Termination-Accelerated Electrochemical Nitrogen Fixation on Single-Atom Catalysts Supported by MXenes.

The synthesis of ammonia (NH) from nitrogen (N) under ambient conditions is of great significance but hindered by the lack of highly efficient catalysts. By performing first-principles calculations, we have investigated the feasibility for employing a transition metal (TM) atom, supported on TiCT MXene with O/OH terminations, as a single-atom catalyst (SAC) for electrochemical nitrogen reduction. The potential catalytic performance of TM single atoms is evaluated by their adsorption behavior on the MXene, together with their ability to bind N and to desorb NH molecules. Of importance, the OH terminations on TiCT MXene can effectively enhance the N adsorption and decrease the NH adsorption for single atoms. Based on proposed criteria for promising SACs, our calculations further demonstrate that the Ni/TiCO(OH) exhibits reasonable thermodynamics and kinetics toward electrochemical nitrogen reduction.