TY - JOUR
T1 - Bias-induced surface reconstruction of a MOF-derived bimetallic (Co & V) oxide as an electrocatalyst for water oxidation
AU - Sahoo, Malaya K.
AU - Bishoyi, Nisarani
AU - Swain, Deepak K.
AU - Behera, J. N.
N1 - Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022/1/1
Y1 - 2022/1/1
N2 - The four-electron oxygen evolution reaction (OER) is the bottleneck in the overall water splitting process, which needs to be addressed for the better hydrogen economy of an electrolyzer. In this work, a bimetallic metal-organic framework with the formula [Co(C4H4N2)(VO3)2] was annealed at 500, 600, and 700 °C in an argon atmosphere to yield CoV@500, CoV@600, and CoV@700, respectively. The high-temperature annealing leads to the generation of heterostructured nanoparticles of crystalline spinel oxide Co2VO4 and amorphous VOx wrapped with a carbon and nitrogen matrix. CoV@600 exhibits superior OER performance to afford the state-of-the-art current density of 10 mA cm−2 at a lower overpotential of 273 mV and a small Tafel slope of 54.32 mV dec−1 that outperformed the benchmark electrocatalyst RuO2 and other catalysts used here. The superior OER performance could be ascribed to the lower charge transfer resistance, presence of oxygen vacancy, and lattice defects. Interestingly, the long-term chronopotentiometric stability exhibits a lowering in the overpotential with time, and a detailed investigation of the catalyst after OER manifests the leaching of the amorphous vanadium oxide and oxidation of Co(ii) to Co(iii) induced by the potential bias. Leaching triggers the surface decoration of cobalt oxyhydroxide (CoOOH) with core spinel oxide (Co2VO4) as confirmed from XPS, TEM, FESEM, and PXRD techniques. Further, accelerated degradation studies and the LSV after the 1000th cycle present a lowered overpotential of 241 mV at 10 mA cm−2 current density. The synergistic effect between the active CoOOH surface and defect-rich core spinel oxide could be the origin of the enhanced OER performance. This work not only presents superior OER performance of the annealed product of the framework but also demonstrates a strategy to obtain in situ bias-induced surface modification and emphasizes the importance of the postmortem analysis of a catalyst after catalysis.
AB - The four-electron oxygen evolution reaction (OER) is the bottleneck in the overall water splitting process, which needs to be addressed for the better hydrogen economy of an electrolyzer. In this work, a bimetallic metal-organic framework with the formula [Co(C4H4N2)(VO3)2] was annealed at 500, 600, and 700 °C in an argon atmosphere to yield CoV@500, CoV@600, and CoV@700, respectively. The high-temperature annealing leads to the generation of heterostructured nanoparticles of crystalline spinel oxide Co2VO4 and amorphous VOx wrapped with a carbon and nitrogen matrix. CoV@600 exhibits superior OER performance to afford the state-of-the-art current density of 10 mA cm−2 at a lower overpotential of 273 mV and a small Tafel slope of 54.32 mV dec−1 that outperformed the benchmark electrocatalyst RuO2 and other catalysts used here. The superior OER performance could be ascribed to the lower charge transfer resistance, presence of oxygen vacancy, and lattice defects. Interestingly, the long-term chronopotentiometric stability exhibits a lowering in the overpotential with time, and a detailed investigation of the catalyst after OER manifests the leaching of the amorphous vanadium oxide and oxidation of Co(ii) to Co(iii) induced by the potential bias. Leaching triggers the surface decoration of cobalt oxyhydroxide (CoOOH) with core spinel oxide (Co2VO4) as confirmed from XPS, TEM, FESEM, and PXRD techniques. Further, accelerated degradation studies and the LSV after the 1000th cycle present a lowered overpotential of 241 mV at 10 mA cm−2 current density. The synergistic effect between the active CoOOH surface and defect-rich core spinel oxide could be the origin of the enhanced OER performance. This work not only presents superior OER performance of the annealed product of the framework but also demonstrates a strategy to obtain in situ bias-induced surface modification and emphasizes the importance of the postmortem analysis of a catalyst after catalysis.
UR - http://www.scopus.com/inward/record.url?scp=85139973297&partnerID=8YFLogxK
U2 - 10.1039/d2se00970f
DO - 10.1039/d2se00970f
M3 - Article
AN - SCOPUS:85139973297
SN - 2398-4902
JO - Sustainable Energy and Fuels
JF - Sustainable Energy and Fuels
ER -