Graphene-based ternary composite photocatalysts with genuine heterostructure constituents have attracted extensive attention in photocatalytic hydrogen evolution. Here we report a new graphene-based ternary composite consisting of CdS nanorods grown on hierarchical layered WS2 /graphene hybrid (WG) as a high-performance photocatalyst for hydrogen evolution under visible light irradiation. The optimal content of layered WG as a co-catalyst in the ternary CdS/WS2 /graphene composites was found to be 4.2 wt %, giving a visible light photocatalytic H2 -production rate of 1842 μmol h(-1) g(-1) with an apparent quantum efficiency of 21.2 % at 420 nm. This high photocatalytic H2 -production activity is due to the deposition of CdS nanorods on layered WS2 /graphene sheets, which can efficiently suppress charge recombination, improve interfacial charge transfer, and provide reduction active sites. The proposed mechanism for the enhanced photocatalytic activity of CdS nanorods modified with hierarchical layered WG was further confirmed by transient photocurrent response. This work shows that a noble-metal-free hierarchical layered WS2 /graphene nanosheets hybrid can be used as an effective co-catalyst for photocatalytic water splitting.
The excellent photocatalytic H2 production activity of Co3O4–CdS nanocomposite was mainly attributed to the formation of p–n heterojunctions between the p-type Co3O4 nanoclusters and n-type CdS nanorods, which could promote the photoinduced charge transfer and separation.
The incorporation of cocatalysts into semiconductors is proved to be an effective approach to improving the efficiency of the photocatalytic H2 production. Noble metals such as Pt have been widely used as cocatalysts and can significantly improve the performance of photocatalytic H2 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, MoS2 and graphene, as highly active cocatalysts for H2 production in CdS‐based photocatalytic systems. The CdS–MoS2 and CdS‐MoS2–graphene nanocomposites were prepared by using a facile two‐step solvothermal method, and the morphologies of CdS and MoS2 can be well controlled. The as‐prepared binary CdS–MoS2 nanocomposite exhibits the enhanced visible‐light photocatalytic activity for H2 production in lactic acid aqueous solution compared with a CdS–graphene nanocomposite and a conventional platinized CdS photocatalyst. Moreover, the ternary CdS–MoS2–graphene nanocomposite achieves the highest visible‐light photocatalytic H2 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–MoS2–graphene nanocomposite can be primarily attributed to the positive synergistic effect between graphene sheets and thin MoS2 nanoplates. The graphene sheets can accelerate the efficient electron transfer from CdS nanorods to the active edge sites of MoS2 nanoplates, and the nanosized MoS2 can facilitate the photogenerated electrons participating in the photocatalytic H2 production. The mechanisms for improving the photocatalytic performance of the MoS2‐ and/or graphene‐modified CdS nanocomposites were proposed by using the electrochemical analysis and photoluminescence measurement.
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