Catalyst-Free Biphasic Orthorhombic/Hexagonal Tungsten Oxide System with Enhanced Photocatalytic Response Under Visible Light

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) methyl violet (MV), respectively. The XRD, RAMAN, TEM, and UV-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.