Achieving Long-Lived Charge Separated State through Ultrafast Interfacial Hole Transfer in Redox Sites-Isolated CdS Nanorods for Enhanced Photocatalysis.

As opposed to natural photosynthesis, a significant challenge in a semiconductor-based photocatalyst is the limited hole extraction efficiency, which adversely affects solar-to-fuel efficiency. Recent studies have demonstrated that photocatalysts featuring spatially isolated dual catalytic oxidation/reduction sites can yield enhanced hole extraction efficiencies. However, the decay dynamics of excited states in such photocatalysts have not been explored. Here a ternary barbell-shaped CdS/MoS/CuS heterostructure is prepared, comprising CdS nanorods (NRs) interfaced with MoS nanosheets at both ends and CuS nanoparticles on the sidewall. By using transient absorption (TA) spectra, highly efficient charge separation within the CdS/MoS/CuS heterostructure are identified. This is achieved through directed electron transfer to the MoS tips at a rate constant of >8.3 × 10 s and rapid hole transfer to the CuS nanoparticles on the sidewall at a rate of >6.1 × 10 s, leading to an exceptional overall charge transfer constant of 2.3 × 10 s in CdS/MoS/CuS. The enhanced hole transfer efficiency results in a remarkably prolonged charge-separated state, facilitating efficient electron accumulation within the MoS tips. Consequently, the ternary CdS/MoS/CuS heterostructure demonstrates a 22-fold enhancement in visible-light-driven H generation compare to pure CdS nanorods. This work highlights the significance of efficient hole extraction in enhancing the solar-to-H performance of semiconductor-based heterostructure.