| Sumario: | CO reduction by sunlight under mild reaction conditions is a research area of increasing interest expected to favor decarbonization and produce fuels and chemicals in the circular economy. We hereby report on the development of a series of titanium oxide-based solids produced by calcination of MIL-125(Ti)-NH decorated with RuO nanoparticles (1 wt %) material at temperatures from 350 to 650 °C and used as photocatalysts for CO methanation under simulated sunlight irradiation (45 mW/cm) at <200 °C and 1.5 atm total pressure. The material synthesized at 350 °C produced the highest photoactivity of the series (4.73 mmol g CH at 22 h and an apparent quantum yield at 400, 500 and 750 nm of 0.76, 0.65 and 0.54 %, respectively), comparing favorably with the activities of other MOF-based materials reported so far. Insights into the material's photocatalytic performance and a study of the possible reaction pathways during CO methanation were obtained by electrochemical impedance, electron spin resonance, photoluminescence and in situ FT-IR spectroscopies together with transient photocurrent and hydrogen temperature programed desorption measurements. The study showed the possibility of using MOF-based materials as precursors to develop metal oxide photocatalysts with enhanced activities for solar-driven gaseous CO photomethanation.
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