Multicoating construction of BiVO₄@SiO₂ yellow pigment for enhanced thermal stability and acid resistance

Monoclinic bismuth vanadate (BiVO₄) as an environmentally friendly bright yellow pigment has received increasing attention over the past two decades. Unfortunately, poor thermal stability and acid resistance hinder its large-scale application in the industrial field. Herein, multicoated BiVO₄@SiO₂ yellow pigments with enhanced thermal stability and acid resistance were successfully synthesized by the hydrolysis method. The effects of process parameters such as Si/Bi molar ratio (n_Si/Bi), water bath temperature (T_b), and dropwise addition rate of water (V_d) on the preparation of BiVO₄@SiO₂ yellow pigments were systematically studied. The temperature stability of once-coated BiVO₄@SiO₂ encapsulation pigments prepared under optimized conditions can be increased from 620 to 860°C. To further improve its thermal stability and acid resistance, the BiVO₄ pigments were wrapped multiple times and its temperature and acid resistance were evaluated. The results showed that after three times wrapping, the obtained BiVO₄@SiO₂ showed optimal thermal stability and could maintain yellow color at 1200°C. The high-temperature stability and antiacid corrosion highlight the promise of its potential for commercial yellow pigments.