Construction of TiO 2 -pillared multilayer graphene nanocomposites as efficient photocatalysts for ciprofloxacin degrada
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Construction of TiO2-pillared multilayer graphene nanocomposites as efficient photocatalysts for ciprofloxacin degradation Xiong-feng Zeng, Jian-sheng Wang, Ying-na Zhao, Wen-li Zhang, and Meng-huan Wang Hebei Provincial Laboratory of Inorganic Nonmetallic Materials, College of Materials Science and Engineering, North China University of Science and Technology, Tangshan 063210, China (Received: 23 July 2020; revised: 9 September 2020; accepted: 11 September 2020)
Abstract: We successfully constructed TiO2-pillared multilayer graphene nanocomposites (T-MLGs) via a facile method as follows: dodecanediamine pre-pillaring, ion exchange (Ti4+ pillaring), and interlayer in-situ formation of TiO2 by hydrothermal method. TiO2 nanoparticles were distributed uniformly on the graphene interlayer. The special structure combined the advantages of graphene and TiO2 nanoparticles. As a result, T-MLGs with 64.3wt% TiO2 showed the optimum photodegradation rate and adsorption capabilities toward ciprofloxacin. The photodegradation rate of T-MLGs with 64.3wt% TiO2 was 78% under light-emitting diode light irradiation for 150 min. Meanwhile, the pseudofirst-order rate constant of T-MLGs with 64.3wt% TiO2 was 3.89 times than that of pristine TiO2. The composites also exhibited high stability and reusability after five consecutive photocatalytic tests. This work provides a facile method to synthesize semiconductor-pillared graphene nanocomposites by replacing TiO2 nanoparticles with other nanoparticles and a feasible means for sustainable utilization of photocatalysts in wastewater control. Keywords: pillared structure; titanium dioxide-pillared multilayer graphene nanocomposites; photocatalysis; ciprofloxacin
1. Introduction Ciprofloxacin (CIP), a synthetic third-generation fluoroquinolone antibiotic, has widely been used for the efficient treatment of a number of bacterial infections [1]. However, the bio- and photo-degradation of CIP are difficult [2]. Hence, the investigation of the photocatalytic degradation of CIP by solar energy as a potential way to solve water pollution has attracted extensive research attention [3–8]. TiO2 is the most widely studied and used as a photocatalyst in commercial applications because of its advantages [9–10]. However, the wide band gap and high photoelectron– hole recombination probability hinder the improvement of the photocatalytic performance of TiO2 [11]. Strategies, including doping, nanostructuring, surface modification, and heterojunction construction, have been proposed to enhance the semiconductor properties of TiO2 [7,12–16]. Graphene possesses a large specific surface area, excellent conduction, and chemical stability [17], resulting in good electron transfer and electron holding capacity. When TiO2 combines with graphene, the photocatalytic activity of graphene–TiO2 compositions is higher compared with pure TiO2 [18–21] because of the effective charge transfer. Graphene–TiO2 nano-
composites can be used not only in photocatalysis but also in dye-sensitized solar cells, ultraviolet phot
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