Modulating Silver Performance in Electrocatalytic Oxidation of HCHO via SMSI between Ag‐Co₃O₄ Interfaces

Abstract The replacement of oxygen evolution reactions with organic molecule oxidation reactions to enable energy‐efficient hydrogen production has been a subject of interest. However, further reducing reaction energy consumption and releasing hydrogen from organic molecules continue to pose significant challenges. Herein, a strategy is proposed to produce hydrogen and formic acid from formaldehyde using Ag/Co₃O₄ interface catalysts at the anode. The key to improving the performance of Ag‐based catalysts for formaldehyde oxidation lies in the strong SMSI achieved through the well‐designed “spontaneous redox reaction” between Ag and Co₃O₄ precursors. Nano‐sized Ag particles are uniformly dispersed on Co₃O₄ nanosheets, and electron‐deficient Ag^δ+ are formed by the SMSI between Ag and Co₃O_4. Ag/Co₃O₄ demonstrates exceptional formaldehyde oxidation activity at low potentials of 0.32 V versus RHE and 0.65 V versus RHE, achieving current densities of 10 and 100 mA cm⁻², respectively. The electrolyzer “Ag/Co₃O₄||20% Pt/C” achieves over 195% hydrogen efficiency and over 98% formic acid selectivity, maintaining stable operation for 60 hours. This work not only presents a novel approach to precisely modulate Ag particle size and interface electronic structure via SMSI, but also provides a promising approach to efficient and energy‐saving hydrogen production and the transformation of harmful formaldehyde.