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 catalytic 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 multifunctional material.