Hollow Fluffy Co3O4 Cages as Efficient Electroactive Materials for Supercapacitors and Oxygen Evolution Reaction.
Hollow Fluffy Co3O4 Cages as Efficient Electroactive Materials for Supercapacitors and Oxygen Evolution Reaction.
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DOI：
10.1021/acsami.5b05989
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发表时间：
2015-09
影响因子：
9.5
通讯作者：
Xuemei Zhou;Xuetao Shen;Zhaoming Xia;Zhiyun Zhang;Jing Li;Yuanyuan Ma;Y. Qu
中科院分区：
文献类型：
--
作者：
Xuemei Zhou;Xuetao Shen;Zhaoming Xia;Zhiyun Zhang;Jing Li;Yuanyuan Ma;Y. Qu
纳米/微米多尺度分级结构不仅为表面氧化还原反应提供了大的表面积，而且还确保了有效的电荷导电性，这有利于在电化学能量转换和存储领域中的利用。本文中，通过形成Co（OH）2中空笼并随后在250 °C下煅烧来合成由纳米片构成的Co 3 O 4的中空蓬松笼（HFC）。在250 °C下退火的HFC Co 3 O 4的大表面积（245.5 m2 g（-1））确保了电解质和电活性组分之间的有效相互作用，并为表面氧化还原反应提供了更多的活性位点。分层结构使晶界的数量最小化并促进电荷转移过程。纳米片的薄厚度（2-3 nm）确保了表面氧化还原反应的高活性位点。因此，作为超级电容器电极的HFC Co 3 O 4表现出上级倍率性能，显示出在10 A g（-1）下10，000次循环的优异循环性，并在1和40 A g（-1）下分别提供948.9和536.8 F g（-1）的大比电容。对HFC Co 3 O 4析氧反应的催化研究显示，在pH 14.0的KOH电解液中，在400 mV的过电位下，转换频率要高得多，为1.67×10（-2）s（-1），塔菲尔斜率较低，为70 mV dec（-1）。HFC Co 3 O 4具有高效的电化学活性和良好的稳定性，是一种很有前途的电化学能量转换和储存材料。
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.