Elucidating structure and function of Ni/La-doped-ceria catalysts for CO2 reduction by the reverse water gas shift reaction

Reducing and/or utilizing CO2 in the atmosphere is mandatory to decrease its negative effects as greenhouse gas. The reverse water gas shift reaction (rWGS) is one of the most promising routes for CO2 valorization. Here, we show that Ni/La-doped ceria catalysts, prepared by the solution combustion synthesis method, has an excellent catalytic performance per unit mass of catalyst. Structure-activity correlations obtained using a combination of different techniques such as X-ray and neutron diffraction, Raman spectroscopy, in-situ NAP-XPS, Electron Microscopy, and catalytic testing, point out to optimum values for the Ni loading and the La proportion. Density functional theory calculations of the elementary steps of the reaction on model Ni/ceria catalysts aid toward the microscopic understanding of the active sites nature. Metallic Ni activates H2 dissociation and a certain La doping maximizes Ce3+ sites, which supplies greater available oxygen to form H2O. These findings are essential for the rational design of highly efficient and selective rWGS catalysts.