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

Abstract 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 ₂ /Cu ₂ S heterostructure is prepared, comprising CdS nanorods (NRs) interfaced with MoS ₂ nanosheets at both ends and Cu ₂ S nanoparticles on the sidewall. By using transient absorption (TA) spectra, highly efficient charge separation within the CdS/MoS ₂ /Cu ₂ S heterostructure are identified. This is achieved through directed electron transfer to the MoS ₂ tips at a rate constant of >8.3 × 10 ⁹ s ⁻¹ and rapid hole transfer to the Cu ₂ S nanoparticles on the sidewall at a rate of >6.1 × 10 ¹⁰ s ⁻¹ , leading to an exceptional overall charge transfer constant of 2.3 × 10 ¹¹ s ⁻¹ in CdS/MoS ₂ /Cu ₂ S. The enhanced hole transfer efficiency results in a remarkably prolonged charge‐separated state, facilitating efficient electron accumulation within the MoS ₂ tips. Consequently, the ternary CdS/MoS ₂ /Cu ₂ S heterostructure demonstrates a 22‐fold enhancement in visible‐light‐driven H ₂ generation compare to pure CdS nanorods. This work highlights the significance of efficient hole extraction in enhancing the solar‐to‐H ₂ performance of semiconductor‐based heterostructure.