Synthesis of MXene-based single-atom catalysts for energy conversion applications

High atomic utilization of single atom catalysts (SACs) have the advantages of high catalytic performance and high selectivity. The characteristics of "independent active site" and "easy recycling" of heterogeneous catalysts can effectively solve the deficiencies of precious-metal catalysts for energy conversion applications. However, to get the full advantages of SACs, the role of anchoring sites and supports is critically significant. The anchoring supports enhanced the stability of isolated atoms as well as affected its electronic assembly, thereby affecting the catalytic performance. MXenes are emergent new 2D materials with the characteristics of high specific surface area, adjustable band gap, good conductivity and rich chelating sites, an ideal support material for SACs. This paper briefly summarized the structural characteristics of MXene, reviewed the preparation strategies of MXenebased SACs, and emphasized the energy conversion applications of MXene-based SACs by discussing the small molecular reactions, including O2/H2 evolution reaction, O2/CO2/N2 reduction reactions as well as bi-functional SACs for the water-splitting and rechargeable metal-air batteries. Finally, the current challenges and opportunities are summarized in synthesis of MXene-based SACs and energy conversion applications.