Pulsed Laser-Initiated Dual-Catalytic Interfaces for Directed Electroreduction of Nitrite to Ammonia

Abstract

Green and highly selective synthesis of ammonia (NH₃) via electrochemical reduction reaction of toxic nitrite (NO₂⁻RR) in a neutral electrolyte is a feasible solution for energy and environmental issues. Dual-nature electrocatalysts combining metal and metal-derived materials are crucial for enhancing the selectivity parameter and efficacy of this reaction. Here, Pd-, Pt-, Ru-, and Ir-decorated Co₃(PO₄)₂ (CoPi) composites with a robust metal–support interaction are obtained via the one-pot pulsed laser ablation in liquid method. Among the designed composites, Ir–CoPi affords ≈100% Faradaic efficiency, mass balance, and selectivity toward NH₃ product at sufficiently low potentials. Further, it affords the highest NH₃ yield rate of 19.13 mg h⁻¹ cm⁻² with 78.1% removal of toxic NO₂⁻ with a rate constant k_app = 0.31 mm min⁻¹ under −1.6 V versus Ag/AgCl. In situ experiments and theoretical investigations reveal the underlying mechanisms responsible for this outstanding performance of Ir–CoPi, which can be accredited to the generation of specific active sites on the Ir component. Insights derived from the evolving intermediate reactive species provide new opportunities for large-scale NH₃ production through electrochemical techniques, density functional theory calculations, and the improvement of the corresponding industrial processes.