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Roles of MoS 2 and Graphene as Cocatalysts in the Enhanced Visible‐Light Photocatalytic H 2 Production Activity of Multiarmed CdS Nanorods

2015; Wiley; Volume: 7; Issue: 6 Linguagem: Inglês

10.1002/cctc.201403062

1867-3899

Di Lang, Tingting Shen, Quanjun Xiang,

Copper-based nanomaterials and applications

Abstract The incorporation of cocatalysts into semiconductors is proved to be an effective approach to improving the efficiency of the photocatalytic H 2 production. Noble metals such as Pt have been widely used as cocatalysts and can significantly improve the performance of photocatalytic H 2 production. However, owing to the high cost and low abundance, the use of Pt in practical applications is restricted. Herein, we report two well‐known 2 D layered materials, MoS 2 and graphene, as highly active cocatalysts for H 2 production in CdS‐based photocatalytic systems. The CdS–MoS 2 and CdS‐MoS 2 –graphene nanocomposites were prepared by using a facile two‐step solvothermal method, and the morphologies of CdS and MoS 2 can be well controlled. The as‐prepared binary CdS–MoS 2 nanocomposite exhibits the enhanced visible‐light photocatalytic activity for H 2 production in lactic acid aqueous solution compared with a CdS–graphene nanocomposite and a conventional platinized CdS photocatalyst. Moreover, the ternary CdS–MoS 2 –graphene nanocomposite achieves the highest visible‐light photocatalytic H 2 production activity of 621.3 μmol h −1 and the apparent quantum efficiency of 54.4 % at λ =420 nm. The enhanced photocatalytic activity of the CdS–MoS 2 –graphene nanocomposite can be primarily attributed to the positive synergistic effect between graphene sheets and thin MoS 2 nanoplates. The graphene sheets can accelerate the efficient electron transfer from CdS nanorods to the active edge sites of MoS 2 nanoplates, and the nanosized MoS 2 can facilitate the photogenerated electrons participating in the photocatalytic H 2 production. The mechanisms for improving the photocatalytic performance of the MoS 2 ‐ and/or graphene‐modified CdS nanocomposites were proposed by using the electrochemical analysis and photoluminescence measurement.