Nanoporous Cobalt-Doped Fe3P for Boosted Electrochemical Nitrate Reduction

Electrocatalytic nitrate reduction reaction (NO₃RR) offers a sustainable avenue for mitigating nitrate pollution and enabling decentralized ammonia production. However, achieving high efficiency and selectivity remains challenging due to the sluggish multielectron transfer kinetics. Herein, we report a nanoporous Co-Fe₃P catalyst featuring cobalt-doped iron phosphide frameworks that modulate the d band center, thereby optimizing intermediate binding and enhancing catalytic performance. The catalyst delivers a high ammonia yield rate of 24.56 mg h⁻¹ cm⁻² and a Faradaic efficiency of 91.45% at −0.4 V versus reversible hydrogen electrode (RHE) in alkaline media. In situ infrared spectroscopy identifies key intermediates, such as NH₂OH, NO₂⁻, and NH₂, indicative of an associative pathway. Furthermore, when integrated into a Zn–NO₃⁻ battery, the Co-Fe₃P cathode enables a high-power density of 15.83 mW cm⁻² with excellent Faradaic efficiency and cycling stability.