A facile two-step hydrothermal preparation of 2D/2D heterostructure of Bi2WO6/WS2 for the efficient photodegradation of methylene blue under sunlight

Muhammad Fiaz; Manzar Sohail; Ayman Nafady; Geoffrey Will; Md A Wahab

doi:10.1016/j.envres.2023.116550

A facile two-step hydrothermal preparation of 2D/2D heterostructure of Bi₂WO₆/WS₂ for the efficient photodegradation of methylene blue under sunlight

Environ Res. 2023 Oct 1:234:116550. doi: 10.1016/j.envres.2023.116550. Epub 2023 Jul 16.

Authors

Muhammad Fiaz¹, Manzar Sohail², Ayman Nafady³, Geoffrey Will⁴, Md A Wahab⁵

Affiliations

¹ Department of Chemistry, School of Natural Sciences, National University of Sciences and Technology, Islamabad, 44000, Pakistan.
² Department of Chemistry, School of Natural Sciences, National University of Sciences and Technology, Islamabad, 44000, Pakistan. Electronic address: manzar.sohail@sns.nust.edu.pk.
³ Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
⁴ Energy and Process Engineering Laboratory, School of Mechanical, Medical and Process Engineering, Faculty of Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia.
⁵ Energy and Process Engineering Laboratory, School of Mechanical, Medical and Process Engineering, Faculty of Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia. Electronic address: wahab.abdul@qut.edu.au.

PMID: 37437862
DOI: 10.1016/j.envres.2023.116550

Abstract

A facile two-step hydrothermal method was successfully used to prepare a photocatalyst Bi₂WO₆/WS₂ heterojunction for methyl blue (MB) photodegradation. Fabricated photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). Band gap measurements were carried out by diffuse reflectance spectroscopy (DRS). Results indicated that the prepared heterostructure photocatalyst has increased visible light absorption. Photocatalytic performance was evaluated under sunlight irradiation for methylene blue (MB) degradation as a model dye. Variations in pH (4-10), amount of catalyst (0.025-0.1 g/L), and initial MB concentrations (5-20 ppm) were carried out, whereas all prepared catalysts were used to conduct the tests with a visible spectrophotometer. Degradation activity improved with the pH increase; the optimum pH was approximately 8. Catalyst concentration is directly related to degradation efficiency and reached 93.56% with 0.075 g of the catalyst. Among tested catalysts, 0.01 Bi₂WO₆/WS₂ has exhibited the highest activity and a degradation efficiency of 99.0% in 40 min (min) for MB. MB photodegradation follows pseudo-first-order kinetics, and obtained values of k_app were 0.0482 min^-1, 0.0337 min^-1, 0.0205 min^-1, and 0.0087 min^-1 for initial concentrations of 5 ppm, 10 ppm, 15 ppm, and 20 ppm, respectively. The catalyst was reused for six cycles with a negligible decrease in the degradation activity. Heterostructure 0.01 Bi₂WO₆/WS₂ has exhibited a photocurrent density of 16 μA cm^-2, significantly higher than 2.0 and 4.5 μA cm^-2 for the pristine WS₂ and Bi₂WO₆, respectively. The findings from these investigations may serve as a crucial stepping stone towards the remediation of polluted water facilitated by implementing such highly efficient photocatalysts.

Keywords: 2D material; Bi(2)WO(6)/WS(2) heterojunction; Methylene blue degradation; Photodegradation; Toxic dyes removal.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Catalysis
Light
Methylene Blue* / chemistry
Photolysis
Sunlight*

Substances

Methylene Blue