Interface engineering enhances Lewis acidity and activates inert sites to jointly promote nitrate reduction to ammonia

Abstract

Electrocatalytic nitrate reduction to ammonia (NRA) has been considered a highly promising method for "waste to treasure". Herein, a heterogeneous catalyst FeP/Cu₃P/CF enriched with Lewis acid sites was designed for efficient NRA. The faradaic efficiency and NH₃ yield are up to 95.61% and 0.2573 mmol h⁻¹ cm⁻², the NH₃−N selectivity is 95.11%, and the NO₃^–−N conversion is close to 100%. Experimental and theoretical studies verify that the formation of the interface activates the originally inert Fe site and makes it become the second active center in addition to Cu. The charge transfer greatly raises the positive charge density of Fe^δ+ and Cu^δ+ sites, leading to a significant increase in their Lewis acidity, which enables them to interact strongly with the Lewis base NO₃⁻ and improves the NRA performance; meanwhile, the ability of P site with increased negative charge density to capture H enhances, which is beneficial for the subsequent hydrogenation of nitrate reduction. This work provides an approach for designing efficient NRA catalysts through interface engineering strategy.