Photo-assisted thermal catalytic CO2 reduction over Ru-TiO2 catalysts

Photothermal catalysis is a promising technology to convert CO 2 into high value-added products. Here, we show that loading Ru NPs on TiO 2 achieved a remarkable photothermal synergistic effect and the Ru-TiO 2 demonstrated a high efficiency for the photothermal conversion of low CO 2 concentration to CH 4 at the gas-solid interface. The photothermal activity of the Ru-TiO 2 (217.9 µmol/(g·h)) was nearly 6 times higher than pure thermal activity (38.08 µmol/(g·h)), and nearly 20 times than the photocatalytic activity (10.9 µmol/(g·h)). We revealed that the light excitation could drive the generated electrons from TiO 2 to Ru particles, beneficial to CO 2 reduction, while external heating showed no influence on the charge separation of the Ru-TiO 2 . Hence, the photothermal synergy is not a heat-assisted photocatalytic process, but a photo-assisted thermal catalytic process. We finally demonstrated that the CO 2 was firstly converted to CO, and the CO was further hydrogenated to CH 4 . The introduction of light could promote the activation of intermediate CO species at the Ru-Ti interface sites, thus greatly accelerating CO hydrogenation to CH 4 . This work contributes to further understanding of the mechanism of photothermal catalytic CO 2 reduction.