ZnO Composites Using Flow

Feb 19, 2018 - As shown in Figure 1A, the microfluidic system comprises two consecutive segments (cross-type micromixer and capillary microreactor) ma...
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Continuous synthesis of Ag/AgCl/ZnO composites using flow chemistry and photocatalytic application Sha Tao, Mei Yang, Huihui Chen, Shuainan Zhao, and Guangwen Chen Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b05263 • Publication Date (Web): 19 Feb 2018 Downloaded from http://pubs.acs.org on February 19, 2018

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Industrial & Engineering Chemistry Research

Continuous synthesis of Ag/AgCl/ZnO composites using flow chemistry and photocatalytic application Sha Taoa, b, Mei Yanga,*, Huihui Chena,b, Shuainan Zhaoa,b, Guangwen Chena,* a

Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese

Academy of Sciences, Dalian 116023, China b

University of Chinese Academy of Sciences, Beijing 100049, China

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ABSTRACT Ag/AgCl/ZnO composites were successfully synthesized in a continuous microfluidic system under visible light irradiation, which was employed to in situ reduce a portion of AgCl to metallic Ag. The formation of Ag/AgCl/ZnO composites was confined in small aqueous plugs, which were dispersed by octane as the continuous phase. In this way, enhanced mixing, low risk of channel clogging and uniform light distribution were achieved. The characterization results revealed that the as-prepared Ag/AgCl/ZnO composites were composed of flower-like ZnO with Ag/AgCl nanospheres anchored to them. It was found that the synthesis parameters such as water/oil volume flow ratio, total volume flow rate, temperature and the molar ratio of Zn2+ to Ag+ had effects on the synthesis of Ag/AgCl/ZnO composites. Furthermore, the as-prepared Ag/AgCl/ZnO composites outperformed Ag/ZnO composites and AgCl/ZnO composites in the visible light-driven degradation of methyl orange.

KEYWORDS microreactor; microchannel; plasmonic; photocatalyst; photodegradation

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Industrial & Engineering Chemistry Research

1. Introduction

The past decades have witnessed an explosive growth in the development of semiconductor-based photocatalysts for the photodegradation of organic contaminations because of the growing concern about energy and environmental problems. Among the various semiconductor-based photocatalysts, ZnO with a direct wide band gap (3.3 eV) has attracted increasing attention due to its high activity, low cost, abundant resource and nontoxicity, etc.1-4 Unfortunately, the photon-induced electron-hole pairs on the surface of ZnO are liable to recombine quickly, resulting in a decrease in the photocatalytic activity. In addition, the efficiency of sunlight utilization over ZnO is poor since it can be merely excited by UV light (λ