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Nano Research

Article Title

Synthesis of porous NiO nanocrystals with controllable surface area and their application as supercapacitor electrodes

Authors

Xiaojun Zhang, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China
Wenhui Shi, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Jixin Zhu, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Weiyun Zhao, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Jan Ma, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Subodh Mhaisalkar, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore Energy Research Institute, Nanyang Technological University, 637459, Singapore
Tuti Lim Maria, School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore School of Life Sciences and Chemical Technology, Ngee Ann Polytechnic, 535 Clementi Road, Singapore
Yanhui Yang, School of Chemical and Biomolecular Engineering, Nanyang Technological University, 637459, Singapore
Hua Zhang, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Huey Hoon Hng, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore
Qingyu Yan, School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore Energy Research Institute, Nanyang Technological University, 637459, Singapore

Keywords

Ni(OH)2, NiO, porous nanocrystals, supercapacitor

Abstract

We report a facile way to grow various porous NiO nanostructures including nanoslices, nanoplates, and nanocolumns, which show a structure-dependence in their specific charge capacitances. The formation of controllable porosity is due to the dehydration and re-crystallization of β-Ni(OH)2 nanoplates synthesized by a hydrothermal process. Thermogravimetric analysis shows that the decomposition temperature of the β-Ni(OH)2 nanostructures is related to their morphology. In electrochemical tests, the porous NiO nanostructures show stable cycling performance with retention of specific capacitance over 1000 cycles. Interestingly, the formation of nanocolumns by the stacking of β-Ni(OH)2 nanoslices/plates favors the creation of small pores in the NiO nanocrystals obtained after annealing, and the surface area is over five times larger than that of NiO nanoslices and nanoplates. Consequently, the specific capacitance of the porous NiO nanocolumns (390 F/g) is significantly higher than that of the nanoslices (176 F/g) or nanoplates (285 F/g) at a discharge current of 5 A/g. This approach provides a clear illustration of the process–structure–property relationship in nanocrystal synthesis and potentially offers strategies to enhance the performance of supercapacitor electrodes.

Graphical Abstract

Publisher

Tsinghua University Press

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