Lithographically Patterned Gold/Manganese Dioxide Core/Shell Nanowires for High Capacity, High Rate, and High Cyclability Hybrid Electrical Energy Storage
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- 作者：Wenbo Yan ; Jung Yun Kim ; Wendong Xing ; Keith C. Donavan ; Talin Ayvazian ; Reginald M. Penner
- 刊名：Chemistry of Materials
- 出版年：2012
- 出版时间：June 26, 2012
- 年：2012
- 卷：24
- 期：12
- 页码：2382-2390
- 全文大小：569K
- 年卷期：v.24,no.12(June 26, 2012)
- ISSN：1520-5002
文摘
We describe the fabrication of arrays of nanowires on glass in which a gold core nanowire is encapsulated within a hemicylindrical shell of manganese dioxide. Arrays of linear gold (Au) nanowires are first prepared on glass using the lithographically patterned nanowire electrodeposition (LPNE) method. These Au nanowires have a rectangular cross-section with a width and height of 鈮?00 and 40 nm, respectively, and lengths in the 1 mm to 1 cm range. Au nanowires are then used to deposit MnO2 by potentiostatic electrooxidation from Mn2+ solution, forming a conformal, hemicylindrical shell with a controllable diameter ranging from 50 to 300 nm surrounding each Au nanowire. This MnO2 shell is 未-phase and mesoporous, as revealed by X-ray diffraction and Raman spectroscopy. Transmission electron microscopy (TEM) analysis reveals that the MnO2 shell is mesoporous (mp-MnO2), consisting of a network of 鈮? nm fibrils. The specific capacitance, Csp, of arrays of gold:mp-MnO2 nanowires is measured using cyclic voltammetry. For a mp-MnO2 shell thickness of 68 卤 3 nm, core:shell nanowires produce a Csp of 1020 卤 100 F/g at 5 mV/s and 450 卤 70 F/g at 100 mV/s. The cycle stability of this Csp, however, is extremely limited in aqueous electrolyte, decaying by >90% in 100 scans, but after oven drying and immersion in dry 1.0 M LiClO4, acetonitrile, dramatically improved cycle stability is achieved characterized by the absence of Csp fade for 1000 cycles at 100 mV/s. Core:shell nanowires exhibit true hybrid energy storage, as revealed by deconvolution of Csp into insertion and noninsertion components.