Hollow Fluffy Co3O4 Cages as Efficient Electroactive Materials for Supercapacitors and Oxygen Evolution Reaction

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• 作者：Xuemei Zhou ; Xuetao Shen ; Zhaoming Xia ; Zhiyun Zhang ; Jing Li ; Yuanyuan Ma ; Yongquan Qu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 16, 2015
• 年：2015
• 卷：7
• 期：36
• 页码：20322-20331
• 全文大小：484K
• ISSN：1944-8252

文摘

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 掳C. The large surface area (245.5 m² g^鈥?) of HFC Co₃O₄ annealed at 250 掳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鈥? 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鈥?00 cycles at 10 A g^鈥?, and delivers large specific capacitances of 948.9 and 536.8 F g^鈥? at 1 and 40 A g^鈥?, respectively. Catalytic studies of HFC Co₃O₄ for oxygen evolution reaction display a much higher turnover frequency of 1.67 脳 10^鈥? s^鈥? in pH 14.0 KOH electrolyte at 400 mV overpotential and a lower Tafel slope of 70 mV dec^鈥?. HFC Co₃O₄ with the efficient electrochemical activity and good stability can remain a promising candidate for the electrochemical energy conversion and storage.