Self‐Cleaning Copper Nanorods via Periodic Valence Transitions: Overcoming Formate Accumulation for Industrial‐Grade Formaldehyde Electrooxidation

Abstract Copper‐based electrocatalysts demonstrate superior activity for formaldehyde electrooxidation reaction (FOR). However, the self‐oxidation of copper restricts the potential window for FOR, resulting in reduced current densities and hydrogen evolution rates. Herein, copper nanorods (Cu NRs) are engineered with abundant active sites through morphology‐controlled synthesis, achieving superior FOR performance. The Cu NRs deliver an industrial current density of 1150 mA cm −2 at 1.25 V vs. RHE along with a broad operational window of –0.1–1.25 V vs. RHE. In situ spectroscopic investigations techniques reveal that the primary cause of deactivation in Cu NRs is the accumulation of formate intermediates at active sites, as the primary stability bottleneck. To address this issue, a universal dynamic self‐cleaning protocol is proposed, which proactively engineers “electrochemical oxidation” and “formaldehyde‐induced reduction” cycle to disrupt formate intermediate adsorption. Moreover, the entire process operates in a noble metal‐free system, which achieving intrinsic regeneration via controlled valence transition cycle (Cu 0 ↔ Cu + /Cu 2+ ). This strategy enables a bipolar hydrogen‐producing “Cu NRs||Pt/C” electrolyzer to achieve outstanding cycle stability (26 cycles for 208 h), outperforming most reported Cu‐based systems. By coupling nanoscale morphology engineering with operando‐guided surface reactivation, this work establishes a universal paradigm for designing durable electrocatalysts plagued by intermediate poisoning.