Novel near infrared reflective pigments based on hollow glass microsphere/BiOCl1-xIx composites: Optical property and superhydrophobicity

In this work, BiOCl1,I-x(x) coated hollow glass microsphere was synthesized as a novel near infrared reflective pigment for superhydrophobic cool roof coatings. BiOCl1-I-x(x) microflowers or microspheres were deposited on hollow glass microspheres using a simple chemical liquid deposition method. The morphologies of BiOCI1-x.I-x were found to differ drastically by varying the molar ratio of Cl to I. The color of the composite pigments changed from white to red and the band gap decreased from 3.16 eV to 1.87 eV as the increased content of I. The near infrared solar reflectance of the composite pigment was as high as 0.947. An approximately 8 C decrease in outer surface temperature was obtained for the heat box coated with the composite pigments. With the help of the micro/nano-scale surface roughness of hollow glass microsphere/BiOCl1-xIx composites, a superhydrophobic coating with a contact angle of 156.1 could be obtained. The superhydrophobic cool coating showed good antifouling property when they were fouled by the slurry solution containing montmorillonite and Rhodamine B. Moreover, the prepared superhydrophobic coatings exhibited long term stability and ultraviolet durability. Therefore, such superhydrophobic cool coatings with antifouling property is able to work for a longer time by preventing the contamination for building thermal insulation.