Medium entropy alloy nanoparticles incorporated in ordered mesoporous carbons for enhanced electrocatalytic nitrate-to-ammonia conversion

Electrocatalytic reduction of nitrate (NO3-) to ammonia (NH3) (eNRA) offers a promising method to transform harmful nitrate into valuable ammonia. However, this conversion is often hindered by limited adsorption of nitrate and the challenge of regulating active hydrogen (*H) generation on cathode surfaces. In this work, ordered mesoporous carbon supported medium entropy alloy (MEA) nanocatalysts are prepared for eNRA. The resulting FeCoNiCu(Zn)@MC exhibits high electrochemical eNRA performance, achieving nitrate conversion of 91.1 % and NH3 selectivity of 89 %, as well as long-term stability. This excellent performance can be attributed to the vacancies generated from zinc vaporization during the preparation of MEA, which facilitates the adsorption of NO3-, while MEA promotes the formation of *H, favoring further hydrogenation for selective NH3 generation. Additionally, mesopores of the support promote the mass transfer of NO3-, disperses the MEA nanocatalysts and accelerates the reaction process. This work advances the development of MEA nanocatalysts and expands the eNRA catalysts for nitrate reduction and ammonia synthesis.