Synthesis and characterization of tungsten trioxide (WO3) as photocatalyst against wastewater pollutants

Abstract

In this work, crash precipitation technique was employed to synthesize a visible light-responsive tungsten trioxide (WO3) photocatalyst using ammonium paratungstate as tungsten precursor. The spray-dried (120 °C) and calcined (600 °C) WO3 powder was characterized by analyzing methods of XRD, PSD, BET and BJH, Raman, FESEM/EDX, FTIR, UV–vis DRS and XPS spectroscopy. X-ray diffraction (XRD) and Raman studies confirm the well crystalline monoclinic crystal structure. Scanning electron microscopy (SEM) images showed micron-sized spherical bulks of WO3 particles with needle-like morphology. A normal distribution with a d 50 (median diameter) value of 6.0 μm was observed with particle size analysis. Much enhanced BET surface area of 102 g/m2 with wide pore size 1.8 nm is measured compared to commercially available WO3 that results in increased pollutants surface adsorption. Fourier transform infrared spectroscopy (FTIR) study demonstrated that the calcined sample surface is enriched with bonded hydroxyl groups, beneficial for powder particles activity. Photocatalyst band gap was calculated by considering the absorbance measurements recorded on UV–vis diffuse reflectance spectroscopy (DRS). The energy value of 2.6 eV was calculated which lies in the visible light region while X-ray photoelectron spectroscopy (XPS) analysis showed 6 + oxidation state for tungsten. Bulk WO3 sphere photocatalytic activity was evaluated through the exertion of synthetic textile methylene blue (MB) dye and sulfamethoxazole (SMX) pharmaceutical antibiotic. The obtained activity results showed 85% and 100% degradation for MB and SMX under 100 min visible light irradiation. We expect that our work may provide a new sample for energy production (H2) through water photolysis, gas sensing and soft matter research.