Water-assisted proton hopping (WAPH) has been intensively investigated for promoting the performance of metal oxide-supported catalysts for hydrogenation. However, the effects of the structure of the metal oxide support on WAPH have received little attention. Herein, we construct oxygen vacancy-bearing, MoO3–x -supported Pd nanoparticle catalysts (Pd/MoO3–x -R), where the oxygen vacancies can promote WAPH, thereby facilitating catalytic hydrogenation. The experimental results and theoretical calculations show that the oxygen vacancies favor the adsorption of water, which assists the proton hopping across the surface of the metal oxide, enhancing the catalytic hydrogenation. Our finding will provide a potential approach to the design of metal oxide-supported catalysts for hydrogenation.

Ru-based catalysts hold great promise for selective hydrogenation of quinolines. However, the slow desorption of active H and strong adsorption of hydrogenated substrates on the Ru active sites seriously hinder their industrial applications. Herein, we design Ti3C2T x -supported Ru nanocluster catalysts by loading Ru nanoclusters on two-dimensional (2D) Ti3C2T x nanosheets. The Ti3C2T x nanosheets with unique 2D structure and rich surface-terminated functional groups afford the formed Ru nanoclusters (RuNCs) with small size and high dispersity. The as-prepared RuNCs/Ti3C2T x catalysts exhibit excellent catalytic activity and selectivity for the hydrogenation of quinolines. The theoretical calculation confirms that there exists charge transfer between Ru and the functional groups (e.g., F and O) on Ti3C2T x , which can weaken the H adsorption and promote the desorption of hydrogenated products, contributing to the outstanding hydrogenation performance of RuNCs/Ti3C2T x catalysts. The findings pave an avenue towards improving the hydrogenation performance of quinolines over Ru-based catalysts.