Solar‐Assisted CO₂ Methanation via Photocatalytic Sabatier Reaction by Calcined Titanium‐based Organic Framework Supported RuO_x Nanoparticles

Abstract

CO2 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)‐NH2 decorated with RuOx nanoparticles (1 wt%) material at temperatures from 350 to 650 ºC and used as photocatalysts for CO2 methanation under simulated sunlight irradiation (45 mW/cm2) at < 200 ºC and 1.5 atm total pressure. The material synthesized at 350 ºC produced the highest photoactivity of the series (4.73 mmol g‐1 CH4 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 CO2 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 of metal oxide photocatalysts with enhanced activities for solar‐driven gaseous CO2 photomethanation.