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. •Medium entropy alloy nanoparticles in ordered mesoporous carbons are prepared.•The catalyst shows NO₃⁻ conversion of 91 % and NH₃ selectivity of 89 %.•Zn-evaporation-induced vacancies synergize with MEA, enhancing eNRA performance.