Insight into the Effect of Highly Dispersed MoS2 versus Layer-Structured MoS2 on the Photocorrosion and Photoactivity of CdS in Graphene–CdS–MoS2 Composites

Designing a semiconductor CdS-based photocatalyst for H 2 evolution from water with high activity and stability is extremely desirable for practical application. We report the important morphological and structural influence of MoS 2 cocatalyst on the photocorrosion and photoactivity of CdS that is carpeted on a graphene (GR) surface. Homogeneous dispersion of MoS 2 nanoparticles by a controlled photodeposition (PD) method produces the GR–CdS–MoS 2 (PD) composite, which does not have the characteristic stacked layer structure of MoS 2 . However, this GR–CdS–MoS 2 (PD) composite exhibits much higher activity and particularly antiphotocorrosion than the hydrothermal synthesized GR–CdS–MoS 2 (HT) counterparts, which feature the characteristic MoS 2 layer structure, toward photocatalytic water splitting under visible light irradiation. The characterization results indicate that homogeneous dispersion of tiny MoS 2 for GR–CdS–MoS 2 (PD) markedly improves the separation and transfer of charge carriers and provides the increased number of catalytic active sites afforded by the absence of the stacked layer structure of the MoS 2 cocatalyst. This work provides direct evidence of the negative effect of the stacked layer structure of MoS 2 on boosting the activity and photostability of CdS on the GR surface, which would guide the more rational use of MoS 2 and GR as cocatalyst toward achieving a highly active and stable semiconductor-based composite photocatalyst for H 2 evolution.