title: Rationally designed graphene-nanotube 3D architectures with a seamless nodal junction for efficient energy conversion and storage.
abstract: One-dimensional (1D) carbon nanotubes (CNTs) and 2D single-atomic layer graphene have superior thermal, electrical, and mechanical properties. However, these nanomaterials exhibit poor out-of-plane properties due to the weak van der Waals interaction in the transverse direction between graphitic layers. Recent theoretical studies indicate that rationally designed 3D architectures could have desirable out-of-plane properties while maintaining in-plane properties by growing CNTs and graphene into 3D architectures with a seamless nodal junction. However, the experimental realization of seamlessly-bonded architectures remains a challenge. We developed a strategy of creating 3D graphene-CNT hollow fibers with radially aligned CNTs (RACNTs) seamlessly sheathed by a cylindrical graphene layer through a one-step chemical vapor deposition using an anodized aluminum wire template. By controlling the aluminum wire diameter and anodization time, the length of the RACNTs and diameter of the graphene hollow fiber can be tuned, enabling efficient energy conversion and storage. These fibers, with a controllable surface area, meso-/micropores, and superior electrical properties, are excellent electrode materials for all-solid-state wire-shaped supercapacitors with poly(vinyl alcohol)/H2SO4 as the electrolyte and binder, exhibiting a surface-specific capacitance of 89.4 mF/cm(2) and length-specific capacitance up to 23.9 mF/cm, - one to four times the corresponding record-high capacities reported for other fiber-like supercapacitors. Dye-sensitized solar cells, fabricated using the fiber as a counter electrode, showed a power conversion efficiency of 6.8% and outperformed their counterparts with an expensive Pt wire counter electrode by a factor of 2.5. These novel fiber-shaped graphene-RACNT energy conversion and storage devices are so flexible they can be woven into fabrics as power sources.
authors.affiliation: Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. ; Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Xue
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA.
authors.forename: Jianbing
authors.initials: J
authors.lastname: Niu
authors.affiliation: Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA.
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Xia
authors.affiliation: Materials and Manufacturing Directorate, Air Force Research Laboratory, Dayton, OH 45433 USA.
authors.forename: Ajit
authors.initials: A
authors.lastname: Roy
authors.affiliation: Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.affiliation: Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245, USA. ; Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China.
authors.forename: Zhong Lin
authors.initials: ZL
authors.lastname: Wang
authors.affiliation: Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. ; Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Dai
keywords: 3D graphene-nanotube architecture; Graphene; carbon nanotube; chemical vapor deposition (CVD); dye-sensitized solar cell (DSSC); energy conversion; energy storage; seamless nodal junction; supercapacitor