High-quality metal oxide core/shell nanowire arrays on conductive substrates for electrochemical energy storage

• Main Authors: Xia, Xinhui, Tu, Jiangping, Zhang, Yongqi, Wang, Xiuli, Gu, Changdong, Zhao, Xin-bing, Fan, Hong Jin
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2013
• Online Access: https://hdl.handle.net/10356/96509; http://hdl.handle.net/10220/10315
• Institution: Nanyang Technological University

The high performance of a pseudocapacitor electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. We present a powerful two-step solution-based method for the fabrication of transition metal oxide core/shell nanostructure arrays on various conductive substrates. Demonstrated examples include Co3O4 or ZnO nanowire core and NiO nanoflake shells with a hierarchical and porous morphology. The “oriented attachment” and “self-assembly” crystal growth mechanisms are proposed to explain the formation of the NiO nanoflake shell. Supercapacitor electrodes based on the Co3O4/NiO nanowire arrays on 3D macroporous nickel foam are thoroughly characterized. The electrodes exhibit a high specific capacitance of 853 F/g at 2 A/g after 6000 cycles and an excellent cycling stability, owing to the unique porous core/shell nanowire array architecture, and a rational combination of two electrochemically active materials. Our growth approach offers a new technique for the design and synthesis of transition metal oxide or hydroxide hierarchical nanoarrays that are promising for electrochemical energy storage, catalysis, and gas sensing applications.