Interface Modulation Boosts Nitrate Reduction Performance of Iron-based Catalysts

Abstract

Electrocatalytic nitrate reduction to ammonia (e-NO3RR) is a key technology for the synthesis of green ammonia. This study presents an ingenious interface regulation strategy, constructing a Fe@CN core–shell electrocatalyst for e-NO3RR via facile one-step pyrolysis method. This unique architecture not only provides physical protection for the Fe cores, significantly enhancing their stability, but also optimizes the electronic structure of the active centers through strong electronic interaction between Fe and the CN shell. The reaction mechanism and origin of activity are systematically elucidated through in situ characterization and density functional theory calculations, confirming that the CN shell effectively weakens hydrogen adsorption to suppress the competing hydrogen evolution reaction while lowering the energy barriers of key elementary steps. Electrochemical tests demonstrate that Fe@CN achieves a Faradaic efficiency of 97.2% and an NH3 yield rate of 0.603 mmol h⁻1 cm⁻2 at -0.4 V vs. RHE, maintaining efficiency above 90% across a broad potential window from -0.3 to -0.5 V vs. RHE, along with outstanding long-term stability over 105 h. This work reveals the critical role of interfacial microenvironment regulation in optimizing reaction pathways, providing new insights and strategies for designing highly efficient and stable iron-based electrocatalysts.