Interlock Strategy Enabling Self-stabilized Cu0/+ Catalysts for Broad-Window Aldehyde Electrooxidation with Anodic Hydrogen Production

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.