LED-Assisted Degradation of Aromatic Organics Using Cu 2 O Photocatalysts
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LED-Assisted Degradation of Aromatic Organics Using Cu2O Photocatalysts 1
Yang Su1, Hanbin Ma1, and Arokia Nathan1 Electrical Division, Department of Engineering, University of Cambridge, U.K.
ABSTRACT In this work, we successfully synthesized rhombic dodecahedral Cu2O nanocrystals with a size of 300 – 400 nm using a facile hydrothermal method. The as-prepared photocatalyst with narrow bandgap is activated using low power visible LED light sources and shows high efficiency in degrading aromatic organic compounds including toluene and chlorobenzene. The OH substitution leads to oxidation/ionization potential drops while the nature of the p-type Cu2O contributes to an effective single electron transfer reaction. INTRODUCTION Aromatic organic compounds widely exist in industrial wastewater at high toxicity levels, causing serious ecological pollution. Conventional biological treatment methods are not suitable for industrial wastewater because of the high concentration of aromatic compounds. Photocatalysis could potentially serve as a clean and low-cost technology for industrial wastewater treatment and the degradation of various categories of organics have been reported [1,2,3]. Conventional photocatalyst materials e.g. TiO2, needs to be activated by UV light in view of its large bandgap thus limiting its application. Cuprous oxide (Cu2O), as a typical p-type semiconductor with a narrow band gap of 2-2.2 eV, can be activated by visible light. The Cu2O photocatalyst has attracted much research interests and its morphology-dependent properties have received considerable attention. A large number of Cu2O structures have been reported [4,5,6,7]. Rhombic dodecahedral structure with all active (110) facets has been reported to show higher photocatalytic reactivity than other architectures [8]. Dyes including methyl orange, methyl blue, Congo red, etc. have been frequently used for photocatalysis experiments [9,10,11] while only sporadic works have been published on the degradation of aromatic organics [12]. The degradation of aromatic organics is reported to be initiated by single-electron transfer (SET) chemistry and hydroxyl-like chemistry [13], while the pathway and capability of degrading aromatic compounds using Cu2O photocatalyst is still unclear. In this work, we successfully synthesized uniform 300 - 400 nm rhombic dodecahedral Cu2O nanocrystals through a hydrothermal method. The as-prepared nanocrystals were characterized using SEM, TEM, UV-vis spectra, XRD and XPS techniques. The ability to degrade aromatic organics were tested using chlorobenzene and toluene solutions. The degradation mechanism is studied using the GC/MS system. The as-prepared Cu2O photocatalyst has demonstrated high reactivity towards the degradation of aromatic organics and the potential to serve as a green strategy for industrial wastewater treatment.
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