Nano-Micro Letters

The Principle of Introducing Halogen Ions Into β-FeOOH: Controlling Electronic Structure and Electrochemical Performance

Dongbin Zhang1, Xuzhao Han1, Xianggui Kong1, *, Fazhi Zhang1, Xiaodong Lei1, *

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Nano-Micro Lett. (2020) 12: 107

First Online: 06 May 2020 (Article)

DOI:10.1007/s40820-020-00440-2

*Corresponding author. E-mail: leixd@mail.buct.edu.cn (X. Lei); kongxg@mail.buct.edu.cn (X. Kong)

 

Abstract

 


Toc

Coordination tuning electronic structure of host materials is a quite effective strategy for activating and improving the intrinsic properties. Herein, halogen anion (X-) incorporating β-FeOOH (β-FeOOH(X), X= F-, Cl- and Br-) was investigated with a spontaneous adsorption process, which realized a great improvement of supercapacitor performances by adjusting the coordination geometry. Experiments coupled with theoretical calculations demonstrated that the change of Fe-O bond length and structural distortion of β-FeOOH, which is rooted in halogen ions embedment, led to the relatively narrow band gap. Because of the strong electronegativity of X-, the Fe element in β-FeOOH(X)s presented the unexpected high valence state (3+δ), which is facilitating to adsorb SO32- species. Consequently, the designed β-FeOOH(X)s exhibited the good electric conductivity and enhanced the contact between electrode and electrolyte. When used as a negative electrode, the β-FeOOH(F) showed the excellent specific capacity of 391.9 F g-1 at 1 A g-1 current density, almost ten folds improvement compared with initial β-FeOOH, with the superior rate capacity and cyclic stability. This combinational design principle of electronic structure and electrochemical performances provides a promising way to develop advanced electrode materials for supercapacitor.


 

Keywords

β-FeOOH; Halogen ion embedment; Tuning electronic structure; Supercapacitor performance

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