Brilliant Yellow, Transparent Pure, and SiO2-Coated BiVO4 Nanoparticles Made in Flames

Abstract

Transparent, yellow bismuth vanadate nanoparticles were made by flame spray pyrolysis. These materials are of special interest as brilliant yellow pigments. The structural properties of the as-prepared powders were characterized by X-ray diffraction, Raman spectroscopy, nitrogen adsorption, transmission electron microscopy, zeta potential measurements, and photospectroscopy. Depending on the particle collection temperature, either pale, amorphous materials or brilliant yellow-green, crystalline BiVO4 with particle size of about 50 nm were formed by direct calcination above 300 °C. The addition of Si during flame synthesis of BiVO4 resulted in smaller such crystals of about 20 nm that were embedded in silica. This prevented sintering of the BiVO4 particles during calcination at 400 °C and resulted in thermally stable, highly transparent, yellow particles.