Role of particle size for platinum-loaded tungsten oxide nanoparticles during dye photodegradation under solar-simulated irradiation

► Pt-WO3 nanoparticles as photocatalyst for dye degradation. ► Pt-WO3 photocatalyst is active under solar-simulated irradiation. ► Optimal size for Pt-WO3 nanoparticles is 18 to 26.4 nm. ► At the optimal size, Pt-WO3 exhibits a 3.5-fold higher rate compared to other sizes.