Transparent and Bendable Silica Aerogels Integrated with CsxWO3 Films for Photothermal Temperature Self-Regulating Systems

Constructing a solar-powered photothermal system that can self-regulate temperature without requiring extra energy input is significant for energy saving, but how to achieve zero-energy building remains challenging. Here, a photothermal system that integrates sunlight harvesting, photothermal conversion (PTC), and heat storage was constructed. Well-developed nanoscale pore silica aerogels with high transparency (visible-light transmittance 69.3%, near-infrared transmittance 86.9%), bending resistance (bending angle >30°), and low thermal conductivity were prepared by the interpenetration of C and Si molecular networks using vinyltrimethoxysilane as the silica source, which was used as a window material for the temperature self-regulating system to block heat loss and allow sunlight transmission. Simultaneously, the prepared CsxWO3 (CWO) film with PTC could convert sunlight into heat. Also, PEG 2000 is introduced into the system with a suitable phase transition temperature to further realize temperature self-regulation within a certain range. The outdoor simulation test results showed that the system could heat water to 69.8 °C using sunlight in cold weather around 0 °C, which was 67.6 °C higher than the ambient temperature and can stay above 18 °C for about 20 h, and even in cloudy weather, it could reach 58.2 °C. The highly transparent silica aerogel is given the ability to resist bending, which opens up more application prospects for silica aerogels, and the constructed self-regulating temperature system without additional energy input contributes to the development of the zero-energy building.