Enhanced generation and stabilization of oxygen vacancy on defective ceria by platinum cluster as dual-site catalysts to boost hydrogen production activity and stability

Utilizing the synergy between metal and oxygen vacancy (Ov) on reducible supports is a promising route to modulating catalytic performance. Herein, defective CeO₂ nanorods supported Pt dual-site catalysts with high-dispersion cluster and specific Ov concentration were finely constructed by combining atomic layer deposition and the designed hydrogen activation strategy. The Pt clusters deposited on CeO₂ not only can promote more Ov generation through the hydrogen spillover effect, but also can stabilize the generated Ov via the stored active hydrogen. Meanwhile, the Ov also serves as the anchoring sites of Pt clusters inhibiting their agglomeration. We independently modulate the Ov concentration of ceria while preserving nearly unchanged cluster size, which enables the quantitative analysis of the effect of individual Ov concentration on catalytic activity and stability. The Ov concentration-activity relationship is established presenting a volcano-shape curve, and the optimized Pt_n/CeO_2-x-350R catalysts with a mean particle size of 1.1 nm and suitable Ov concentration (3.55 ×10¹³ spins g⁻¹) exhibit excellent H₂ production activity and much-enhanced durability for hydrolytic dehydrogenation reaction of ammonia borane (AB), whose activity is 4-fold higher than that of as-prepared Pt_n/CeO₂ cluster catalysts. Experimental and theoretical calculation results indicate that electron-rich Pt cluster is responsible for the barrierless activation and dehydrogenation of AB, while Ov affords the adsorption site for H₂O molecules and forms synergistical dual sites promoting the adsorption−dissociation of H₂O molecules being the rate-determining step.