Photo-Initiated Reduction of CO2 by H2 on Silica Surface.

Abstract

The reduction of CO2 is a promising route to produce valuable chemicals or fuels and create C-neutral resource cycles. Many different approaches to CO2 reduction have been investigated, but the ability of vacuum UV (VUV) irradiation to cleave C-O bonds has remained largely unexplored for use in processes that convert CO2 into useful products. Compared with other photo-driven CO2 conversion processes, VUV-initiated CO2 reduction can achieve much greater conversion under common photochemical reaction conditions when H2 and non-reducible oxides are present. Infrared spectroscopy provides evidence for a chain reaction initiated by VUV-induced CO2 splitting, which is enhanced in the presence of H2 and silica. When the reaction is carried out in the presence of silica or alumina surfaces, CO yields are increased and CH4 is formed as the only other detected product. CH4 production is not promoted by traditional photocatalysts such as TiO2 under these conditions. Assuming improvements in lamp and reactor efficiencies with scale up, or coupling with other available CO/CO2 hydrogenation techniques, these results reveal a potential, simple strategy by which CO2 could be valorized.