Keggin-type P-W-Mo-V polyoxometalates in electrocatalyzed CO₂ reduction using indium electrodes

Electrochemical CO₂ reduction reaction (CO₂RR) driven by indium-based catalysts can convert CO₂ into C1 products with specific energy densities and relatively low mass. However, it is promising to obtain C2 products by introducing Keggin-type polyoxometalates (POMs) that can effectively regulate the proton-coupled electron transfer at the electrode–electrolyte interface. Here, the commercial indium sheets were combined with Keggin-type POMs (H₄PVMoW₁₀O₄₀·15H₂O, PVMoW₁₀; H₅PV₂MoW₉O₄₀·10H₂O, PV₂MoW₉) to process CO₂RR. The highest Faradaic efficiency (FE) toward acetate reached 75.6% in the PVMoW₁₀ system, and the highest FE_ethanol reached 85.1% in the PV₂MoW₉ system. The X-ray photoelectron spectroscopy (XPS) results indicated that the electron transfer by the POMs had a positive interaction with the active In⁰ sites, which provided a special electron channel to improve the FEs of the C2 products in CO₂RR.