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

Abstract

TiO₂–Cs_xWO₃ 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–Cs_xWO₃ composite nanoparticles with a particle size of less than 30 nm. With increasing Ti/W molar ratio, the specific surface area of the TiO₂–Cs_xWO₃ particles increased, and the crystalline phase was transformed from Cs_0.3WO₃ to Cs_0.32WO₃ and gradually to Cs_0.2WO₃ with a small amount of emerging Ti₃O₅ crystals. In comparison with the pure Cs_xWO₃ and Cs_xWO₃@TiO₂ composite particles with TiO₂ coated on Cs_xWO₃, the as-synthesized TiO₂–Cs_xWO₃ 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 Cs_xWO₃ greatly improved the adsorption/photocatalytic performance. When the Ti/W ratio was 0.4, TiO₂–Cs_xWO₃ 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.