Fabrication of Visible Light Active MoS2–W–Cu Ternary Heterojunction for Enhanced Photocatalytic Degradation

Abstract

The increase in environmental pollution has led to a novel ternary photocatalytic system for remediation. These photocatalytic systems exhibit superior visible light active band gap of Mo_0.99W_0.005Cu_0.005S₂. A highly effective visible light active ternary heterojunction was fabricated using the hydrothermal method. Herein, it reports the hydrothermal synthesis of MoS₂–W–Cu as a photocatalyst, efficiently exhibiting greater photocatalytic activity for wastewater treatment under visible light. The photocatalytic degradation of methylene blue in aqueous suspension has been employed to evaluate the visible light photocatalytic activity of the prepared samples. The blue shift in the absorption onset confirms the size quantization of pure and doped MoS₂ nanoparticles, which act as effective and stable catalysts, making  it  possible  to  utilize visible light  in  photocatalysis. The  as-prepared  samples  were characterized  using  field  emission  scanning  electron  microscope,  energy dispersive X-ray analysis,  X-ray diffraction, UV-visible, and UV-visible differential reflectance spectroscopy techniques. The characteristic Bragg peaks of Mo_0.99W_0.005Cu_0.005S₂ are reduced, indicating the possible formation of layered MoS₂. The field emission scanning electron microscope morphologies of MoS₂, Mo_0.99W_0.01S₂, and Mo_0.99W_0.005Cu_0.005S₂ are disordered, and nanorods were induced in the hydrothermal method. The calculated band gap of the novel photocatalyst was found from the differential reflectance spectroscopy plot, which helped in understanding the photo-induced electron–hole pair's recombination. Mo_0.99W_0.005Cu_0.005S₂ doping of ternary sample, which increases the photocatalytic degradation, was studied in detail and the experimental result is reported.