Solar spectral optical properties of rutile TiO2 coated mica–titania pigments

•Rutile TiO2 coated mica–titania pigments were prepared at 70 °C.•SnO2 as a rutile promoting additive was deposited onto mica prior to TiO2.•Rutile TiO2 films were composed of nanoneedles or nanoflower structures.•The rutile pigments exhibit high NIR reflectance.•The rutile pigments exhibit strong UV shielding property.

Different shaped rutile TiO2 coated mica–titania pigments were prepared by hydrolysis of TiCl4 ethanolic solution at 70 °C. SnO2 as a rutile promoting additive was deposited onto mica prior to TiO2. The use of TiCl4 played a crucial role in controlling the morphology of rutile TiO2 coatings. Monodisperse nanoneedles were assembled into nanoflowers with an increasing particle size as the TiO2 loading increased. A possible crystal growth mechanism of rutile TiO2 with rich nanostructures was proposed. The obtained rutile samples showed stronger ultraviolet shielding ability and higher near-infrared reflectance property than that of anatase sample. What's more, the rutile TiO2 coating with smaller particle size possessed higher reflectance in the region of 1300–2500 nm in accordance with the Kubelka–Munk theory. The near-infrared solar reflectance of the rutile TiO2 coated mica–titania pigment was as high as 97%, making them good candidates for solar reflective pigments.

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