Electric fields and local magnetic field enhance Ag-BiVO_4-MnO_x photoelectrochemical and photocatalytic performance

摘要

The Ag-BiVO4-MnOx multi-stage interface heterojunction photocatalyst is prepared via photo-deposition method. The oxidation co-catalyst MnOx and reduction co-catalyst Ag are selectively deposited onto (0 1 0) and (1 1 0) facets of BiVO4. Under ultraviolet (UV) light, MnOx is deposited onto the BiVO4 (1 1 0) facet, causing its energy band to move upward and bend at the interface to produce a p-n junction and a built-in electric field that points from BiVO4 towards MnOx. Simultaneously, the difference in energy levels allows the BiVO4 to form surface heterojunction and produce a built-in electric field that points from (0 1 0) facet towards the (1 1 0) facet. A Schottky junction is formed when Ag is deposited onto the BiVO4 (0 1 0) facet to create space charge region without free carriers. A built-in electric field is formed that points from Ag to BiVO4. The electric fields generated via light excitation and a local magnetic field formed by plasmonic Ag improve the photocatalytic activity of the Ag-BiVO4-MnOx photocatalyst, the degradation rate of Ag-BiVO4-MnOx is 5.9 times higher than that of the BiVO4. This work not only promotes the separation efficiency of photogenerated charge carriers, but also pays attention to the synergistic effect of electric fields generated by light excitation and local magnetic field formed by plasmonic Ag, which provides a new idea for photocatalysis research.