Construction of a novel Ag/Ag₃PO₄/MIL-68(In)-NH₂ plasmonic heterojunction photocatalyst for high-efficiency photocatalysis

To boost the visible light catalytic performance of typical metal-organic frameworks (MOFs) materials (MIL-68(In)-NH₂), a novel stable Z-scheme Ag/Ag₃PO₄/MIL-68(In)-NH₂ plasmonic photocatalyst was constructed by electrostatic attraction, co-precipitation reaction, and in-situ photoreduction reaction methods for the first time. The photocatalytic activities of the photocatalysts are systematically explored by the photocatalytic degradation of bisphenol A (BPA) and reduction of Cr(VI) under visible light. Ag/Ag₃PO₄/MIL-68(In)-NH₂ displays the best photocatalytic performance among the as-prepared photocatalysts. The rate constant of BPA degradation on Ag/Ag₃PO₄/MIL-68(In)-NH₂ is 0.09655 min⁻¹, which is better than many reported photocatalytic materials. It also achieved a maximum rate constant of 0.02074 min⁻¹ for Cr(VI) reduction. The boosted photocatalytic performance is due to the improved absorption caused by localized surface plasmon resonance (LSPR), effective interface charge transfer and separation, and more reactive sites provided by the large specific surface area. Besides, the photocatalytic degradation pathway of BPA is concluded according to GC-MS analysis. Finally, a more reasonable Z-scheme mechanism is speculated and verified through a series of characterizations and simulations, such as time-resolved photoluminescence spectroscopy (TRPL), electron spin resonance (ESR), and finite difference time domain (FDTD) method.