Recent advances in structural engineering of MXene electrocatalysts

Most recently, two-dimensional (2D) transition-metal carbides (MXenes) have been demonstrated to be promising electrocatalysts owing to their unique chemical and electronic properties, e.g., metallic conductivity, high hydrophilicity, and tunable surface terminations. Herein, representative progress achieved in MXenes as hydrogen evolution reaction electrocatalysts is reviewed both experimentally and theoretically. Briefly, termination modification and heteroatom incorporation are applied to optimize the chemical and electronic configurations of active sites for intrinsically enhanced catalytic kinetics while various nanostructures and hybridizations are fabricated to increase the density and accessibility of active sites. Then, the achievements of MXene-based catalysts in other electrocatalysis processes are also summarized, including the oxygen evolution/reduction reaction, carbon dioxide reduction reaction and nitrogen reduction reaction. Finally, current challenges and future research directions for MXene-based electrocatalysis are discussed.