Highly Efficient Electrochemical Reduction of Nitrogen to Ammonia on Surface Termination Modified Ti₃C₂T_<i>x</i> MXene Nanosheets

Abstract

MXene-based catalysts exhibit extraordinary advantages for many catalysis reactions, such as the hydrogen evolution and oxygen reduction reactions. However, MXenes exhibit inadequate catalytic activity for the electrochemical nitrogen reduction reaction (NRR) because they are typically terminated with inactive functional groups, F* and OH*, which mask the active metal sites for N2 binding. Here we modified the surface termination of MXene (Ti3C2Tx) nanosheets to achieve high surface catalytic reactivity for the NRR by ironing out inactive F*/OH* terminals to expose more active sites and by introducing Fe to greatly reduce the surface work function. The optimally performing catalyst (MXene/TiFeOx-700) achieved excellent Faradaic efficiency of 25.44% and an NH3 yield rate of 2.19 μg/cm2·h (21.9 μg/mgcat·h), outperforming all reported MXene-based NRR catalysts. Our work provides a feasible strategy for rationally improving the surface reactivity of MXene-based catalysts for efficient electrochemical conversion of N2 to NH3.