Tunable Photodeposition of MoS2 onto a Composite of Reduced Graphene Oxide and CdS for Synergic Photocatalytic Hydrogen Generation

Recently, MoS2 as an excellent cocatalyst for hydrogen evolution reaction (HER) has attracted extensive attention. In this work, MoS2 was controllably loaded on the composite of reduced graphene oxide (rGO) and CdS (rGO/CdS) by a facile photoreduction method at different pHs. At low pH 7, MoS2 deposits on the surface of the CdS particles of the composite. However, at high pH 11, it loads on the exposed rGO. When MoS2 is on the rGO, the transfer of the photoexcited electron from CdS to rGO is compatible with the HER at MoS2 (synergic effect), whereas the transfer is incompatible with the HER when it is on the CdS (antisynergic effect). Moreover, the MoS2 deposited on the CdS decreases the photoabsorption and photoactivity of CdS, and the effect is avoided when MoS2 is on the rGO. The photocatalytic HER rate under the synergic condition is 4.3 times as high as that under antisynergic condition. This work would open a promising way to design and fabricate the efficient composite photocatalysts.