Fabrication of a magnetically separable and dual Z-scheme PANI/Ag3PO4/NiFe2O4 composite with enhanced visible-light photocatalytic activity for organic pollutant elimination

A novel polyaniline/silver phosphate/nickel ferrate (PANI/Ag3PO4/NiFe2O4) magnetic photocatalyst has been successfully fabricated by a precipitation-hydrothermal method. The composition, morphological structure and optical property of the as-prepared samples are characterized. All the PANI/Ag3PO4/NiFe2O4 composites with different PANI content show enhanced visible-light photocatalytic activity for rhodamine B (RhB) and methyl orange (MO) dyes degradation compared to pure Ag3PO4, Ag3PO4/NiFe2O4 and Ag3PO4/PANI composites. The highest degradation efficiency for RhB and MO via 3%-PANI/Ag3PO4/NiFe2O4 composite photocatalyst separately reach 100% and 94.97%, and their degradation rate (k) are close to 12.1 and 15.4 times faster than those of pure Ag3PO4, respectively. Meanwhile, the PANI/Ag3PO4/NiFe2O4 composite displays excellent photocatalytic performance on the degradation of colorless organic pollutants (tetracycline hydrochloride, nitrobenzene and bisphenol A) under the visible light irradiation. The PANI/Ag3PO4/NiFe2O4 catalyst exhibits a superior stability than pure Ag3PO4 after three consecutive reuses. The improved photocatalytic activity and stability of PANI/Ag3PO4/NiFe2O4 ternary composite can be attributed to the extended absorption capability in the visible light region as well as the high-efficiency separation of electron-hole pairs. Particularly, the construction of double Z-scheme heterojunctions in the ternary composite can facilitate the rapid transfer of electrons on the surface of Ag3PO4, thus inhibit its photocorrosion. This study provides an idea for enhancing the anti-photocorrosion and photocatalytic activity of photosensitive semiconductors.