Effects of Interfaces and Growth Sites on the Extraction Efficiency of Plasmonic Hot Electrons in Photocatalysis

The efficiencies of plasmonic hot-electron-based materials or devices are determined by the transfer efficiency of hot electrons from plasmonic metals to semiconductors. Since the hot-electron transfer takes place at the interface between plasmonic metals and semiconductors, their interface plays a critical role in the hot-electron efficiency. Herein, Au/CdS and Au/CdSe nanostructures with different morphologies are synthesized to study the morphology and interface effects on the hot-electron efficiency. The end-selectively grown nanostructures, Au/end-CdSe and Au/end-CdSe, show extraction efficiencies of hot electrons higher than those of their corresponding fully coated counterparts. For the nanostructures with the same morphology, the Au/CdSe nanostructures have a much higher hot-electron efficiency than the Au/CdS ones. Theoretical calculations indicate that Au/CdS nanostructures exhibit formidable barriers for hot-electron injection, while Au/CdSe nanostructures show resonant electronic states between two components near the Fermi level and are without barriers for hot-electron injection. These two effects jointly account for the higher hot-electron efficiency of Au/CdSe, regardless of whether a direct or indirect transfer mechanism occurs in Au/CdSe nanostructures. These findings unveil the interfacial and morphology effects on the hot-electron efficiency of plasmonic metal/semiconductor nanostructures and will be helpful in the design of nanostructures with high hot-electron efficiency.