title: Hollow Fluffy Co3O4 Cages as Efficient Electroactive Materials for Supercapacitors and Oxygen Evolution Reaction.
abstract: Nano-/micrometer multiscale hierarchical structures not only provide large surface areas for surface redox reactions but also ensure efficient charge conductivity, which is of benefit for utilization in areas of electrochemical energy conversion and storage. Herein, hollow fluffy cages (HFC) of Co3O4, constructed of ultrathin nanosheets, were synthesized by the formation of Co(OH)2 hollow cages and subsequent calcination at 250 °C. The large surface area (245.5 m2 g(-1)) of HFC Co3O4 annealed at 250 °C ensures the efficient interaction between electrolytes and electroactive components and provides more active sites for the surface redox reactions. The hierarchical structures minimize amount of the grain boundaries and facilitate the charge transfer process. Thin thickness of nanosheets (2-3 nm) ensures the highly active sites for the surface redox reactions. As a consequence, HFC Co3O4 as the supercapacitor electrode exhibits a superior rate capability, shows an excellent cycliability of 10,000 cycles at 10 A g(-1), and delivers large specific capacitances of 948.9 and 536.8 F g(-1) at 1 and 40 A g(-1), respectively. Catalytic studies of HFC Co3O4 for oxygen evolution reaction display a much higher turnover frequency of 1.67×10(-2) s(-1) in pH 14.0 KOH electrolyte at 400 mV overpotential and a lower Tafel slope of 70 mV dec(-1). HFC Co3O4 with the efficient electrochemical activity and good stability can remain a promising candidate for the electrochemical energy conversion and storage.
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Xuemei
authors: X
authors: Zhou
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Xuetao
authors: X
authors: Shen
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Zhaoming
authors: Z
authors: Xia
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Zhiyun
authors: Z
authors: Zhang
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Jing
authors: J
authors: Li
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Yuanyuan
authors: Y
authors: Ma
authors: Center for Applied Chemical Research, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University and ‡MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University , Xi'an 710049, China.
authors: Yongquan
authors: Y
authors: Qu
keywords: electrochemical capacitance; hierarchical structures; hollow cages Co3O4; oxygen evolution reaction; ultrathin nanosheets