Tm, Yb co-doped urchin-like CsxWO3 nanoclusters with dual functional properties: Transparent heat insulation performance and enhanced photocatalysis

In order to obtain ideal CsxWO3 powders that combine transparent thermal insulation and outstanding photocatalytic degradation of pollutants, Tm3+, Yb3+ co-doped CsxWO3 ((Tm, Yb)-CsxWO3) urchin-like nanoclusters were synthesized in situ by facile solvothermal reaction and subsequent heat treatment. The effects of Tm, Yb co-doping on the crystal structure, adsorption/photocatalysis, visible transmittance and near-infrared (NIR) absorption of CsxWO3 particles were investigated. The results indicate that the as-prepared (Tm, Yb)-CsxWO3 samples exhibit significantly improved photocatalytic activity while maintaining excellent visible transmittance and NIR shielding properties. In particular, sample 2T-10YC with 2 mol% Tm/10 mol% Yb co-doped CsxWO3 exhibited highest photocatalytic activity with the photocatalytic degradation efficiency of Rhodamine B attaining to 69.86%, and its films prepared from dispersion of powder samples exhibit high transparent heat shielding performance with visible transmittance 71.4% and NIR shielding rate 90.8%, respectively. The enhanced photocatalytic activity of the sample can be ascribed to the lattice distortion and decrease of band gap caused by Tm, Yb co-doping, and the increased light utilization due to the formation of impurity energy level and multiple light reflection caused by hierarchical structure can also enhance the photocatalytic activity. Moreover, the introduction of Tm and Yb elements can also refine the CsxWO3 grains, which is conducive to improving the visible transmittance. Thus, the as-prepared bifunctional (Tm, Yb)-CsxWO3 particles will have potential application prospects in the field of energy-saving and environmental purification.