Accelerating H* Redistribution via Hydrogen Spillover for Enhanced Electrochemical Hydrogen Production From Formaldehyde

Producing hydrogen from formaldehyde oxidation reaction (FOR) offers a promising low‐energy approach for generating clean fuel. However, the FOR involves continuous C─H bond cleavage of adsorbed intermediates to generate abundant surface H*. This necessitates rapid transfer and consumption of H* to sustain fast oxidation kinetics. Herein, we developed a hydrogen‐spillover strategy to redistribute these surface H* to accelerate FOR kinetics by constructing RhCu single‐atom alloy supported on a Cu single‐atom‐rich carbon matrix (RhCu@Cu SA NC). In this design, Cu incorporation creates a favorable landscape for H* migration toward the Cu SA NC support, which acts as efficient H* acceptors and H─H coupling centers. Verified through multiple analyses, this hydrogen‐spillover mechanism is demonstrated to enhance FOR activity by accelerating H* redistribution. Consequently, RhCu@Cu SA NC shows outstanding FOR performance, achieving a current density of 800 mA cm − 2 at 0.39 V with nearly 100% H 2 selectivity and excellent durability. When integrated into a hybrid alkali‐acid cell, it provides an open circuit voltage of 1.72 V and peak power density of 152.6 mW cm − 2 with stable H 2 production for over 1200 h at 10 mA cm − 2 . These results demonstrate that hydrogen spillover boosts oxidative electrocatalysis, providing a general design principle for multicomponent catalysts with coordinated hydrogen dynamics.