MoS2/WO3 heterojunction with the intensified photocatalytic performance for decomposition of organic pollutants under the broad array of solar light

Abstract

Heterojunction photocatalysts have emerged as a stronger candidate for the decomposition of noxious pollutants in contrast to the single-component system. Herein, the binary composites of MoS2/WO3 (MSW) of the different weight ratios were synthesized by the hydrothermal method. Various analytical techniques were performed to investigate the structural, optical (band gap value is 2.5 eV), morphological as well as surface chemical composition of the as-prepared catalysts. A mean pore volume of 6.024 cm3/g, favourable surface area of 26 m2/g, and a pore diameter of 32.31 nm were all validated by surface area analyses. The creation of strong interfacial contact between MoS2 and WO3 caused the charges to be separated for a long time. The degradation of rhodamine B dye (Rh B) and colorless thiamethoxam (TM) under the influence of solar light was used to test the photocatalytic performance of the as-prepared catalyst. The maximum degradation efficiency of 90.20%, and 92.60% with the rate constant of 0.020 min−1, and 0.01858 min−1 was achieved for the photocatalytic degradation of TM, and Rh B, respectively using optimum ratio (1:3 MSW) in 120 min. The photocatalyst's effectiveness was further tested by reusability experiments (5 runs) and the characterization results afterwards indicated the intactness of crystalline planes that is responsible for high efficacy. The percent chemical oxygen demand (% COD) removal of ∼66.6 and 57.14% was attained for Rh B and TM, respectively while percent total organic carbon (% TOC) removal for these pollutants was around 49.5 and 76.48%, respectively after 120 min. The % COD and TOC removal of the real industrial waste water (WW) was analyzed to be 80 and 78.9%, respectively. The scavenger studies were performed to discover the primary reactive species. The gas chromatography-mass spectrometry (GC–MS) study was also carried out to investigate the intermediates and products formed in the photodegradation process of TM. The photocatalytic decomposition mechanism of the organic pollutants via MSW photocatalyst was finally proposed.