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.

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.

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) (O^2-, ·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.