Sb-doped SnO2 (ATO) hollow submicron spheres for solar heat insulation coating

Abstract Antimony doped Tin Oxide (ATO) hollow submicron spheres were synthesized with a carbon ball template using the hydrothermal method, and compared to commercial nano-ATOs that differed in particle size. To study the thermal insulation performance and the mechanism of different ATOs, their morphology, crystalline structure and microstructure were examined using XRD, SEM and HRTEM. Meanwhile, the optical and thermal characteristics of the different ATOs, including absorption, reflectance, thermal conductivity, infrared emissivity (8–14 μm), and specific heat capacity, were also measured. Silicone acrylic emulsion coatings containing different dosages of ATO were then prepared, and their UV–Vis–NIR transmittance and solar heat shielding performances were tested. ATO hollow submicron spheres showed a thermal insulation performance comparable to that of nano-ATO, but their main respective thermal insulation mechanism was different. ATO hollow submicron spheres primarily relied on better particle dispersion, lower thermal conductivity, higher specific heat capacity and higher infrared emissivity. The 50 nm ATO absorbed the least solar heat but reflected the most light, while 100 nm ATO showed the opposite behavior. Both nano-ATOs had better transmittance in the visible light range but relatively low transmittance in the ultraviolet and infrared range. The results of this study indicate that ATO hollow submicron spheres are promising materials equivalent to nano-spheres that can be applied as a coating for energy conservation.