Z-scheme BiVO4/Ag/Ag2S composites with enhanced photocatalytic efficiency under visible light

Abstract

The Z-scheme BiVO₄/Ag/Ag₂S photocatalyst was fabricated via a two-step route. The as-prepared samples were characterized by XRD, FE-SEM, HRTEM, XPS and UV-vis diffuse reflectance spectroscopy. The results of PL and photocurrent response tests demonstrate that the ternary BiVO₄/Ag/Ag₂S composites had a high separation and migration efficiency of photoexcited carriers. As a result, the ternary photocatalyst exhibits enhanced photocatalytic activity for decomposing Rhodamine B (RhB) under LED light (420 nm) irradiation. The results of trapping experiments demonstrate both h⁺ and ˙OH play crucial roles in decomposing RhB molecules. Additionally, the energy band structures and density of states (DOS) of BiVO₄ and Ag₂S were investigated via the density functional theory (DFT) method. Finally, a Z-scheme electron migration mechanism of BiVO₄ → Ag → Ag₂S was proposed based on the experimental and calculated results.