Preparation, characterization and thermal performance evaluation of coating colored with NIR reflective pigments: BiVO4 coated mica-titanium oxide

A series of environmentally nontoxic near-infrared reflective pigments of BiVO4 coated mica-titanium oxide were synthesized. The pigments were characterized by XRD, FE-SEM, UV-vis-NIR spectrophotometer and CIE L∗ a∗ b∗ color scales. The results illustrated that the BiVO4 particles with a size of ∼500 nm were firmly adhered to mica-titanium oxide substrate. Additionally, the composite pigments change the color from white to bright yellow with the increase of the BiVO4 loadings. All the pigments had higher NIR reflectance than conventional yellow pigment (≥70.0%). In the simulated experiment, the temperature difference of the inner surface temperature of coatings and the interior air temperature of boxes reached 4.5 °C and 2.3 °C, respectively, indicating that the good thermal insulation performance of the sample coating (30% BiVO4) could be used as building roof material to reduce the heat buildup and decrease the indoor temperature. Furthermore, we also evaluated aging resistance of the pigments. In conclusion, BiVO4 coated mica-titanium oxide composite pigments have great potential in serving as cool materials for building coatings and they also meet energy-saving and environmentally friendly requirements.