Elsevier

Applied Surface Science

Volume 358, Part A, 15 December 2015, Pages 146-151
Applied Surface Science

One-pot self-assembly of Cu2O/RGO composite aerogel for aqueous photocatalysis

https://doi.org/10.1016/j.apsusc.2015.08.021Get rights and content

Highlights

  • Cu2O/RGO aerogel was prepared hydrothermally using glucose as a reducing agent and cross-linker.

  • Cu2O/RGO aerogel showed superior performance for photocatalytic degradation of MO.

  • Cu2O/RGO aerogel can be facilely separated from the reaction systems for recycling.

Abstract

Cu2O/reduced graphene oxide (RGO) composite aerogel was fabricated by a one-pot hydrothermal method using glucose as a reducing agent and cross-linker. The as-obtained Cu2O/RGO composite aerogel showed superior photocatalytic activity for MO degradation owing to its improved light absorption capability, enhanced adsorption toward pollutant and the RGO promoted charge carrier separation. The Cu2O/RGO composite aerogel can also be facilely separated from the reaction system for recycling, which makes it especially appealing for using as a visible light responsive photocatalyst in aqueous photocatalysis.

Graphical abstract

Schematic formation process of Cu2O/RGO aerogel and its recycling processes.

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Introduction

Semiconductor-based photocatalysis has been widely employed in the treatment of various environmental pollutants [1], [2], [3], [4], [5]. The incorporation of reduced graphene oxide (RGO) into semiconductor photocatalysts has been proved to be an effective strategy to improve their performance [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]. The existence of suitable amount of functional groups on RGO surface ensures RGO to have intimate contact with the semiconductor photocatalysts, which helps to promote the separation of the photo-generated charge carriers in semiconductors [18]. However, the use of these RGO–semiconductor nanocomposites in aqueous photocatalytic systems meets with limitation since these powder materials are difficult to be separated from the reaction system [19], [20], [21], [22]. For practical applications, it is ideal to immobilize the nano-structured photocatalysts on certain solid surfaces for separation and recycling.

Recently, reduced graphene oxide (RGO)-based aerogels have attracted extensive attention and have shown a variety of applications due to their peculiar properties, including low density, high surface area, large open pores, as well as those translated from the RGO building block [23], [24], [25], [26], [27]. Our recent studies also demonstrated that RGO-based aerogel can be an ideal support for semiconductor photocatalysts due to its large specific surface area for enhanced adsorption toward pollutants, open pores for fast mass transportation, easy tuning of surface wettability for selective adsorption toward pollutants [28], [29], [30]. The most attractive of using RGO aerogels as support for photocatalysts lies in its extremely light weight, which enables it to float on the surface of the reaction system to absorb more solar irradiations [28], [29]. However, although RGO incorporated semiconductor photocatalysts have been well studied, the investigations on the formation of semiconductor/RGO composite aerogels with focus on their applications in photocatalysis is limited [28], [29].

Herein, we reported a facile one-pot hydrothermal method to synthesize Cu2O/RGO composite aerogel using glucose as a reducing agent and cross-linker. Cu2O, a p-type semiconductor with a band-gap of about 2.0 eV, has been used in water purification due to its appropriate band gap, non-toxicity and environmental compatibility [31], [32], [33]. By embedding Cu2O into RGO aerogel, the as-formed Cu2O/RGO composite aerogel shows excellent performance in the photocatalytic degradation of methyl orange (MO) under visible light. The photocatalyst can float on water, showing impressive performance in terms of its activity and stability and due to its macroscopic shape, it is capable of removing it with a tweezers and reusing it with unvaried performance.

Section snippets

Preparation

Graphene oxide (GO) was synthesized using a modified Hummers methods from graphite flake [34].

For preparation of Cu2O/RGO composite aerogel, GO aqueous dispersion (16.7 mL, 6 mg/mL) was sonicated in a 100 mL beaker for 1 h. Then 40 mL CuSO4·5H2O solution containing varied amount of CuSO4·5H2O (200, 400 and 600 mg) was added into GO aqueous dispersion under vigorous magnetic stirring. The pH value of the solution was adjusted to 10. After that, glucose (200 mg) was added under vigorous stirring. The

Results and discussion

The Cu2O/RGO aerogels were prepared from GO and CuSO4·5H2O hydrothermally using glucose as both reducing and cross-linking agent. Since our previous study on the formation of RGO aerogels revealed that RGO hydrogels can be obtained at a weight ratio of GO to reducing agent at 1:2 [28], the weight ratio of GO to glucose was set at 1:2, while the examined weight ratio of GO to CuSO4·5H2O (rG/C) ranged from 1:2 to 1:6. It was found that Cu2O/RGO hydrogels in a 3D cylindrical morphology in the

Conclusions

In summary, Cu2O/RGO composite aerogel was prepared by a facile one-pot hydrothermal method using glucose as reducing agent and cross-linker. The as-formed Cu2O/RGO composite aerogel shows superior photocatalytic performance in the degradation of MO under visible light due to its improved adsorption toward pollutants, enhanced light absorption ascribed to its lightweight as well as the promoted photo-generated charge separation by RGO. The aerogel can be easily separated from the aqueous

Acknowledgements

This work was supported by 973 Program (2014CB239303), NSFC (21273035), Specialized Research Fund for the Doctoral Program of Higher Education (20123514110002) and Independent Research Project of State Key Laboratory of Photocatalysis on Energy and Environment (No. 2014A03). Z. Li thanks the Award Program for Minjiang Scholar Professorship for financial support.

References (40)

  • A. Wang et al.

    Preparation and characterizations of Cu2O/reduced graphene oxide nanocomposites with high photo-catalytic performances

    Powder Technol.

    (2014)
  • H. Tong et al.

    Nano-photocatalytic materials: possibilities and challenges

    Adv. Mater.

    (2012)
  • C.C. Chen et al.

    Semiconductor-mediated photodegradation of pollutants under visible-light irradiation

    Chem. Soc. Rev.

    (2010)
  • W.G. Tu et al.

    Versatile graphene-promoting photocatalytic performance of semiconductors: basic principles, synthesis, solar energy conversion, and environmental applications

    Adv. Funct. Mater.

    (2013)
  • Q.J. Xiang et al.

    Synergetic effect of MoS2 and graphene as cocatalysts for enhanced photocatalytic H2 production activity of TiO2 nanoparticles

    J. Am. Chem. Soc.

    (2012)
  • X.Q. An et al.

    Graphene-based photocatalytic composites

    RSC Adv.

    (2011)
  • Q.J. Xiang et al.

    Graphene-based semiconductor photocatalysts

    Chem. Soc. Rev.

    (2012)
  • T. Meyer et al.

    Advanced charge utilization from NaTaO3 photocatalysts by multilayer reduced graphene oxide

    Chem. Mater.

    (2014)
  • M.Q. Yang et al.

    Artificial photosynthesis over graphene-semiconductor composites. Are we getting better?

    Chem. Soc. Rev.

    (2014)
  • J.C. Liu et al.

    Self-assembling TiO2 nanorods on large graphene oxide sheets at a two-phase interface and their anti-recombination in photocatalytic applications

    Adv. Funct. Mater.

    (2010)
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