A Novel Synergetic Effect Between Ru and CeO2 Nanoparticles Leads to Highly Efficient Photothermocatalytic CO2 Reduction by CH4 with Excellent Coking Resistance

Abstract

Highly efficient photothermocatalytic CO2 reduction by CH4 (CRM) on Ru/CeO2 is realized by merely using focused UV–vis–IR irradiation. It shows very high production rates of H2 and CO (57.37 and 65.79 mmol min−1 g−1), and a large light‐to‐fuel efficiency (30.6%), much higher than those of Ru/Al2O3. It also shows good catalytic durability and excellent coking resistance with an extremely low coke formation rate (rC), 30.6 times lower than that of Ru/Al2O3. This is attributed to a synergetic effect between Ru and CeO2 nanoparticles. The formation of a Ru/CeO2 interface promotes CH4 dissociation on Ru nanoparticles. The produced carbon species is not only oxidized by the oxygen produced by CO2 dissociation on Ru nanoparticles like Ru/Al2O3, but also by the active oxygen of CeO2. CO2 molecules strongly adsorb on the resultant oxygen vacancies of CeO2, forming a CO2 molecule fence around Ru nanoparticles, accelerate the oxidation of carbon species, thus improving catalytic activity and tremendously reducing rC. The photothermocatalytic CRM on Ru/CeO2 follows a light‐driven thermocatalysis mechanism. A novel photoactivation is found to enhance the catalytic activity due to both CH4 dissociation and the oxidation of carbon species being promoted upon light irradiation.