Enhancing hot-electron generation and transfer from metal to semiconductor in a plasmonic absorber

Plasmon-induced hot electron transfer in metal/semiconductor hybrid structure is of vital importance for various photochemistry applications due to its unique ability to harvest light energy, but the enhancement ability is generally weak in traditional hybrid structures because of low yield of hot electrons and low electron utilization rate. The trade-off between absorption and charge collection is one of the critical challenges to overcome for enhancing the hot electron generation and transfer. Herein, by combining the localized surface plasmon resonance (LSPR) with resonant light trapping, we demonstrate an effective route to design excellent plasmonic absorbers based on metal-semiconductor core-shell nanoparticles (NPs) and metal film. The designed plasmonic absorber Au@Cu2O-Au exhibits an intensively enhanced absorption ( > 90%) in the whole visible range due to the strong destructive interference of partial reflected light by the synergistic effect of the thin absorptive NPs layer and Au film. As corroborated by the transient absorption measurements, except for increase of the hot electron generation, the introduction of plasmonic NPs and Au film can improve greatly the photoelectrochemical performance thanks to the effective triple-channel hot electron transfer pathways. Such a plasmonic absorber can provide an excellent platform for solar energy conversion and paves the way for designing photoelectrochemical cells and various absorptive devices for photovoltaics and photodetection.