Fabrication of thermal insulation sodium alginate/SiO2 composite aerogel with superior radiative cooling function for firefighting clothing

PurposeThis study aims to evaluate the thermal performance of sodium alginate (SA) aerogel attached to nano SiO2and its radiative cooling effect on firefighting clothing without environmental pollution.Design/methodology/approachSA/SiO2aerogel with refractory heat insulation and enhanced radiative cooling performance was fabricated by freeze-drying method, which can be used in firefighting clothing. The microstructure, chemical composition, thermal stability, and thermal emissivity were analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analyzer and infrared emissivity measurement instrument. The radiative cooling effect of aerogel was studied using thermal infrared imager and thermocouple.FindingsWhen the addition of SiO2is 25% of SA, the prepared aerogel has excellent heat insulation and a high radiative cooling effect. Under a clear sky, the temperature of SA/SiO2aerogel is 9.4°C lower than that of pure SA aerogel and 22.1°C lower than that of the simulated environment. In addition, aerogel has more exceptional heat insulation effect than other common fabrics in the heat insulation performance test.Research limitations/implicationsSA/SiO2aerogel has passive radiative cooling function, which can efficaciously economize global energy, and it is paramount to environment-friendly cooling.Practical implicationsThis method could pave the way for high-performance cooling materials designed for firefighting clothing to keep maintain the wearing comfort of firefighters.Originality/valueSA/SiO2aerogel used in firefighting clothing can release heat to the low-temperature outer space in the form of thermal radiation to achieve its own cooling purpose, without additional energy supply.Graphical abstract