Fabrication of photo-absorption enhanced black TiO2–SiO2 by flame spraying

Photo-absorption enhanced black TiO2–SiO2 microspheres were prepared by flame spraying synthesis. The phase composition, microstructure, infrared absorption, and emission property of the synthesized samples were investigated. Compared with the rutile TiO2 raw material, the visible light and near-infrared absorptivity of the flame sprayed TiO2 is significantly enhanced. The addition of SiO2 promotes the rutile-to-anatase phase transformation and appearance of Ti3+ species. The prepared sample with a composition of 40 at.% TiO2–60 at.% SiO2 exhibits the highest absorption of above 95% in 0.79–2.5 µm, and the highest emissivity of above 0.96 in 3–5 µm and 8–14 µm. The black TiO2–SiO2 microspheres with enhanced photo-absorption properties can be used as a promising optical-thermal conversion material.