Unravelling the synergy of platinum-oxygen vacancy in CoO_x for modulating hydrogenation performance

Constructing high-efficiency catalysts with high activity and selectivity is the long-term pursuit in heterogeneous catalysis field. Metal–oxygen vacancy (Ov) synergy provides a promising route to realizing the goal. In this study, the Pt/CoO_x catalysts with Pt–Ov dual sites are designed by atomic layer deposition (ALD) for selective hydrogenation of cinnamaldehyde, and the Ov property, Pt size and the spatial relationship of Pt and CoO_x can be well modulated. Experimental and theoretical investigations indicate that the substrate and hydrogen can be activated on Ov and Pt nanoparticles, respectively. The Ov introduced by ALD not only preferentially activates C[dbnd]O bond of CALD to achieve high selectivity to CALA, but also enhances the ability to dissociate hydrogen on Pt nanoparticles through Pt-Ov electron transfer. Importantly, the optimized Pt40/CoO_x-Ov catalysts with suitable Ov coordination and Pt sizes (2.5 nm) show lower adsorption energy for reactant molecules, obtaining significantly enhanced activity with a turnover frequency value of 202.5 mol_CALD·mol_Pt ^-1·min⁻¹ and obviously improved selectivity of desired products (93 %). This work offers a fundamental understanding of Pt–Ov synergy toward hydrogenation of unsaturated compounds.