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

Recently, MoS 2 as an excellent cocatalyst for hydrogen evolution reaction (HER) has attracted extensive attention. In this work, MoS 2 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, MoS 2 deposits on the surface of the CdS particles of the composite. However, at high pH 11, it loads on the exposed rGO. When MoS 2 is on the rGO, the transfer of the photoexcited electron from CdS to rGO is compatible with the HER at MoS 2 (synergic effect), whereas the transfer is incompatible with the HER when it is on the CdS (antisynergic effect). Moreover, the MoS 2 deposited on the CdS decreases the photoabsorption and photoactivity of CdS, and the effect is avoided when MoS 2 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.