Facile Construction of CuFe-Based Metal Phosphides for Synergistic NO x - Reduction to NH 3 and Zn-Nitrite Batteries in Electrochemical Cell.

The electrocatalytic nitrite/nitrate reduction reaction (eNO 2 RR/eNO 3 RR) offer a promising route for green ammonia production. The development of low cost, highly selective and long-lasting electrocatalysts for eNO 2 RR/eNO 3 RR is challenging. Herein, a method is presented for constructing Cu 3 P-Fe 2 P heterostructures on iron foam (CuFe-P/IF) that facilitates the effective conversion of NO 2 - and NO 3 - to NH 3 . At -0.1 and -0.2 V versus RHE (reversible hydrogen electrode), CuFe-P/IF achieves a Faradaic efficiency (FE) for NH 3 production of 98.36% for eNO 2 RR and 72% for eNO 3 RR, while also demonstrating considerable stability across numerous cycles. The superior performance of CuFe-P/IF catalyst is due tothe rich Cu 3 P-Fe 2 P heterstuctures. Density functional theory calculations have shed light on the distinct roles that Cu 3 P and Fe 2 P play at different stages of the eNO 2 RR/eNO 3 RR processes. Fe 2 P is notably active in the early stages, engaging in the capture of NO 2 - /NO 3 - , O─H formation, and N─OH scission. Conversely, Cu 3 P becomes more dominant in the subsequent steps, which involve the formation of N─H bonds, elimination of OH * species, and desorption of the final products. Finally, a primary Zn-NO 2 - battery is assembled using CuFe-P/IF as the cathode catalyst, which exhibits a power density of 4.34 mW cm -2 and an impressive NH 3 FE of 96.59%.