Theoretical Study of the Impact of Pore Size in TiO₂ Aerogels on Photocatalytic Formaldehyde Decomposition

Abstract

Formaldehyde (HCHO), an indoor volatile organic compound, is seriously harmful to human health. Therefore, green and effective decomposition of HCHO is essential. TiO2 has been employed for the degradation of HCHO via photocatalytic generation of reactive oxygen species (ROS) (O2-, ·OH), yet the low specific surface area of crystalline TiO2 depressed the catalytic performance. Herein, we prepared TiO2 aerogels with high specific surface area and high porosity by sol-gel method, and added PVA to introduce flexible molecular chains for pore size regulation. The photocatalytic performance test verifies that the pore size of TiO2 aerogel is one of the important factors for HCHO decomposition. Notably, through the establishment of theoretical model and calculation, we validated that the efficiency of HCHO decomposition is related to the oxygen pressure in the pores of TiO2 aerogel, and the oxygen pressure is inversely proportional to the pore size. Accordingly, the optimal pore size of TiO2 aerogel for the photocatalytic HCHO decomposition is 2 nm~10 nm. This study provides a theoretical idea for TiO2 aerogels in the decomposition reaction of HCHO, which is expected to inspire more breakthroughs in the study of TiO2 aerogels for green chemistry.