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论文类型：期刊论文

发表时间：2017-02-01

发表刊物：CHEMICAL ENGINEERING JOURNAL

收录刊物：SCIE、EI、ESI高被引论文

卷号：309

页面范围：426-434

ISSN号：1385-8947

关键字：NiCo2O4 hollow microspheres; Tunable structures; Supercapacitors

摘要：We report a new resin formaldehyde (RF-COOH) microspheres hard templates based method to synthesize NiCo2O4 hollow microspheres with thin/thick single/double/triple-shell. Single-shell NiCo2O4 hollow microspheres are obtained with deionized water as solvent. Furthermore, ethylene glycol can decrease the aquo groups (H2O) number within the coordination sphere of Ni2+/Co2+, which leads to a decrease of hydrated metal ions size and more penetrated metal ions into RF microspheres that is essential to the formation of more shells. Thus, double and triple-shell NiCo2O4 hollow microspheres are harvested when ethylene glycol is solvent and the heating ramp rate are 2 and 5 degrees C/min, respectively. Larger heating ramp rate (2-5 degrees C/min) increases the temperature gradient of the infused RF microspheres, which favors the separation between adjacent NiCo2O4 layers and RF cores, and thus resulting in the formation of more shells. What's more, shells become thick and more compact when the precursor concentration is increased from 0.05 to 0.1 M due to more infused Ni2+/Co2+. The electrochemical performance for super capacitors of NiCo2O4 hollow microspheres with thin multi-shells is superior to those with thick single shell. The better performances are attributed to multi-shells with more electroactive sites and hollow structures as "ion-buffering reservoir", while thin shell is beneficial to the diffusion of electrolyte/ions. (C) 2016 Published by Elsevier B.V.