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Issue 40, 2018
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MoS2/CQDs obtained by photoreduction for assembly of a ternary MoS2/CQDs/ZnIn2S4 nanocomposite for efficient photocatalytic hydrogen evolution under visible light

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Abstract

MoS2/CQDs (CQDs stands for carbon quantum dots) with a mass ratio of MoS2/CQDs of 1 : 5 were obtained via photoreduction of (NH4)2MoS4 over irradiated CQDs in the presence of methanol as a sacrificial agent. Self-assembly of ZnIn2S4 microspheres on the surface of MoS2/CQDs was realized under microwave conditions to obtain ternary MoS2/CQDs/ZnIn2S4 microspheres. The ternary MoS2/CQDs/ZnIn2S4 nanocomposite shows significantly superior photocatalytic activity for hydrogen evolution to both MoS2/ZnIn2S4 and CQDs/ZnIn2S4, indicating the existence of a synergistic effect of MoS2 and CQDs in promoting the hydrogen evolution. It was proposed that the transfer of the photo-generated electrons from the semiconductor-based photocatalyst (ZnIn2S4) to the hydrogen evolution cocatalyst (MoS2) is promoted by CQDs acting as a mediator in the ternary MoS2/CQDs/ZnIn2S4 nanocomposite. An optimum performance was observed over a 3.0 wt% MoS2/CQDs/ZnIn2S4 nanocomposite in the presence of Na2S/Na2SO3 as a sacrificial agent, where 750 μmol of hydrogen was evolved in 5 h. The optimum apparent quantum efficiency (AQE) was determined to be 25.6% at a wavelength of 420 nm, which is among the highest AQEs ever reported for ZnIn2S4-based systems. This study provides a strategy for developing highly efficient photocatalysts for hydrogen evolution via using CQDs as a bridge to promote charge transfer in nanocomposites.

Graphical abstract: MoS2/CQDs obtained by photoreduction for assembly of a ternary MoS2/CQDs/ZnIn2S4 nanocomposite for efficient photocatalytic hydrogen evolution under visible light

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Publication details

The article was received on 11 Aug 2018, accepted on 17 Sep 2018 and first published on 17 Sep 2018


Article type: Paper
DOI: 10.1039/C8TA07797E
J. Mater. Chem. A, 2018,6, 19735-19742

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    MoS2/CQDs obtained by photoreduction for assembly of a ternary MoS2/CQDs/ZnIn2S4 nanocomposite for efficient photocatalytic hydrogen evolution under visible light

    B. Wang, Z. Deng, X. Fu and Z. Li, J. Mater. Chem. A, 2018, 6, 19735
    DOI: 10.1039/C8TA07797E

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