Effects of SiO2-based scaffolds in TiO2 photocatalyzed CO2 reduction

CO2 photoreduction has claimed as appealing process to upgrade a waste gas into valuable fuels or chemicals. Titanium dioxide (TiO2) is one of the most popular material used as catalyst for this reaction, having however a poor activity. The utilization of transparent, insulating and highly porous scaffolds to support a photoactive phase has been reported as one of the possible strategies to improve the performances of this material. In this work, two silica-based materials with different porosity type and level, were involved as support for the TiO2 and assessed in the gas-phase CO2 photoreduction with H2O. The morphological, structural and surface properties were then evaluated by means of different characterization techniques, aiming to correlate them with the cat-alytic activity and selectivity. The TiO2-SiO2 composites revealed a comparable activity compared to pure TiO2, despite the low fraction of photoactive phase due to improved light harvesting and reagents adsorption on the composites. The CO2 capture/photoconverting ability was evaluated, to explore the potentiality as multifunc-tional material.

Automated summary

This study investigated two silica-based materials with different porosity levels as supports for titanium dioxide in gas-phase CO2 photoreduction. The TiO2-SiO2 composites demonstrated comparable catalytic activity to pure TiO2, despite a low fraction of photoactive phase, due to improved light harvesting and reagents adsorption.