Enhanced photocatalytic activity and easy recovery of visible light active MoSe2/BiVO4 heterojunction immobilized on Luffa cylindrica – experimental and DFT study

Abstract

Nanostructured bismuth vanadate (BiVO₄) and molybdenum diselenide (MoSe₂) heterostructures were prepared by varying the concentration of MoSe₂ from 0.05 to 0.2 mol%. The synthesized photocatalysts were used to degrade methylene blue (MB) and phenol and the best activity was found for the 0.15 mol% MoSe₂/BiVO₄ heterostructure. To address the recovery issue of the photocatalyst from the slurry, 0.15 mol% MoSe₂/BiVO₄ was immobilized on Luffa cylindrica, which not only solved the recovery problem but also increased the photocatalytic efficiency. The immobilized material showed degradation of MB and phenol up to ∼97% within 2 hours of visible light irradiation. The as-prepared samples were characterized for scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) technique, diffuse reflectance spectroscopy (DRS), and Fourier transformation infrared (FT-IR) spectroscopy to study the improved catalytic efficiency and gain a deeper understanding of interface formation in the heterojunction. Photoelectrochemical studies were also carried out for all the samples and the highest photocurrent density was achieved in 0.15 mol% MoSe₂/BiVO₄ compared to other samples. Calculations based on first-principles density functional theory (DFT) have also provided an insightful understanding of the interface formation, physical mechanism, and superior photocatalytic performance of the MoSe₂@BiVO₄ heterostructure over other samples.