Optimized Intermediates Adsorption Configuration on Co‐Doped Fe₂P@NiP₂ Heterojunction Interface for Enhanced Electrocatalytic Nitrate‐To‐Ammonia Conversion

Abstract

The extraction of ammonia (NH₃) through electrocatalytic nitrate reduction reaction (NO₃ ^-RR) represents a sustainable avenue in NH₃ generation and utilization. However, the catalytic efficiency of the NO₃ ^-RR is hindered by the sluggish kinetics. This study first theoretically found that phosphide-based heterostructure can alter the adsorption structure of intermediates in the nitrate-to-ammonia process, thereby achieving precise regulation of the energy barrier in the rate-determining step. Based on theoretical design, a novel Co-doped Fe₂P@NiP₂ heterojunction catalyst is successfully synthesized, which deliver a notable NH₃ yield rate of 0.395 mmol h^-1 cm^-2 at -0.7 V versus RHE, as well as a remarkable ammonia Faraday efficiency of 97.2% at -0.6 V versus RHE. Experimental and theoretical results further confirm that redistributing electrons and shifting the center of the d-band upwards through interfacial doping modulate intermediates adsorption strength and inhibition of hydrogen evolution, leading to excellent performance in NO₃ ^--to-NH₃. Further integrating the Co-Fe₂P@NiP₂ catalyst into a Zn-nitrate battery exhibits a substantial voltage output of 1.49 V and a commendable power density of 13.2 mW cm^-2. The heteroatom-doped heterojunction strategy provides a versatile route for developing advanced catalysts, thereby broadening the horizons of electrocatalytic methodologies for nitrate reduction and ammonia synthesis.