In situ synthesis of bifunctional TiO 2 –Cs x WO 3 composite particles with transparent heat shielding and photocatalytic activity

TiO 2 –Cs x WO 3 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 TiO 2 –Cs x WO 3 composite nanoparticles with a particle size of less than 30 nm. With increasing Ti/W molar ratio, the specific surface area of the TiO 2 –Cs x WO 3 particles increased, and the crystalline phase was transformed from Cs 0.3 WO 3 to Cs 0.32 WO 3 and gradually to Cs 0.2 WO 3 with a small amount of emerging Ti 3 O 5 crystals. In comparison with the pure Cs x WO 3 and Cs x WO 3 @TiO 2 composite particles with TiO 2 coated on Cs x WO 3 , the as-synthesized TiO 2 –Cs x WO 3 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 TiO 2 and Cs x WO 3 greatly improved the adsorption/photocatalytic performance. When the Ti/W ratio was 0.4, TiO 2 –Cs x WO 3 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.