Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 20, Issue 4, Pages 1176-1185Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201303446
Keywords
graphene; hydrothermal synthesis; nanoparticles; photocatalysis; water splitting
Categories
Funding
- 973 program [2013CB632402]
- 863 Program [2012AA062701]
- NSFC [51272199, 51320105001, 51372190, 21177100]
- Fundamental Research Funds for the Central Universities [125101001, 2013-VII-030]
- Self-determined and Innovative Research Funds of SKLWUT [2013-ZD-1]
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In response to the increasing concerns over energy and environmental sustainability, photocatalytic water-splitting technology has attracted broad attention for its application in directly converting solar energy to valuable hydrogen (H-2) energy. In this study, high-efficiency visible-light-driven photocatalytic H-2 production without the assistance of precious-metal cocatalysts was achieved on graphene-ZnxCd1-xS composites with controlled compositions. The graphene-ZnxCd1-xS composites were for the first time fabricated by a one-step hydrothermal method with thiourea as an organic S source. It was found that thiourea facilitates heterogeneous nucleation of ZnxCd1-xS and in situ growth of ZnxCd1-xS nanoparticles on graphene nanosheets. Such a scenario results in abundant and intimate interfacial contact between graphene and ZnxCd1-xS nanoparticles, efficient transfer of the photogenerated charge carriers, and enhanced photocatalytic activity for H-2 production. The highest H-2-production rate of 1.06mmolh(-1)g(-1) was achieved on a graphene-Zn0.5Cd0.5S composite photocatalyst with a graphene content of 0.5wt%, and the apparent quantum efficiency was 19.8% at 420nm. In comparison, the graphene-ZnxCd1-xS composite photocatalyst prepared by using an inorganic S source such as Na2S exhibited much lower activity for photocatalytic H-2 production. In this case, homogeneous nucleation of ZnxCd1-xS becomes predominant and results in insufficient and loose contact with the graphene backbone through weak van der Waals forces and a large particle size. This study highlights the significance of the choice of S source in the design and fabrication of advanced graphene-based sulfide photocatalytic materials with enhanced activity for photocatalytic H-2 production.
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