In situ synthesis of bifunctional TiO2-CsxWO3 composite particles with transparent heat shielding and photocatalytic activity

TiO2-CsxWO3 composite particles with mesoporous structure were synthesized in situ via a template-free solvothermal method followed by heat treatment under a hydrogen atmosphere. The effects of the Ti/W molar ratio on the microstructure, transparent thermal insulation, and adsorption/photocatalytic properties of the composite particles were investigated. The introduction of a small amount of n-butyl titanate in the solvothermal reaction solution could induce the formation of mesoporous TiO2-CsxWO3 composite nanoparticles with a particle size of less than 30 nm. With increasing Ti/W molar ratio, the specific surface area of the TiO2-CsxWO3 particles increased, and the crystalline phase was transformed from Cs0.3WO3 to Cs0.32WO3 and gradually to Cs0.2WO3 with a small amount of emerging Ti3O5 crystals. In comparison with the pure CsxWO3 and CsxWO3@TiO2 composite particles with TiO2 coated on CsxWO3, the as-synthesized TiO2-CsxWO3 composite particles in situ showed excellent adsorption/photocatalytic properties for rhodamine B. The mesoporous structure of the composite particles and the good synergistic effect between TiO2 and CsxWO3 greatly improved the adsorption/photocatalytic performance. When the Ti/W ratio was 0.4, TiO2-CsxWO3 particles had the highest adsorption/photocatalytic degradation efficiency for rhodamine B and excellent visible light transmission and near-infrared shielding properties. The results of this work are important for the research and development of nanoparticles with transparent thermal insulation, self-cleaning, and environmental protection functions to alleviate the current building energy consumption and pollutant emissions.