B and N co-doped anatase, rutile, and brookite TiO2 (abbreviated as BN-Ana, BN-Rut, and BN-Bro) were successfully synthesized. The apparent color of as-obtain BN-Ana, BN-Rut and BN-Bro was red, cyan and yellow-green, respectively. The mechanisms of various coloring were concluded as the different band gap configurations and the formation of covalent B-N bonding. The nitridation time expressed less effect on changing the color. On the contrary, nitridation temperature enabled the distinct color changes by altering the brightness. Lower temperature, fewer doping concentration, and brighter apparent color, vice versa. Through tuning the brightness, a gradient of yellow-orange-red was achieved in the case of BN-Ana, as well the transitions of grey-to-cyan and white-to-pale-yellow were achieved in BN-Rut and BN-Bro, respectively. This research proposed a method for the synthesis of color-full titania pigment without the addition of other toxic transition metal elements.
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