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电化学(中英文) ›› 2021, Vol. 27 ›› Issue (6): 637-645.  doi: 10.13208/j.electrochem.201102

• 论文 • 上一篇    下一篇

纳米多孔阳极氧化铁膜的形成及其形貌演变

曹锦伟, 高楠, 高朝卿, 王晨, 尚胜艳, 王云鹏*(), 马海涛*()   

  1. 大连理工大学材料科学与工程学院,辽宁 大连 116024
  • 收稿日期:2020-11-05 修回日期:2020-12-30 出版日期:2021-12-28 发布日期:2021-01-12
  • 通讯作者: 王云鹏,马海涛 E-mail:yunpengw@dlut.edu.cn;htma@dlut.edu.cn
  • 基金资助:
    国家重点研究发展计划(2017YFA0403804)

Formation and Morphological Evolution of Nanoporous Anodized Iron Oxide Films

Jin-Wei Cao, Nan Gao, Zhao-Qing Gao, Chen Wang, Sheng-Yan Shang, Yun-Peng Wang*(), Hai-Tao Ma*()   

  1. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China
  • Received:2020-11-05 Revised:2020-12-30 Published:2021-12-28 Online:2021-01-12
  • Contact: Yun-Peng Wang,Hai-Tao Ma E-mail:yunpengw@dlut.edu.cn;htma@dlut.edu.cn

摘要:

阳极氧化法制备具有纳米多孔结构的阳极氧化铁膜因其潜在的应用价值而倍受关注。然而,在阳极氧化过程中多孔结构的形成机制至今尚不清楚。本文结合电流密度-电位响应(I-V曲线)及法拉第定律的推导,分析了形成纳米多孔阳极氧化铁膜的过程中阳极电流的组成。结果表明,离子电流(导致离子迁移形成氧化物)和电子电流(导致析出氧气)共同组成阳极电流,并且纳米多孔阳极氧化铁膜的形成与两种电流的占比相关。分段式氧化物之间的空腔以及在阳极氧化初期纳米孔道上覆盖的致密膜,表明氧气泡可能是从氧化膜内部析出。此时,阳离子和阴离子绕过作为模具的氧气泡实现传质,最终导致纳米多孔结构的形成。此外,在阳极氧化铁膜形貌演变过程中,氧气泡不断向外溢出会使表面氧化物被冲破,导致表面孔径不断增大。

关键词: 纳米多孔, 氧化铁, 阳极氧化, 临界电位, 氧气泡

Abstract:

The preparation of iron oxide films with nanoporous structure by anodization has attracted much attention for its potential applications. However, the formation mechanism of porous structure during anodization is still unclear. In this paper, the composition of anodic current during the formation of nanoporous anodized iron oxide film was analyzed in combination with the current density-potential response (I-V curve) and the derivation of Faraday’s law. The results showed that the anodic current consisted of an ionic current (leading to the migration of ions to form oxide) and an electronic current (leading to the oxygen evolution), and the formation of the nanoporous anodized iron oxide film was correlated with the ratio of the two currents. Only when the potential was higher than a certain critical potential (20 V under the present experimental conditions), the ionic current to electronic current could maintain a proper ratio, and the precipitated oxygen promoted the formation of nanoporous structures. Otherwise, the anodized iron oxide film existed in the form of an irregular loose layer or a dense layer. However, at relatively high potential of anodization (e.g. 50 V in this experiment), the electronic current might accounted for a large proportion of the total current, which was not conducive to the increase of nanoporous anodized iron oxide film thickness. In addition, the dense film covered on the nanopore channels at the initial stage of anodization, as well as the cavities between segmented oxides, indicated the possible evolution of oxygen bubbles inside the oxide film. And the cations and anions achieved mass transfer around the oxygen bubbles, leading to the formation of the nanoporous anodized iron oxide film. Further, during the morphologic evolution of the anodized iron oxide film, the pore size of the surface increased with the time of anodization, which may be related to the dissolution of the oxide on the surface by prolonged erosion in the electrolyte and the continuous outward spillage of oxygen bubbles punched out the surface oxide.

Key words: nanoporous, iron oxide, anodization, critical potential, oxygen bubbles