The synergistic nature of bicomponent catalysts remains a challenging issue, due to the difficulty in constructing well-defined catalytic systems. Here we study the origin of synergistic effects in CoO x-Pt catalysts for selective hydrogenation by designing a series of closely contacted CoO xPt/TiO 2 and spatially separated CoO x/TiO 2/Pt catalysts by atomic layer deposition (ALD). For CoO x/TiO 2/Pt, CoO x and platinum are separated by the walls of titania nanotubes, and the CoO x-Pt intimacy can be precisely tuned. Like CoO xPt/TiO 2, the CoO x/TiO 2/Pt shows higher selectivity to cinnamyl alcohol than monometallic TiO 2/Pt, indicating that the CoO x-Pt nanoscale intimacy almost has no influence on the selectivity. The enhanced selectivity is ascribed to the increased oxygen vacancy resulting from the promoted hydrogen spillover. Moreover, platinum-oxygen vacancy interfacial sites are identified as the active sites by selectively covering CoO x or platinum by ALD. Our study provides a guide for the understanding of synergistic nature in bicomponent and bifunctional catalysts.
The development of catalysts with high activity and selectivity for hydrogenation remains a challenge. Here the authors report cobalt oxide-platinum catalysts with increased oxygen vacancy resulting from the promoted hydrogen spillover with platinum-oxygen vacancies as active sites.