Overturning CO2 Hydrogenation Selectivity by Tailoring the Local Electron Density of Ru/CeO2 Catalysts

Flexible tuning of the CO2 hydrogenation selectivity through properly designed catalysts to obtain desired high-added-value products is a promising strategy for addressing environmental and energy issues but also a huge challenge. Herein, the CO2 hydrogenation selectivity over the commonly used Ru/CeO2 methanation catalysts was facilely overturned from ∼99% CH4 to 100% CO by tailoring the local electron density of Ru through electronic interaction induced by electron acceptors (Bi, In, Sn, etc.). Systematically, in situ spectroscopic characterizations and DFT calculations reveal that owing to the electron-withdrawing role of the electron acceptor, Ru sites lose more charges than the unmodified catalyst, which weakens the binding strength of carbonyl to Ru sites and further induces the imbalance reaction energy barrier for carbonyl and formate intermediates. Thus, the original parallel reaction processes involving CH4 generation (carbonyl route and formate route) are transformed into the preferential desorption of CO, finally acquiring opposite selectivity. Importantly, such an electronic interaction is general for overturning product selectivity and can be extended to other Ru catalysts and Ni catalysts. This discovery may offer a promising way to develop CO2 hydrogenation catalysts with controllable product selectivity.