Chinese Journal of Catalysis ›› 2021, Vol. 42 ›› Issue (6): 980-993.DOI: 10.1016/S1872-2067(20)63724-X

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Critical roles of molybdate anions in enhancing capacitive and oxygen evolution behaviors of LDH@PANI nanohybrids

Qiang Hua, Hua Wanga, Feifei Xianga, Qiaoji Zhenga, Xinguo Mab, Yu Huoa, Fengyu Xiea, Chenggang Xua, Dunmin Lina,*(), Jisong Hub,#()   

  1. aCollege of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610066, Sichuan, China
    bSchool of Science, Hubei University of Technology, Wuhan 430068, Hubei, China
  • Received:2020-08-17 Accepted:2020-10-09 Online:2021-06-18 Published:2021-01-30
  • Contact: Dunmin Lin,Jisong Hu
  • About author:#E-mail: jisong.hu@yahoo.com
    *Tel/Fax: +86-28-84760802; E-mail: ddmd222@sicnu.edu.cn;
  • Supported by:
    Sichuan Science and Technology Program(2018JY0447)

Abstract:

Low-overpotential layered hydroxides (LDHs) with high theoretical capacity are promising electrodes for supercapaterry and oxygen evolution reaction; however, the low electronic conductivity and insufficient active sites of bulk LDHs increase the internal resistance and reduce the capacity and oxygen-production efficiency of electrodes. Herein, we prepared a polyaniline-coated NiCo-layered double hydroxide intercalated with MoO42- (M-LDH@PANI) composite electrode using a two-step method. As the amount of MoO42- in the LDH increases, acicular microspheres steadily evolve into flaky microspheres with a high surface area, providing more active electrochemical sites. Moreover, the amorphous PANI coating of M-LDH boosts the electronic conductivity of the composite electrode. Accordingly, the M-LDH@PANI at an appropriate level of MoO42- exhibits significantly enhanced energy storage and catalytic performance. Experimental analyses and theoretical calculations reveal that a small amount of MoO42- is conducive to the expansion of LDH interlayer spacing, while an excessive amount of MoO42- combines with the H atoms of LDH, thus competing with OH-, resulting in reduced electrochemical performance. Moreover, M-LDH flaky microspheres can efficiently modulate deprotonation energy, greatly accelerating surface redox reactions. This study provides an explanation for an unconventional mechanism, and a method for the modification of LDH-based materials for anion intercalation.

Key words: Layered hydroxide LDH, PANI, MoO42-, Intercalated hierarchical structures, Supercapaterry, Electrocatalyst