Drastic Layer-Number-Dependent Activity Enhancement in Photocatalytic H2 Evolution over nMoS2/CdS (n ≥ 1) Under Visible Light

• Published in: Advanced energy materials 2015-05, Vol.5 (10), p.n/a
• Main Authors: Chang, Kun, Li, Mu, Wang, Tao, Ouyang, Shuxin, Li, Peng, Liu, Lequan, Ye, Jinhua
• Format: Article
• Language: English
• Subjects: co-catalysts; hydrogen evolution; nanomaterials; single-layer MoS2; visible light
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201402279

Exploiting noble‐metal‐free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. As an efficient cocatalyst in photocatalysis, MoS2 is shown promise as a low‐cost alternative to Pt for hydrogen evolution. Here we report a systematical study on controlled synthesis of MoS2 with layer number ranging from ≈1 to 112 and their activities for photocatalytic H2 evolution over commercial CdS. A drastic increase in photocatalytic H2 evolution is observed with decreasing MoS2 layer number. Particularly for the single‐layer (SL) MoS2, the SL‐MoS2/CdS sample reaches a high H2 generation rate of ≈2.01 × 10−3m h−1 in Na2S–Na2SO3 solutions and ≈2.59 × 10−3m h−1 in lactic acid solutions, corresponding to an apparent quantum efficiency of 30.2% and 38.4% at 420 nm, respectively. In addition to the more exposed edges and unsaturated active S atoms, valence band–XPS and Mott–Schottky plots analysis indicate that the SL MoS2 has the more negative conduction band energy level than the H+/H2 potential, facilitating the hydrogen reduction. The single‐layer MoS2 is shown to exhibit high co‐catalytic activity for photocatalytic hydrogen evolution. Single‐layer‐MoS2/CdS with 2.0 wt% of co‐catalyst exhibits the highest H2 generation rate, corresponding to an apparent quantum efficiency of 30.2% in Na2S–Na2SO3 and 38.4% in lactic acid solution at 420 nm.