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.
Highlights
Nowadays, photocatalysis technology is regarded as one of the best ways to alleviate energy and environmental issues
Energy band structures and density of states (DOS) of BiVO4 and Ag2S were investigated by the density functional theory (DFT) method, in which plane-wave pseudopotential with CASTEP code was adopted
Similar phenomenon was observed in the X-ray diffraction (XRD) pattern of BiVO4/Ag/Ag2S sample and Ag2S was not detected as well
Summary
Photocatalysis technology is regarded as one of the best ways to alleviate energy and environmental issues. Prepared Z-scheme g-C3N4/Au/P25 composites with excellent photoactivity by introducing metal Au to the g-C3N4/P25 heterojunction.[34] Liu et al fabricated Z-scheme Cu2O/Au@CeO2 composites with strong redox ability by embedding Au nanoparticles in the yolk–shell Cu2O@CeO2 structure, which can effectively oxidize amines into imines.[35] Bao et al prepared efficient Z-scheme Cu2O/Cu/g-C3N4 photocatalyst for decomposing phenol via reduction route, in which partial metal Cu was preserved as a bridge for the transfer of photoexcited charge.[36] Shen et al reported that when reduced graphene oxide was introduced to a Cu2O/Fe2O3 type-II junction, the electron migration of Fe2O3 / RGO / Cu2O was con rmed in the Zscheme RGO-Cu2O/Fe2O3 composites.[37] some Zscheme photocatalysts were prepared by introducing Ag or Au to a type-II heterojunction, such as Ag2CO3/Ag/AgBr,[38] g-C3N4/ Ag/Ag3VO4 39 and Au/TiO2-gC3N4.40 it was possible that a Z-scheme photocatalytic system could be fabricated by properly adding electron mediator to a p–n or type-II heterojunction. The possible mechanism of the improved photocatalytic performance of BiVO4/Ag/Ag2S was discussed
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