Effects of oxide platforms on the dynamics and reduction characteristics of hydrogen spillover.

The characteristics of hydrogen spillover on various metal oxides, involving the concurrent diffusion of protons (H) and electrons (e), were systematically studied by combining analytical techniques with kinetic analyses. H-temperature programmed reduction and X-ray absorption fine structure data showed that hydrogen spillover from Pt onto TiO and WO greatly decreased the temperatures at which Zn ions deposited on these remote metal oxides were reduced. In contrast, hydrogen spillover on MgO and CeO did not significantly affect the reduction of remote Zn. Mechanisms explaining the effects of spilled hydrogen on reduction for each oxide substrate were proposed based on the dynamic behaviors of H and e as ascertained by means of spectroscopic characterizations and kinetic analyses. The results of this work indicate that e diffusion rather than H diffusion promotes the reduction of deposited metal ions and that interparticle hydrogen spillover can be facilitated over TiO and WO as a consequence of the interfacial diffusion of H and e pairs. These findings provide an improved understanding of the hydrogen spillover phenomenon.