Cu<sub>3</sub>P/CoP\nHeterostructure for Efficient\nElectrosynthesis of Ammonia from Nitrate Reduction Reaction

Electrocatalytic nitrate reduction (ENO<sub>3</sub>RR)\nfor ammonia\nproduction is one of the potential alternatives to Haber–Bosch\ntechnology for the realization of artificial ammonia synthesis. However,\nefficient ammonia production remains challenging due to the complex\nelectron transfer process in ENO<sub>3</sub>RR. In this study, we\nfabricated a Cu<sub>3</sub>P/CoP heterostructure on carbon cloth (CC)\nby electrodeposition and vapor deposition, which exhibits an exceptional\nENO<sub>3</sub>RR performance in alkaline medium, and showcases a\nFaradaic efficiency of ammonia (FE<sub>NH<sub>3</sub></sub>) and an\nammonia yield rate as high as 97.95% and 17,637.3 μg h<sup>–1</sup> cm<sup>–2</sup> at −0.9 V vs RHE. Moreover, Cu<sub>3</sub>P/CoP also has excellent catalytic activity for nitrite reduction\nto ammonia, with an FE<sub>NH<sub>3</sub></sub> up to 98.31% at −0.7\nV vs RHE. The experimental and theoretical calculations reveal and\nconfirm that the formation of a heterogeneous interface between Cu<sub>3</sub>P and CoP effectively promotes the electron transfer, where\nCu<sub>3</sub>P as an electron donor induces the decrease of electron\ndensity around Cu and results in an enhancement of NO<sub>2</sub><sup>–</sup> adsorption, thereby accelerating the ENO<sub>3</sub>RR process while inhibiting the competitive hydrogen evolution reaction\n(HER). Moreover, the metal phosphide catalyst facilitates the water\ndissociation, which accelerates the abundant *H generation, thus enhancing\nthe subsequent hydrogenation process toward ENO<sub>3</sub>RR.