Effect of Alkali Metal Ions in Electrolytes on the Electrocatalytic Performance of Cobalt Vanadium Oxide

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The oxygen evolution reaction (OER) is key to the operation of various sustainable technologies like water‐splitting devices and metal‐air batteries. Realization of efficient OER depends on robust electrocatalyst materials as well as optimized electrolytes. The cations in electrolytes have a pronounced impact on the kinetics of OER. However, the mechanistic origin of this effect remains poorly addressed. In this study, using cobalt vanadium oxide Co 3 V 2 O 8 (CVO) as a model electrocatalyst, the cation‐dependent OER activity was investigated using fundamental electrochemical study in conjunction with ex situ (electron microscopy and Raman spectroscopy) analyses. The results demonstrate that OER performance is not only affected by surface/bulk reconstruction, but also governed by electrolyte cation adsorption. In situ Raman study in 1 M KOH electrolyte identified the generation of Co‐oxyhydroxide species accompanied by vanadium dissolution, whereas ex situ Raman spectra revealed a more distinct VO bond in catalysts when subjected to 1 M CsOH. While partial amorphization was noticed in LiOH and NaOH systems, structural retention with irregular Co(O)OH domains was observed in CVO after catalysis in KOH and CsOH electrolytes. Electrochemical evaluation further establishes exchange current density as the sole parameter significantly affected due to the presence of different cations, directly correlating with reduced overpotential (320 mV) and extended durability (>12 hr continuous electrolysis). These findings highlight the critical role of electrolyte cations in modulating the intrinsic kinetics of Co 3 V 2 O 8 toward OER electrocatalysts.

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