Fabrication of AgI/BiPO_4 n-n heterojunction photocatalyst for efficient degradation of organic pollutants

摘要

The AgI/BiPO_4 n-n heterojunction hybrids were favorably fabricated over amorphous particles AgI closely in contact with petty polyhedron-assembled star-like BiPO_4 by precipitation technology for the first time. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectra (DRS), electrochemical test, etc. The degradation of tetracycline hydrochloride (TC) and methylene blue (MB) was employed to testify the performance of as-prepared composites upon exposure of simulated solar light and the AB-X composites exhibited boosted degradation efficiency in comparison with the as-prepared pure BiPO_4 and AgI. For instance, the calculated k_(TC) of pseudo-first-order kinetics model on 24 wt% AgI/BiPO_4 sample was 36 times relative to those on pure BiPO_4. This enhanced activity might due to increased charge transfer and separation efficiency in the formed n-n heterojunction and the dominant reaction active species were authenticated by trapping experiments. Furthermore, the internal electric field in the AgI/BiPO_4 heterojunction and the transfer path of electron-holes were tentatively deduced through graphical elucidation.