Rapid large-scale preparation of ZnO nanowires for photocatalytic application
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NANO EXPRESS
Open Access
Rapid large-scale preparation of ZnO nanowires for photocatalytic application Chunyu Ma1, Zhihua Zhou1,2†, Hao Wei1, Zhi Yang1, Zhiming Wang2 and Yafei Zhang1*†
Abstract ZnO nanowires are a promising nanomaterial for applications in the fields of photocatalysis, nano-optoelectronics, and reinforced composite materials. However, the challenge of producing large-scale ZnO nanowires has stunted the development and practical utilization of ZnO nanowires. In this study, a modified carbothermal reduction method for preparing large-scale ZnO nanowires in less than 5 min is reported. The preparation was performed in a quartz tube furnace at atmospheric pressure without using any catalysts. A mixed gas of air and N2 with a volume ratio of 45:1 was used as the reactive and carrier gas. About 0.8 g ZnO nanowires was obtained using 1 g ZnO and 1 g graphite powder as source materials. The obtained nanowires exhibited a hexagonal wurtzite crystal structure with an average diameter of about 33 nm. Good photocatalytic activity of the nanowires toward the photodegradation of methylene blue dye under UV irradiation was also demonstrated. Introduction Organic dyes widely used in rubber, textiles, and plastics industries are one of the largest groups of pollutants released into wastewaters [1]. They have caused severe environmental contamination because of potential toxicity of the dyes and their visibility in water bodies. Degradation and removal of them are a vital matter for protecting the environment. However, the traditional techniques for treating organic dyes are usually nondestructive, ineffective, and costly or just transfer pollutions from water to another phase [2]. Recently, it has been reported that ZnO can be an alternative to conventional treatments for removing dye pollutants from water [3]. ZnO, with a lower cost, absorbs over a larger fraction of UV spectrum and absorbs more light quanta than TiO 2 [4]. When an appropriate light source illuminates ZnO, electron/hole pairs will be produced with electrons absorbing the light energy, transitioning to the conduction band and leaving positive holes in the valence band [5]. The produced electron/hole pairs induce a complex series of reactions that might lead to the complete degradation of the dye * Correspondence: [email protected] † Contributed equally 1 Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao tong University, Shanghai 200240, China Full list of author information is available at the end of the article
pollutants adsorbed on the semiconductor surface. Specifically, ZnO nanowires have demonstrated excellent photocatalytic activity because of their larger surface area and higher surface state [6]. Until now, there are various techniques, such as chemical vapor deposition [7], physical vapor deposition [8], electrodeposition [9,10], and thermal evaporation [11] that can be used to synthesize ZnO nanowires. These methods have made great con
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