Synthesis of WO3 nanoparticles for photocatalytic O2 evolution by thermal decomposition of ammonium tungstate loading on g-C3N4

Tungsten trioxide (WO3) nanoparticles have been successfully synthesized by thermal decomposition of ammonium tungstate loading on g-C3N4. The as prepared nanoparticles were characterized by XRD, UV–vis, photoluminescence spectra (PL) and TEM. The XRD results indicate that the g-C3N4 decomposed completely with WO3 remaining at calcination temperature higher than 550 °C. The WO3 prepared at temperature below 750 °C exhibits orthorhombic phase, and monoclinic phase at temperature higher than 850 °C. The UV–vis absorption onset wavelength of the obtained samples is approximately 470 nm, and the absorption intensity increases with calcination temperature, and reaches a maximum at 750 °C. The as prepared WO3 powders, loaded with 0.5 wt% Pt as cocatalyst, were used as photocatalysts for O2 evolution from an aqueous KIO3 solution. The WO3 nanoparticles prepared from ammonium tungstate loading on g-C3N4 showed photocatalytic activity in O2 evolution up to 77 times higher than that of WO3 samples prepared from ammonium tungstate without loading on g-C3N4.