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Self‐Assembled α‐Fe 2 O 3 Mesocrystals/Graphene Nanohybrid for Enhanced Electrochemical Capacitors
Author(s) -
Yang Shuhua,
Song Xuefeng,
Zhang Peng,
Sun Jing,
Gao Lian
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201303922
Subject(s) - graphene , materials science , nanotechnology , electrochemistry , nanorod , electrode , electrolyte , supercapacitor , chemical engineering , capacitance , conductivity , chemistry , engineering
Self‐assembled α‐Fe 2 O 3 mesocrystals/graphene nanohybrids have been successfully synthesized and have a unique mesocrystal porous structure, a large specific surface area, and high conductivity. Mesocrystal structures have recently attracted unparalleled attention owing to their promising application in energy storage as electrochemical capacitors. However, mesocrystal/graphene nanohybrids and their growth mechanism have not been clearly investigated. Here we show a facile fabrication of short rod‐like α‐Fe 2 O 3 mesocrystals/graphene nanohybrids by self‐assembly of FeOOH nanorods as the primary building blocks on graphene under hydrothermal conditions, accompanied and promoted by concomitant phase transition from FeOOH to α‐Fe 2 O 3 . A systematic study of the formation mechanism is also presented. The galvanostatic charge/discharge curve shows a superior specific capacitance of the as‐prepared α‐Fe 2 O 3 mesocrystals/graphene nanohybrid (based on total mass of active materials), which is 306.9 F g −1 at 3 A g −1 in the aqueous electrolyte under voltage ranges of up to 1 V. The nanohybrid with unique sufficient porous structure and high electrical conductivity allows for effective ion and charge transport in the whole electrode. Even at a high discharge current density of 10 A g −1 , the enhanced ion and charge transport still yields a higher capacitance (98.2 F g −1 ), exhibiting enhanced rate capability. The α‐Fe 2 O 3 mesocrystal/graphene nanohybrid electrode also demonstrates excellent cyclic performance, which is superior to previously reported graphene‐based hematite electrode, suggesting it is highly stable as an electrochemical capacitor.