MIL-101(Fe)/g-C3N4 for enhanced visible-light-driven photocatalysis toward simultaneous reduction of Cr(VI) and oxidation of bisphenol A in aqueous media

Heterostructured composites with an excellent photocatalytic activity have attracted increasing attention because of their great application in environmental remediation. Herein, a MIL-101(Fe)/g-C3N4 heterojunction was synthesized via in-situ growth of MIL-101(Fe) onto g-C3N4 surface. The heterojunctions were applied as a bifunctional photocatalyst for simultaneous reduction of Cr(VI) and degradation of bisphenol-A (BPA) under visible light and exhibited an obvious enhancement in photocatalytic performance compared with MIL-101(Fe) or g-C3N4. The improved activity could be attributed to the enhanced light absorption and efficient charge carrier separation by forming a direct Z-scheme heterojunction with appropriate band alignment between MIL-101(Fe) and g-C3N4. The radical trapping and electron spin resonance showed that photo-generated electrons are responsible for the reduction of Cr(VI) and BPA degradation, following an oxygen-induced pathway. This work provides new insight into the construction of metal-free semiconductor/MOFs heterojunctions as a bifunctional visible-light-driven photocatalyst for efficient and simultaneous treatment of multiple toxic pollutants in water.

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Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu, Feiping Zhao
2020
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Abstract

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https://infoscience.epfl.ch/record/277745?ln=en

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Related concepts (6)

Electron paramagnetic resonance

Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944, and was developed independently at the same time by Brebis Bleaney at the University of Oxford.

Heterojunction

A heterojunction is an interface between two layers or regions of dissimilar semiconductors. These semiconducting materials have unequal band gaps as opposed to a homojunction. It is often advantageous to engineer the electronic energy bands in many solid-state device applications, including semiconductor lasers, solar cells and transistors. The combination of multiple heterojunctions together in a device is called a heterostructure, although the two terms are commonly used interchangeably.

Photocatalytic water splitting

Photocatalytic water splitting is a process that uses photocatalysis for the dissociation of water (H2O) into hydrogen (H2) and oxygen (O2). Only light energy (photons), water, and a catalyst(s) are needed, since this is what naturally occurs in natural photosynthetic oxygen production and CO2 fixation. Photocatalytic water splitting is done by dispersing photocatalyst particles in water or depositing them on a substrate, unlike Photoelectrochemical cell, which are assembled into a cell with a photoelectrode.