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

Incorporation of plasmonic metal nanomaterials can significantlyenhance the visible light response of semiconductor photocatalystsvia localized surface plasmon resonance (LSPR) mechanisms. However,the surfaces of plasmonic metal nanomaterials are often covered withsurfactant molecules, which is undesired when the nanomaterials areused for photocatalytic hydrogen evolution, since surfactant moleculescould significantly compromise the nanomaterials' cocatalystfunctionalities by blocking the active sites and/or by inhibitingthe surface charge transfer process. Herein, we demonstrate a methodthat assembles Au nanoparticles (NPs) into Au colloidosomes (AuCSs)without modifying their surfaces with surfactants. The resulting AuCSswere then coupled with CdS for the formation of Au-CdS compositephotocatalysts through an in situ deposition method.The assembly of Au NPs induced a broader and stronger LSPR responsefor AuCSs, while the absence of surfactants allowed them to act efficientlyas cocatalysts. This essentially enhanced the electron-holepair generation rate and further their utilization efficiency, leadingto an extremely high hydrogen evolution rate of 235.8 mmol center dot g(-1)center dot h(-1) under simulated sunlightexcitation.