Substrate‐Triggered Surface Activation for Efficient Electrosynthesis of Potassium Formate

Abstract The electrocatalytic formaldehyde (HCHO) oxidation reaction (FOR) offers a green, energy‐efficient route for simultaneously addressing HCHO pollution and producing potassium formate (HCOOK) under mild conditions. However, current catalyst designs often prioritize Cu 0 ‐based materials, which suffer from limited stability and easy deactivation. Here, a novel “Substrate‐Triggered Surface Activation” mechanism is uncovered, where HCHO spontaneously reduces surface Cu 2+ to catalytically active Cu 0 sites prior to electrolysis. Building on this insight, a heterostructured CuNiO x nanowire catalyst is engineered, where the NiO domain not only facilitates the in situ Cu 0 formation but also stabilizes these active sites during operation. The CuNiO x achieves a high FOR current density of 400 mA cm −2 at just 0.08 V versus RHE and generates 8.81 mmol cm −2 h −1 of HCOOK at 0.40 V versus RHE. Over 10 consecutive cycles (≈5 h), this system produces 3.75 g of solid HCOOK via spontaneous neutralization, eliminating the need for energy‐intensive separation processes. Furthermore, a bifunctional electrosynthesis system is demonstrated that couples anodic FOR with cathodic nitrate reduction, enabling the simultaneous production of value‐added HCOOK and NH 4 Cl at an ultra‐low cell voltage. This work provides new insights into catalyst activation and offers a promising strategy for sustainable chemical manufacturing and environmental remediation.