Three-dimensional Z-Scheme Ag3PO4/Co3(PO4)2@Ag heterojunction for improved visible-light photocatalytic degradation activity of tetracycline

Constructing Z-scheme photocatalyst is paramount to improve the photocatalytic activity of single semiconductor materials by the efficient separation of photo-generated carriers. Herein, a novel Z-scheme photocatalyst Ag3PO4/Co3(PO4)2@Ag was successfully synthesized, which has the distinctive three dimensional (3D) structure with the Ag3PO4 rhombic dodecahedrons on the flower-like Co3(PO4)2. The ternary Ag3PO4/Co3(PO4)2@Ag heterostructure photocatalyst exhibits the highest photocatalytic activity in comparison with Ag3PO4, Co3(PO4)2 and Ag3PO4/Co3(PO4)2, which can be up to 91.2% at 60 min for the degradation of tetracycline (TC) under visible light irradiation. This enhanced photocatalytic performance is attributed to the surface plasmon resonance (SPR) of Ag to effectively broaden the absorption of visible light in composites, which is proved by the finite-difference time domain (FDTD) simulation. Moreover, the results of electron spin resonance (ESR) confirmed that the introduction of Ag nanoparticles can further facilitate the charge transfer of heterostructure Ag3PO4/Co3(PO4)2 through the route of the Z-scheme, fully retaining prominent redox ability of Ag3PO4 and Co3(PO4)2. Finally, the possible photocatalytic degradation mechanism over Ag3PO4/Co3(PO4)2@Ag was proposed and discussed in detail.