Tuning Lewis acid/base on the TiO2-supported Pd-CoOx interfaces to control the CO2 selective hydrogenation

A highly attractive aim is to turn CO2 into useful chemicals selectively and efficiently, but it still retains great challenging to understand the relations between catalytic performances and interface properties. Here, we report an alternative solution to relate the catalytic activity with the strengths of Lewis acids and bases on the Pd-CoOx interfaces. CoO∙TiO2/TiO2 and CoOx/TiO2 possess the wide spectrum of Lewis acid/base centres, and give the low selectivity and conversion. The introduction of Pd can focus them on the intrinsic centres, and makes Pd-CoO∙TiO2/TiO2 and Pd-CoOx/TiO2 represent the ideal catalysis. With temperature-programmed desorptions of CO2, CO and NH3, it is evidenced that the catalytic hydrogenations of CO2 to CO, CH4 and CH3OH depend on the cooperation of the Lewis acidic/alkaline centres on the interfaces. The studies provide guidelines for rational design and synthesis of heterogeneous catalysts including but not limited to CO2 hydrogenation.