Rational Synthesis of Au-CdS Composite Photocatalysts for Broad-Spectrum Photocatalytic Hydrogen Evolution.

Incorporation of plasmonic metal nanomaterials can significantly enhance the visible light response of semiconductor photocatalysts via localized surface plasmon resonance (LSPR) mechanisms. However, the surfaces of plasmonic metal nanomaterials are often covered with surfactant molecules, which is undesired when the nanomaterials are used for photocatalytic hydrogen evolution, since surfactant molecules could significantly compromise the nanomaterials' cocatalyst functionalities by blocking the active sites and/or by inhibiting the surface charge transfer process. Herein, we demonstrate a method that assembles Au nanoparticles (NPs) into Au colloidosomes (AuCSs) without modifying their surfaces with surfactants. The resulting AuCSs were then coupled with CdS for the formation of Au-CdS composite photocatalysts through an in situ deposition method. The assembly of Au NPs induced a broader and stronger LSPR response for AuCSs, while the absence of surfactants allowed them to act efficiently as cocatalysts. This essentially enhanced the electron-hole pair generation rate and further their utilization efficiency, leading to an extremely high hydrogen evolution rate of 235.8 mmol·g-1·h-1 under simulated sunlight excitation.