Adjustable metal-support interaction and interlayer spacing of Pd/MXenes boosting alkyne semi-hydrogenation via enhanced reaction and diffusion

Achieving precise control of reaction selectivity at high conversion levels is crucial for semi-hydrogenation of alkyne. In this study, three kinds of Pd/Nb2C catalysts (NaBH4-Pd/Nb2C, Pyrolysis-Pd/Nb2C, and H2-Pd/Nb2C) with different degree of SMSI were elaborately designed by tailoring the reduction mode of Pd on Nb2C. H2-Pd/Nb2C with the strongest SMSI displayed an exceptional TOF (7263 h−1) of phenylacetylene and high selectivity (93.5 %) towards styrene, achieving a fine equilibrium between high activity and selectivity. The outstanding performance of H2-Pd/Nb2C can be ascribed to the facilitated electron transfer from Nb to Pd, thus forming an electron-rich Pd and specific Pd-Nb2C interface. Moreover, the promotion effect in catalytic activity caused by the expansion of Nb2C layer spacing is linearly related to the molecular diameter of the reactants. With the increase of interlayer spacing, the more significant the enhancement in catalytic activity of Pd/Nb2C catalyst for the substrates with larger diameter.