Quite the contrary, the OER study showed that the introduction of Fe(3+)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 Vvs.RHE, an onset potential of 1.856 Vvs.RHE, and the smallest potential difference between the OER and ORR (Delta E= 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.
PB  - Royal Soc Chemistry, Cambridge
T2  - Physical Chemistry Chemical Physics
T1  - Bifunctional catalytic activity of Zn1-xFexO toward the OER/ORR: seeking an optimal stoichiometry
EP  - 22095
IS  - 38
SP  - 22078
VL  - 22
DO  - 10.1039/d0cp03377d
ER  - 

@article{
author = "Rajić, Vladimir and Stojković-Simatović, Ivana and Veselinović, Ljiljana and Belosević-Cavor, Jelena and Novaković, Mirjana and Popović, Maja and Skapin, Sreco Davor and Mojović, Milos and Stojadinović, Stevan and Rac, Vladislav and Janković-Castvan, 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 Zn(2+)partial substitution with Fe(3+)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 Vvs.RHE), current density (0.231 mA cm(-2)at 0.150 Vvs.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 (0001x304;) facets. Quite the contrary, the OER study showed that the introduction of Fe(3+)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 Vvs.RHE, an onset potential of 1.856 Vvs.RHE, and the smallest potential difference between the OER and ORR (Delta E= 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.",
publisher = "Royal Soc Chemistry, Cambridge",
journal = "Physical Chemistry Chemical Physics",
title = "Bifunctional catalytic activity of Zn1-xFexO toward the OER/ORR: seeking an optimal stoichiometry",
pages = "22095-22078",
number = "38",
volume = "22",
doi = "10.1039/d0cp03377d"
}

Rajić, V., Stojković-Simatović, I., Veselinović, L., Belosević-Cavor, J., Novaković, M., Popović, M., Skapin, S. D., Mojović, M., Stojadinović, S., Rac, V., Janković-Castvan, I.,& Marković, S.. (2020). Bifunctional catalytic activity of Zn1-xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics
Royal Soc Chemistry, Cambridge., 22(38), 22078-22095.
https://doi.org/10.1039/d0cp03377d

Rajić V, Stojković-Simatović I, Veselinović L, Belosević-Cavor J, Novaković M, Popović M, Skapin SD, Mojović M, Stojadinović S, Rac V, Janković-Castvan 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, Stojković-Simatović, Ivana, Veselinović, Ljiljana, Belosević-Cavor, Jelena, Novaković, Mirjana, Popović, Maja, Skapin, Sreco Davor, Mojović, Milos, Stojadinović, Stevan, Rac, Vladislav, Janković-Castvan, 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 . .