Engineering MXenes for Thermal and Photothermal Catalysis

Abstract

Heterogeneous catalysis relies on advanced, tunable materials offering structurally defined active sites and large accessible surface areas. Among the various material types, two-dimensional nanomaterials with high aspect ratios feature a high fraction of exposed atoms and thus efficient atom utilization. After more than a decade since the first report of MXene synthesis, these two-dimensional transition-metal carbides and nitrides, composed of alternating one-atom-thick metal and carbide/nitride layers with surface terminations, have found applications in diverse catalytic areas. This review focuses on the use of MXenes as solid catalysts in thermal or photothermal reactions, while electro- and photocatalysis are excluded as they have been extensively reviewed elsewhere. Section 2 briefly summarizes MXene synthesis and structural features, followed by Section 3 describing the nature and characterization of catalytically active sites, including surface groups, vacancies, and metal-support interfaces that arise from the synthesis conditions. Section 4 emphasizes best practices for ensuring reproducible and stable catalytic performance, with turnover frequency as a key comparative metric. Sections 5 and 6 highlight some representative thermal and photothermal reactions, underscoring the high light-to-heat conversion efficiency of MXenes. This review concludes with current challenges and future prospects, anticipating rapid progress with MXene-based heterogeneous catalysis.