Energy-saving low-E with dual IR-reflective and UV-protective TiO2-ZnO- SiO2 coated glass

This study reports the design and evaluation of functionally graded sol–gel coatings based on TiO₂, ZnO, and SiO₂ nanoparticles for low-emissivity (Low-E) glazing. By engineering the gradient structure and layer sequence, the coatings combine high infrared (IR) reflectivity for thermal insulation with strong ultraviolet (UV) blocking, while maintaining excellent visible light transmittance. X-ray diffraction revealed nanocrystalline anatase TiO₂ (33.7 nm), hexagonal ZnO (82 nm), and amorphous SiO₂, confirming the tailored nanostructures. Optical analysis demonstrated >80% visible transmittance, >60% UV blocking, high IR reflectance, and emissivity as low as ~0.38, indicating significant energy-saving potential. The synergistic performance arises from TiO₂’s UV absorption, ZnO’s IR reflection, and SiO₂’s protective and anti-reflective roles, surpassing conventional single-layer or metallic coatings. These results establish sol–gel-derived TiO₂–ZnO–SiO₂ coatings as a cost-effective, durable, and sustainable alternative for energy-efficient glazing, with promising applications in smart windows and climate-responsive building envelopes.