Iridium nanoparticles anchored WO3 nanocubes as an efficient photocatalyst for removal of refractory contaminants (crystal violet and methylene blue)

Abstract

A series of novel visible light driven Iridium loaded WO3 (Ir/WO3) nanocomposites were successfully synthesized via single step hydrothermal process. The Ir/WO3 nanocomposites were systematically characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and UV–vis diffused reflectance spectra (UV–vis DRS) techniques. The WO3 nanocparticles were showed nanocubes-like structure and Ir NPs were anchored on surface of WO3 which was confirmed by SEM and TEM analysis. Optical result indicated that the absorption band edge is positioned in the visible region with band gap energy of WO3, Ir/WO3 (1%), Ir/WO3 (3%) and Ir/WO3 (5%) was 2.87, 2.8, 2.6 and 2.5 eV, respectively. From EDX and XPS analysis, Ir/WO3 nanocomposite contains Ir, W and O elements only. The Ir/WO3 nanocatalysts have been utilized for the photodegradation of crystal violet (CV) and methylene blue (MB) organic pollutants under the visible light irradiation. Compared to pure WO3 and other Ir/WO3 nanocomposites, 3% loaded Ir/WO3 catalyst exhibited superior photocatalytic efficiency towards the degradation of CV and MB. The enhancement of photocatalytic activity was mainly due to the presence of Ir nanoparticles on the surface of WO3 nanocubes preventing the photogeneration electrons-holes pair recombination and the synergistic bonding interaction between Ir NPs and WO3 nanocubes. Various factors such as Ir loading concentration, effect of catalyst, effect of pollutants and stability of the photocatalyst were explained. Furthermore, the possible photocatalytic mechanism of Ir/WO3 catalyst was determined by radical trapping studies. This novel Ir/WO3 nanocomposite proved to an efficient tool catalyst for the organic contaminants abatements.