Interlock Strategy Enabling Self‐stabilized Cu ^0/+ Catalysts for Broad‐Window Aldehyde Electrooxidation with Anodic Hydrogen Production

ABSTRACT Substituting the oxygen evolution reaction with formaldehyde oxidation in aqueous electrochemical systems can simultaneously reduce energy consumption and yield value‐added products such as hydrogen and formic acid. However, Cu‐based catalysts suffer from oxidative deactivation, limiting their electrochemical window (<0.6 V) and compromising activity and stability. Herein, a dynamic self‐stabilization strategy for formaldehyde electrooxidation at high potentials, where high‐coverage HCHO species stabilizes Cu 0/+ catalysts to sustain continuous catalysis, is proposed. This approach extends the reaction potential window beyond 1 V, achieving ampere‐level current densities. Quasi‐in‐situ Raman spectroscopy and in situ X‐ray absorption spectroscopy confirm Cu 0 as the primary active site across a broad potential range. In situ infrared spectroscopy and density functional theory calculations reveal that the Cu + enhances formaldehyde adsorption at high potentials while suppressing excessive OH − coverage, mitigating oxidative deactivation and boosting catalyst stability. Moreover, using this Cu 0/+ electrocatalyst, this study develops a non‐noble‐metal‐based bipolar hydrogen production device, delivering 10 A at 0.6 V with near‐unity Faradaic efficiency for both hydrogen and formate production. This work offers a robust framework for expanding the redox potential window of organic molecule electrooxidation.