Bimetallic Cu-Fe catalysts on MXene for synergistically electrocatalytic conversion of nitrate to ammonia

NO₃^- is a common water pollutant that can serve as a potential nitrogen source for electrocatalytic NH₃ production. However, an efficient and complete removal of low NO₃^- concentrations remains a challenge. Fe₁Cu₂@MXene bimetallic catalysts were constructed on two-dimensional Ti₃C₂T_x MXene carriers via a simple solution-based synthetic method and used for the electrocatalytic reduction of NO₃^-. The combination of the rich functional groups, high electronic conductivity on the MXene surface, and the synergistic effect between the Cu and Fe sites enabled the composite to effectively catalyse NH₃ synthesis, with a 98% conversion of NO₃^- in 8 h and a selectivity for NH₃ of up to 99.6%. In addition, Fe₁Cu₂@MXene showed excellent environmental and cyclic stability at various pH values and temperatures over multiple (14) cycles. Semiconductor analysis techniques and electrochemical impedance spectroscopy confirmed that the synergistic effect provided by the dual active sites of the bimetallic catalyst enabled fast electron transport. This study provides new insights into the synergistic promotion of NO₃^- reduction reactions using bimetals.