Tripodal Pd metallenes mediated by Nb2C MXenes for boosting alkynes semihydrogenation

Abstract

2D metallene nanomaterials have spurred considerable attention in heterogeneous catalysis by virtue of sufficient unsaturated metal atoms, high specific surface area and surface strain. Nevertheless, the strong metallic bonding in nanoparticles aggravates the difficulty in the controllable regulation of the geometry of metallenes. Here we propose an efficient galvanic replacement strategy to construct Pd metallenes loaded on Nb2C MXenes at room temperature, which is triggered by ultra-strong metal-support interaction based on MD simulation. A combination of electron microscopy, synchrotron X-ray absorption spectroscopy characterizations and theoretical calculations confirm that the Pd metallenes feature a chair structure of six-membered ring with the coordination number of Pd as low as 3. The tripodal Pd metallenes promote the diffusion of alkenes as the effective Pd atoms directly bonded with alkenes decreased compared with traditional Pd (111). As a consequence, the Pd/Nb2C delivers an outstanding turnover frequency of 10372 h− 1 and a high selectivity of 96% at 25 oC in the semihydrogenation of alkynes without compromising the stability. This strategy is general and scalable considering the plentiful members of the MXene family, which can set a foundation for the design of novel supported-metallene catalysts for demanding transformations.