Greatly improved heat-shielding performance of KxWO3 by trace Pt doping for energy-saving window glass applications

•Pt doping contributes to uniform growth of hexagonal KxWO3 nanorods.•Pt doping is conducive to increasing the content of reduced W (W4+ and W5+).•Trace Pt doping can greatly improve the heat shielding property of KxWO3 powders.•Trace Pt-doped KxWO3 has excellent transparency and heat insulation performance.

Pt-doped KxWO3 nanorods with excellent near-infrared shielding and heat insulation performance were prepared by solvothermal reduction method using cheap sodium tungstate as raw materials. The effects of K/W ratio and Pt doping on the microstructure, morphology and transparent heat insulation performance of KxWO3 particles were investigated. It was found that Pt doping contributed to increasing the content of W in reduced state (W5+ and W4+), promoting the uniform growth of hexagonal KxWO3 nanorods and decreasing the particle size. Compared with the undoped KxWO3 particles, Pt-doped KxWO3 samples exhibited improved near-infrared shielding and heat insulation properties. Particularly, when K/W was 0.4, the incorporation of trace Pt (0.1 mol%) greatly improved the near-infrared shielding and transparent insulation properties of KxWO3 particles, which is ascribed to its lower powder resistivity and more content of W in reduced state (W5+ and W4+). Whereas too much Pt-doping amount tended to decrease the visible light transmittance of KxWO3. The mechanism of Pt doping promoting the W5+/W4+ formation and improving the heat insulation of KxWO3 were discussed. It is suggested that the trace Pt-doped KxWO3 particles with excellent transparency and heat insulation properties are more suitable for the preparation of transparent insulation films and have broad applications in the field of energy-saving window glasses.

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