Strong electron coupling of FeP4/Ni2P to boost highly-efficient electrochemical nitrate reduction to ammonia.

ABSTRACT

Electrochemical reduction of contaminated nitrate to ammonia (NRA) opens a new window for mass production of ammonia and the alleviation of energy crises and environmental pollution. However, fabricating effective catalysts for the NRA still faces significant challenges. Herein, a highly-efficient NRA catalyst, FeP4/Ni2P, was successfully constructed. The strong electron coupling at heterointerfaces of FeP4/Ni2P promoted the generation of abundant active hydrogen *H, inhibited the competition of the HER, accelerated the hydrogenation of the NRA. Benefiting from these, the catalyst displays good NRA catalytic activity in the neutral electrolyte, with the NH3 FE of 97.83 ± 0.091 %, NH3 selectivity of 98.67 ± 0.50 %, NH3 yield rate of 0.262 ± 0.01 mmol·h-1·cm-2, and NO3- conversion rate of 93.02 ± 0.14 %. The DFT theoretical calculations demonstrated that the FeP4/Ni2P heterointerfaces played a critical role in shearing the H-OH bonds of water, resulting in generating more active hydrogen as a key NRA hydrogenation source, and hindering the *H dimerization to form H2, enhancing the NH3 selectivity. This work has a certain reference value for designing excellent catalysts for the NRA.