Functional ladder-like heterojunctions of Mo2C layers inside carbon sheaths for efficient CO2 fixation

The development of two-dimensional heterogeneous catalysts with highly exposed active site areas for heterogeneous catalytic systems is highly promising for achieving the green transformation of small molecules. 2D transition metal carbides (TMCs) show great promise for catalysis and carbon capture but suffer from heavy aggregation and autooxidation. Mass transfer barrier is also a standard problem of lamellar TMCs caused by slight aggregation of layers. Here, we successfully developed a method to prepare “ladder-like” heterojunctions of Mo 2 C layers confined inside nitrogen-rich carbon sheaths (2D-Mo 2 C@NC) via an effective oxygen-diffusion etching strategy, acting as efficient catalysts for CO 2 fixation. The enhanced electron enrichment of the as-integrated 2D-Mo 2 C subunits induced by the Schottky barrier could further keep the exposed Mo 2 C surface from possible autooxidation and aggregation confronted by conventional 2D TMCs. The experimental results and density functional theory (DFT) calculation further demonstrate that electron-rich Mo 2 C could boost the adsorption and activation of CO 2 for universal carbonylation of various diamines, providing a turnover frequency value (TOF) of 10.2 h −1 to produce benzimidazolone, which is 5.2 times of that of the state-of-the-art catalyst in the literature under even critical conditions.