Unraveling Oxygen Vacancy-Driven Catalytic Hydrogen Evolution Activity and Stability over Atomic-Layer-Deposited Platinum Cluster Catalysts

Abstract

Utilizing metal-oxygen vacancy (Ov) synergy to modulate catalytic performance is an efficient route in heterogeneous catalysis. While the quantitative tuning toward the Ov concentration and corresponding establishment of Ov concentration-performance relationship have been rarely reported. Herein reducible MoO3 nanorods supported Pt 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 (Ptn) deposited on MoO3 can promote Ov generation through the hydrogen spillover effect, which also serve as the anchoring sites of Pt clusters inhibiting their agglomeration. We achieve the independent modulation toward Ov concentration of MoO3-x while preserving nearly unchanged Pt particle size, and the volcano-shape relationship between Ov concentration and catalytic activity is definitely established. The optimized Ptn/MoO3-x-150R cluster catalysts with a mean particle size of 1.41 nm and suitable Ov concentration (5.58×10 13 spin•g -1 ) exhibit optimized H2 evolution activity and durability for hydrolytic dehydrogenation reaction of ammonia borane (AB), whose activity is 5.7-fold higher than that of as-prepared Ptn/MoO3 catalysts. Multiple characterizations and theoretical calculations results indicate that electron-rich Pt cluster is responsible for the activation of AB and Ov affords the adsorption site for H2O molecule, and the synergy of Ptn-Ov dual sites facilitates the adsorption-dissociation of H2O molecules being the rate-determining step. This study would provide deep insights for the rational design of dual-site catalysts by utilizing the synergy between metal cluster and oxygen vacancy with suitable concentration.