Solar-driven gas phase photocatalytic CO2 methanation by multimetallic UiO-66 solids decorated with RuOx nanoparticles

As there is an urgent need to produce solar fuels from CO2, we here report on the development of a series of multimetallic UiO-66(Zr/Ce/Ti) solids-supported RuOx nanoparticles as photocatalysts for selective gas phase CO2 methanation by H2 under simulated sunlight irradiation. The trimetallic UiO-66(Zr/Ce/Ti) based-photocatalyst exhibits higher activity (1,900 μmol g−1 of CH4 after 22 h) than analogous mono- [UiO-66(Zr) or UiO-66(Ce)] and bimetallic [UiO-66(Zr/Ce) or UiO-66(Zr/Ti)] derivatives, as well as higher than previous reports on metal–organic frameworks (MOFs). The experimental evidence on the observed order of photocatalytic activity and insights into the occurrence of a dual photochemical and photothermal mechanism for the most active trimetallic sample were obtained by means of spectroscopic techniques including fluorescence and laser flash photolysis, photoelectrochemical and additional photocatalytic measurements. This study exemplifies the benefits of developing multimetallic MOF-supported metal nanoparticles to achieve high photocatalytic activity for solar-driven gas phase CO2 conversion.