Effect of the Ti content and pore size of mesoporous catalysts on CO2 photoreduction.

• Atomic-level dispersion in silica optimized the Ti utilization efficiency. • Mesoporous SiO 2 with only 3 wt% Ti is compatible with pure TiO 2 photocatalyst. • The pore size of mesoporous silica affects CO 2 photoreduction selectivity. • Findings can guide the optimization of photocatalytic efficiency for CO 2 conversion. The photocatalytic conversion of CO 2 into chemicals and fuels is a promising approach for reducing atmospheric CO 2 and addressing energy demands. This study investigates the impact of titanium (Ti) content and pore size in mesoporous silica on CO 2 photoreduction (CO 2 PR) efficiency. Ordered mesoporous silica with a large surface area and stability is used as a matrix for Ti dispersion. Two sets of photocatalysts with varying Ti contents and pore sizes are synthesized and assessed for their microstructures, photoelectric properties, and CO 2 PR efficiency in both solid–gas and liquid–gas modes. The results reveal that photocatalysts with only 3.0 wt% Ti perform comparably to commercial TiO 2 (P25) and can be recycled and reused. Moreover, an enhancement in photocatalytic activity with increasing pore sizes of the photocatalysts is observed. Notably, a photocatalyst with 3.0 wt% Ti and about 8 nm pore size significantly outperforms P25, producing much higher CH 4 , CO, and CH 3 OH yields. These findings are crucial for optimizing photocatalyst efficiency and are applicable across various compositions. [ABSTRACT FROM AUTHOR]