Abstract
Buildings consume 40% of global energy, over half of which is used for cooling and heating. Tungsten bronze (M(x)WO(3)) holds promise for smart windows due to its ability to block near-infrared (NIR) heat radiation while maintaining visible light transmittance. However, conventional high-temperature synthesis is energy intensive. Here, we develop a low-temperature hydrothermal method (170 °C) to prepare Li and Cs co-doped tungsten oxide using WCl(6), LiF, and CsOH·H(2)O as precursors, with acetic acid as a crystallographic modulator. The material exhibits a hexagonal structure (P6(3)/mcm) and Li(+)-induced lattice expansion (0.34 nm spacing). Combined XPS and ICP-OES analyses confirm the chemical composition as Cs(0.31)Li(0.09)WO(3) and reveal a positive correlation between the W(5+) content (15.76%) and oxygen vacancy concentration, which is identified as the key factor enhancing the NIR absorption. The material demonstrates excellent visible light transmission and NIR shielding properties. Our work provides a more energy-efficient and sustainable pathway for the production of smart window materials.