Catalyst-free biphasic orthorhombic/hexagonal tungsten oxide system with enhanced photocatalytic response under visible light

Abstract

Abstract These days, textile industries pose a more significant threat to surface water and groundwater sources directly or indirectly by discharging wastewater containing various dyes and organic pollutants to these water sources. The phase-junction-engineered heterogeneous photocatalysis carried out by visible light-driven semiconductor photocatalysts is opening a new window for the degradation of environmental organic pollutants. In this work, we have reported a one-step bottom-up hydrothermal synthesis of biphasic tungsten oxide (o/h-WO3) and performed a photodegradation experiment under visible light irradiation for the efficient degradation of organic pollutants such as Methylene blue (MB) and Methyl violet (MV), respectively. The X-ray diffraction, RAMAN, transmission electron microscopy and ultraviolet–Vis characterization techniques were used to investigate the structural, morphological and optical properties of the as-synthesized o/h-WO3. Moreover, the low calculated band gap (∼2.8 eV) and the anionic nature of o/h-WO3 suggest it as an efficient visible light-driven photocatalyst suitable for heterogeneous photocatalysis. The photodegradation experiment performed under visible light using o/h-WO3 photocatalyst showed better degradation efficiency of 71% and 89% for MB and MV, respectively, in 100 min. The dyes followed first-order kinetics, and their kinetic rate constants were calculated using the Langmuir–Hinshelwood model. Furthermore, the recyclability study of the photocatalyst was also performed and discussed the underlying mechanism for the photodegradation of the organic dyes.