Titanium-Perovskite-Supported RuO2 Nanoparticles for Photocatalytic CO2 Methanation

This manuscript reports the photothermal activity for CO2 methanation of RuO2 nanoparticles supported on strontium titanate (STO) operating at 150°C under simulated sunlight irradiation. The RuO2/STO sample having the optimal performance exhibits under ultraviolet-visible (UV-vis) irradiation with a power of 108 mW/cm2 at 150°C a CH4 production rate of 14.6 mmol CH4 h−1 g−1. The photoresponse of the material is mainly due to UV photons, although RuO2/STO still retains about 50% efficiency under visible light irradiation (>400 nm). Mechanistic studies are compatible with a photothermal process with minor contribution of photocatalytic electron-hole pair charge separation. The photocatalyst is efficient enough to also operate under continuous flow conditions, achieving with a contact time of 3 s at 150°C under about 1 sun irradiation a steady-state CH4 production rate of 30 μmol h−1 for an 8-h-long experiment. This value ranks the material among the most efficient methanation photocatalysts.