Suppressing Metal-Support Interaction Enhances Photothermal\nCO<sub>2</sub> Methanation on the Ru/CeO<sub>2</sub> Catalysts

Metal-support\ninteractions can significantly affect the catalytic\nperformance of heterogeneous catalysts and have been studied extensively\nin thermal catalysis and electrocatalysis. However, the role of strong\nmetal-support interactions (SMSIs) in regulating photoinduced electron\ntransfer has been rarely investigated in photocatalysis. In this study,\nwe have prepared two model catalysts using the impregnation methodone\nwith SMSI effect (Ru/CeO<sub>2</sub>) and the other with suppressed\nSMSI effect (Ru/CeO<sub>2</sub>–H<sub>2</sub>)and tested\nthem for photothermal CO<sub>2</sub> methanation. The methane production\nrate of Ru/CeO<sub>2</sub>–H<sub>2</sub> (275.1 mmol/g<sub>Ru</sub>/h) was more than twice that of Ru/CeO<sub>2</sub> (111.2\nmmol/g<sub>Ru</sub>/h) at 200 °C under light irradiation. Various\ncharacterizations and theoretical calculations suggest that hot electrons,\ngenerated by local surface plasma, transferred to the Ru/CeO<sub>2</sub>–H<sub>2</sub> from the dispersed Ru sites, filling the oxygen\nvacancies in Ru/CeO<sub>2</sub>–H<sub>2</sub>, where the adsorption\nand activation of CO<sub>2</sub> was enhanced under light irradiation.\nAlso, it is evident that the electron-deficient Ru sites speed up\nthe decomposition of H<sub>2</sub>. The <i>in situ</i> diffuse\nreflectance infrared Fourier transform spectroscopy (DRIFTS) studies\nshowed that CO<sub>2</sub> methanation on Ru/CeO<sub>2</sub>–H<sub>2</sub> and Ru/CeO<sub>2</sub> chiefly followed the formate-intermediated\npathway, although the CO-intermediated pathway was also present. This\nstudy offers a technique to enhance photothermal CO<sub>2</sub> methanation\nby controlling the interaction between the metal and the support.