Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (12): 1970-1980.DOI: 10.1016/S1872-2067(17)62965-6

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Improved visible-light photocatalytic H2 generation over CdS nanosheets decorated by NiS2 and metallic carbon black as dual earth-abundant cocatalysts

Song Maa, Xingmin Xua, Jun Xiea,b, Xin Lia,b   

  1. a College of Materials and Energy, South China Agricultural University, Guangzhou 510642, Guangdong, China;
    b College of Forestry and Landscape Architecture, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China
  • Received:2017-10-09 Revised:2017-10-31 Online:2017-12-18 Published:2017-12-29
  • Supported by:

    The work was supported by the National Natural Science Foundation of China (51672089), the Science and Technology Planning Project of Guangdong Province (2015B020215011), and the State Key Laboratory of Advanced Technology for Material Synthesis and Processing (Wuhan University of Technology) (2015-KF-7).

Abstract:

CdS nanosheets (NSs) photocatalysts modified with dual earth-abundant co-catalysts of metallic carbon black (CB) and NiS2 were synthesized by a two-step solvother-mal/impregnation method. All the experiment results demonstrated that the co-loading of CB and NiS2 could significantly enhance the photocatalytic H2-evolution activity of CdS NSs. The photocatalytic performance of the as-prepared CdS/CB/NiS2 samples was tested under visible light (λ ≥ 420 nm) by using an aqueous solution containing 0.25 mol L-1 Na2S-Na2SO3 as the sacrifice agent. The CdS-0.5% CB-1.0%NiS2 composite photocatalysts exhibited the highest H2-evolution rate of 166.7 μmol h-1, which was approximately 5.16 and 1.87 times higher than those of pure CdS NSs and CdS-1.0%NiS2, respectively. The possible mechanism for the enhanced H2-evolution activity of CdS/CB/NiS2 composite photocatalysts was proposed. The results showed that the enhanced photocatalytic H2-evolution activities could be ascribed to the co-loading of metallic CB and NiS2 as co-catalysts onto the surface of CdS NSs. The excellent synergetic effect between the CB and NiS2 could obviously improve visible light absorption, promote separation of photogenerated electron-hole pairs and boost the H2-evolution kinetics, thus leading to an enhanced activity for H2 evolution. More interestingly, the metallic CB could not only act as a cocatalyst for H2 evolution, but also serve as a conductive electron bridge to promote the charge migration. This work not only demonstrates that loading CB as a co-catalyst is a promising strategy to further boost the photocatalytic activity of CdS/NiS2 composites, but also offers a new mechanistic insight into the construction of highly efficient and stable CdS NSs-based hybrid photocatalysts with dual earth-abundant co-catalysts for photocatalytic applications.

Key words: Photocatalytic hydrogen evolution, CdS nanosheet, Carbon black, NiS2, Dual co-catalyst