Hole Removal Rate Limits Photodriven H2 Generation Efficiency in CdS-Pt and CdSe/CdS-Pt Semiconductor Nanorod鈥揗etal Tip Heterostructures

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• 作者：Kaifeng Wu ; Zheyuan Chen ; Hongjin Lv ; Haiming Zhu ; Craig L Hill ; Tianquan Lian
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：May 28, 2014
• 年：2014
• 卷：136
• 期：21
• 页码：7708-7716
• 全文大小：530K
• 年卷期：v.136,no.21(May 28, 2014)
• ISSN：1520-5126

文摘

Semiconductor鈥搈etal nanoheterostructures, such as CdSe/CdS dot-in-rod nanorods with a Pt tip at one end (or CdSe/CdS-Pt), are promising materials for solar-to-fuel conversion because they allow rational integration of a light absorber, hole acceptor, and electron acceptor or catalyst in an all-inorganic triadic heterostructure as well as systematic control of relative energetics and spatial arrangement of the functional components. To provide design principles of such triadic nanorods, we examined the photocatalytic H₂ generation quantum efficiency and the rates of elementary charge separation and recombination steps of CdSe/CdS-Pt and CdS-Pt nanorods. We showed that the steady-state H₂ generation quantum efficiencies (QEs) depended sensitively on the electron donors and the nanorods. Using ultrafast transient absorption spectroscopy, we determined that the electron transfer efficiencies to the Pt tip were near unity for both CdS and CdSe/CdS nanorods. Hole transfer rates to the electron donor, measured by time-resolved fluorescence decay, were positively correlated with the steady-state H₂ generation QEs. These results suggest that hole transfer is a key efficiency-limiting step. These insights provide possible ways for optimizing the hole transfer step to achieve efficient solar-to-fuel conversion in semiconductor鈥搈etal nanostructures.