Ultra-low potential formaldehyde electrooxidation to formate and H₂ on an Ag/Ag₂O heterostructure catalyst

Formaldehyde oxidation reaction (FOR) is a promising reaction alternative to the anodic oxygen evolution reaction (OER) owing to its ultra-low electrolysis potential and ability to produce formate and hydrogen gas. In this work, the electrode for FOR is prepared using Ag/Ag₂O nanoparticles (Ag/Ag₂O NPs) covered with Nafion membrane as the catalysts modified onto nickel foam (NF). Ag/Ag₂O NPs@NF exhibits significantly higher FOR activity than Ag NPs@NF and Ag₂O NPs@NF. At 100 mA·cm⁻², the FOR potential on the Ag/Ag₂O NPs@NF electrode is only 0.16 V (vs. RHE). Meanwhile, the Faradaic efficiencies can reach up to 100% for both formate and H₂ produced by FOR. Density functional theory (DFT) calculations indicate that the Ag/Ag₂O heterostructure exhibits lower reaction energy barriers for generating formate and H₂ than pure Ag and Ag₂O. This work introduces a new synthetic approach for developing novel FOR catalysts and offers insights into the potential application prospects of FOR.