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

Abstract

The photocatalytic conversion of CO2 into chemicals and fuels is a promising approach for reducing atmospheric CO2 and addressing energy demands. This study investigates the impact of titanium (Ti) content and pore size in mesoporous silica on CO2 photoreduction (CO2PR) 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 CO2PR efficiency in both solid–gas and liquid–gas modes. The results reveal that photocatalysts with only 3.0 wt% Ti perform comparably to commercial TiO2 (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 CH4, CO, and CH3OH yields. These findings are crucial for optimizing photocatalyst efficiency and are applicable across various compositions.