Origin of synergistic effects in bicomponent cobalt oxide-platinum catalysts for selective hydrogenation reaction

Abstract 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 x Pt/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 x Pt/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.