Exploring the effect of morphologies of Fe(III) metal-organic framework MIL-88A(Fe) on the photocatalytic degradation of rhodamine B

Metal-organic frameworks built from [Fe3(μ3-O)(COO)6] clusters and fumaric acid ligand, the so-called MIL-88 A(Fe) is a well-known environment-friendly promising material for many applications. In this paper, three different morphologies of MIL-88 A(Fe) such as rod, diamond and spindle have been synthesized separately by reacting FeCl3•6H2O and fumaric acid in 1 : 1 metal-ligand stoichiometric ratio using two different solvents such as water and DMF via hydrothermal method. The morphology of the products and their particle sizes were obtained using SEM and three distinct morphologies viz., rod, diamond and spindle were clearly distinguished by TEM. All the three samples were characterized by FT-IR, PXRD, UVDRS, PL, XPS and BET, and the effect of the morphologies of MIL-88 A(Fe) on the photocatalytic degradation of Rhodamine B (RhB) was studied under sunlight. The addition of an H2O2 electron acceptor can markedly enhance the photocatalytic Rhodamine B degradation of MIL-88 A(Fe). Among these three, rod-shaped morphology of MIL-88 A(Fe) shows the higher photocatalytic effect for the degradation of Rhodamine B under sunlight due to its lower band gap, high surface area, and lower electron-hole recombination rate which enable them the transfer of electrons for the photocatalytic degradation. We found that 98% degradation of RhB in 50 min has taken place by using r-MIL-88 A(Fe) as the catalyst under sunlight.</p

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

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), namelyMAG-1andMAG-2(stoichiometric ratio of Fe to Ag is 5:1 and 2:1), were successfully synthesizedviafacilein situhydrothermal 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 ofp-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 usingMAG-2as 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).</p

A 0D/2D Heterojunction Composite of Polymeric Carbon Nitride and ZIF-8-Derived ZnO for Photocatalytic Organic Pollutant Degradation

Solar photocatalytic technology based on semiconducting materials has gained the attention of the scientific community to solve the energy crisis and environmental remediation. Zeolitic imidazolate frameworks (ZIFs) are a subfamily of metal–organic frameworks (MOFs) with the isomorphic topologies of zeolites and coordinative compositions of MOFs. Owing to high specific surface areas, tunable channels and high thermal stabilities, zeolitic imidazolate frameworks (ZIFs) have been used in catalytic applications. In this paper, ZIF-8 was used as a matrix to synthesize 0D/2D heterojunction photocatalysts, viz., ZnO/C3N4-x% (x = 2.5, 5 and 10), for the photocatalytic degradation study of rhodamine B (RhB). The synthesized composite materials were characterized using FTIR, PXRD, UVDRS, PL, TEM, and BET analyses. TEM images showed the nearby contacts between ZnO and C3N4 in the hybrid and the uniform distribution of ZnO on the surface of the C3N4 nanosheet, thus increasing the development of 0D/2D heterojunction. The hybrid system ZnO/C3N4-5% (ZCN-5) showed good photocatalytic activity for the degradation of RhB under sunlight. A possible mechanism for the improved photocatalytic activity of the ZnO/C3N4 composite is also suggested. This exploratory study demonstrates the effective separation and migration of photo-induced electron–hole pairs between the 2D C3N4 sheet and 0D ZnO for the improved performance of heterojunction photocatalysts