Photo-assisted thermal catalytic CO reduction over Ru-TiO catalysts.

Photothermal catalysis is a promising technology to convert CO into high value-added products. Here, we show that loading Ru NPs on TiO achieved a remarkable photothermal synergistic effect and the Ru-TiO demonstrated a high efficiency for the photothermal conversion of low CO concentration to CH at the gas-solid interface. The photothermal activity of the Ru-TiO (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 to Ru particles, beneficial to CO reduction, while external heating showed no influence on the charge separation of the Ru-TiO. Hence, the photothermal synergy is not a heat-assisted photocatalytic process, but a photo-assisted thermal catalytic process. We finally demonstrated that the CO was firstly converted to CO, and the CO was further hydrogenated to CH. 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. This work contributes to further understanding of the mechanism of photothermal catalytic CO reduction.