Microwave-Assisted Solvothermal Synthesis of Cesium Tungsten Bronze Nanoparticles

Cesium tungsten bronzes (Cs_xWO₃), as functional materials with excellent near-infrared shielding properties, demonstrate significant potential for applications in smart windows. However, traditional synthesis methods, such as solid-state reactions and solvothermal/hydrothermal approaches, typically require harsh conditions, including high temperatures (above 200 °C), high pressure, inert atmospheres, or prolonged reaction times. In this study, we propose an optimized microwave-assisted solvothermal synthesis strategy that significantly reduces the severity of reaction conditions through precise parameter control. When benzyl alcohol was employed as the solvent, Cs_xWO₃ nanoparticles could be rapidly synthesized within a relatively short duration of 15 min at 180 °C, or alternatively obtained through 2 h at a low temperature of 140 °C. However, when anhydrous ethanol, which is cost-effective and environmentally friendly, was substituted for benzyl alcohol, successful synthesis was also achieved at 140 °C in 2 h. This method overcomes the limitations of traditional high-pressure reaction systems, achieving efficient crystallization under low-temperature and ambient-pressure conditions while eliminating safety hazards and significantly improving energy efficiency. The resulting materials retain excellent near-infrared shielding performance and visible-light transparency, providing an innovative solution for the safe, rapid, and controllable synthesis of functional nanomaterials.