Toward solar-driven photocatalytic CO2 methanation under continuous flow operation using benchmark MIL-125(Ti)–NH2 supported ruthenium nanoparticles

Abstract

The production of solar fuels from CO2 is currently attracting increasing interest. Herein we describe the development of a benchmark metal–organic framework (MOF) photocatalyst based on MIL-125(Ti)–NH2 supported ruthenium nanoparticles for solar-driven selective photocatalytic CO2 methanation. The optimized RuOx(10 wt%; 1.48 nm)@MIL-125(Ti)–NH2 photocatalyst is exceptionally active (18.5 mmol g−1 at 22 h) and reusable (10 cycles for 220 h) in the CO2 methanation at 200 °C under batch conditions and simulated sunlight irradiation. The photocatalyst can also be employed for continuous-flow CO2 methanation under visible light irradiation at 200 °C for at least 50 h. Evidence in support of the operation of a dual photo-thermal mechanism that combines a photochemical mechanism based on e-/h+ separation and thermochemical contributions in which the energy of photons produces local heating has been obtained for the photocatalytic CO2 methanation. We are confident that this study will contribute to the development of active MOF-based photocatalysts for solar-driven CO2 methanation under continuous flow operations with industrial interest.