Ag/AgCl@MIL-88A(Fe) heterojunction ternary composites: towards the photocatalytic degradation of organic pollutants

Abstract

The efficient utilization of solar energy has received tremendous interest due to the increasing environmental and energy concerns. The present paper discusses the efficient integration of a plasmonic photocatalyst (Ag/AgCl) with an iron-based metal–organic framework (MIL-88A(Fe)) for boosting the visible light photoreactivity of MIL-88A(Fe). Two composites of Ag/AgCl@MIL-88A(Fe), namely MAG-1 and MAG-2 (stoichiometric ratio of Fe to Ag is 5 : 1 and 2 : 1), were successfully synthesized via facile in situ hydrothermal methods followed by UV reduction. The synthesized composite materials are characterized by FTIR, PXRD, UVDRS, PL, FESEM/EDX, TEM and BET analyses. The Ag/AgCl@MIL-88A(Fe) (MAG-2) hybrid system shows excellent photocatalytic activity for the degradation of p-nitrophenol (PNP), rhodamine B (RhB), and methylene blue (MB) under sunlight. We found that 91% degradation of PNP in 80 min, 99% degradation of RhB in 70 min and 94% degradation of MB in 70 min have taken place by using MAG-2 as a catalyst under sunlight. The superior activity of Ag/AgCl@MIL-88A(Fe) (MAG-2) is attributed to the synergistic effects from the surface plasmon resonance (SPR) of Ag NPs and the electron transfer from MIL-88A(Fe) to Ag nanoparticles for effective separation of electron–hole pairs. Furthermore, the mechanism of degradation of PNP, RhB and MB is proposed by analyzing the electron transfer pathway in Ag/AgCl@MIL-88A(Fe).