The Effect of the Pore Size of TiO2 Aerogel on the Photocatalytic Decomposition of Formaldehyde

TiO2 aerogels have been employed for the degradation of formaldehyde (HCHO) via the photocatalytic generation of reactive oxygen species (ROS) (O2−, ·OH), and its pore size plays a crucial role in affecting the decomposition efficiency. However, there remains a lack of a comprehensive understanding regarding the internal mechanisms underlying the influence of pore size on HCHO decomposition. In this study, we prepared TiO2 aerogels by the sol–gel method, and added polyvinyl alcohol (PVA) to introduce flexible molecular chains for pore size regulation, and obtained anatase crystals after a heat treatment at 800 °C. The photocatalytic decomposition mechanism of HCHO was researched using TiO2 aerogels with varying pore sizes as catalysts. The results indicated that the pore size of TiO2 aerogels was one of the important factors for HCHO decomposition. We validated that the efficiency of HCHO decomposition was related to the oxygen pressure in the pores of the TiO2 aerogel, and the oxygen pressure was inversely proportional to the pore size, then the pore size of the TiO2 aerogel and the decomposition efficiency of HCHO were linked through the oxygen pressure. Finally, the optimal pore size of the TiO2 aerogel for the photocatalytic HCHO decomposition was 2 nm–10 nm. The present study aims to establish the relationship and influence of the pore size of TiO2 aerogels on the performance of photocatalytic decomposition and promoting further advancements in porous nanomaterials for catalysis.