Transparent and Bendable Silica Aerogels Integrated with Cs_xWO₃ 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 Cs x WO 3 (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.