CO2 methanation over Ni nanoparticles inversely loaded with CeO2 and Cr2O3: Catalytic functions of metal oxide/Ni interfaces

Interfaces between active metal and metal oxide in a heterogenous catalyst often play an important role in catalysis. In this work, we intentionally synthesized a series of inverse CeO2-Cr2O3/Ni model catalysts with the formation of controlled CeO2-Ni and Cr2O3-Ni interfacial structures and investigated the roles of the oxide-metal interfaces in CO2 methanation performance through excluding the normal support effect. Experimental and DFT calculation results reveal that the formate pathway tends to occur on the catalyst with only CeO2-Ni interfaces. The Cr2O3-Ni interface formed after introducing Cr oxide alters the nearby CeO2-Ni interface by electron transfer through Ni, which brings an additional reaction pathway (CO pathway) on CeO2-Cr2O3/Ni. Furthermore, it shows a relatively lower CO2 absorption energy and activation energy barrier for CO2 dissociation to CO at the Cr2O3-Ni interface, favorable for CO2 activation and further hydrogenation, thus leading to excellent lowtemperature activity.