Multi-interfacial Plasmon Coupling in Multigap (Au/AgAu)@CdS Core-Shell Hybrids for Efficient Photocatalytic Hydrogen Generation
Plasmon coupling induced intense light absorption and near-field enhancement have vast potential for high-efficiency photocatalytic application. Herein, (Au/AgAu)@CdS core-shell hybrids with strong multi-interfacial plasmon coupling were prepared through a convenient strategy for efficient photocatalytic hydrogen generation. Bimetallic Au/AgAu cores with adjustable number of nanogaps (from one to four) were primarily synthesized by well-controlled multi-cycle galvanic replacement and overgrowth processes. Extinction tests and numerical simulations synergistically revealed that the multigap Au/AgAu hybrids possess gap-depended light absorption region and local electric field owing to the multigap-induced multi-interfacial plasmon coupling. With these characters, hetero-photocatalysts by further coating of CdS shells on multigap Au/AgAu cores exhibited prominent gap-depended photocatalytic hydrogen production activity from water splitting under light irradiation (λ > 420 nm). It’s found that the hydrogen generation rates of multigap (Au/AgAu)@CdS have an exponential improvement compared with pure CdS as the number of nanogaps increased. Specially, four-gap (Au/AgAu)@CdS core-shell catalyst displayed the highest hydrogen generation rate, that is 96.1 and 47.2 times of pure CdS and gapless Au@CdS core-shell hybrids. These improvements can be ascribed to the strong plasmon absorption and near-field enhancement induced by the multi-interfacial plasmon coupling, which can greatly improve the light-harvesting efficiency, offer more plasmonic energy, boost the generation and separation of electron-hole pairs in the multigap catalysts.