Tuning the d-Band States of Ni-Based Serpentine Materials via Fe3+ Doping for Efficient Oxygen Evolution Reaction

Dingzhong Luo; Baopeng Yang; Zongwei Mei; Qing Kang; Gen Chen; Xiaohe Liu; Ning Zhang

doi:10.1021/acsami.2c14720

Tuning the d-Band States of Ni-Based Serpentine Materials via Fe³⁺ Doping for Efficient Oxygen Evolution Reaction

ACS Appl Mater Interfaces. 2022 Nov 30;14(47):52857-52867. doi: 10.1021/acsami.2c14720. Epub 2022 Nov 16.

Authors

Dingzhong Luo¹, Baopeng Yang^{1

2}, Zongwei Mei³, Qing Kang⁴, Gen Chen¹, Xiaohe Liu⁵, Ning Zhang¹

Affiliations

¹ School of Materials Science and Engineering, Central South University, Changsha 410083, China.
² School of Physics and Electronics, Central South University, Changsha 410083, China.
³ Yangtze Delta Region Institute (Huzhou) & School of Physics, University of Electronic Science and Technology of China, Huzhou 313001, China.
⁴ Institute of Surface Analysis and Chemical Biology, University of Jinan, Jinan 250022, China.
⁵ School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China.

PMID: 36383731
DOI: 10.1021/acsami.2c14720

Abstract

The serpentine germanate materials are promising oxygen evolution reaction (OER) electrocatalysts due to their unique layered crystal structure and electronic structure. However, the catalytic activities still need to be improved to satisfy the practical applications. Adjusting the d-band center of metal active site to balance the adsorption and desorption of intermediates is considered an effective approach to improve the OER activity. In this work, an element dopant strategy was proposed to optimize the d-band state of Ni₃Ge₂O₅(OH)₄ serpentine to improve the OER activity. The density functional theory calculations revealed that Fe³⁺ doping increased the d-band center of the Ni₃Ge₂O₅(OH)₄ serpentine, which optimized the adsorption strength of intermediates on surface Ni and Fe atoms so that the Fe³⁺ doped Ni₃Ge₂O₅(OH)₄ (Ni_2.25Fe_0.75Ge₂O₅(OH)₄) exhibited much reduced Gibbs free energy changes in the rate-determining step compared with pristine serpentine. Inspired by the theoretical calculations, the Ni_xFe_3-xGe₂O₅(OH)₄ nanosheets with different amounts of doped Fe³⁺ were designed and synthesized. The structural characterizations indicated that Fe³⁺ was successfully doped into Ni₃Ge₂O₅(OH)₄ and replaced the Ni²⁺. The Fe³⁺ doped Ni_xFe_3-xGe₂O₅(OH)₄ nanosheets showed greatly improved OER activity than Ni₃Ge₂O₅(OH)₄ and Fe₃Ge₂O₅(OH)₄. Further electrochemical analysis illustrated that Fe³⁺ doping reduced the adsorptive/formative resistance of intermediates and the charge transfer resistance and facilitated the kinetic process of OER. The in situ Raman spectra indicated that the Fe³⁺ doped Ni₃Ge₂O₅(OH)₄ possesses a more active Ni-O bond than pristine Ni₃Ge₂O₅(OH)₄. This work provides an effective strategy to tune the d-band center of serpentines for efficient electrocatalytic OER.

Keywords: DFT calculations; d-band center; electrocatalysis; oxygen evolution reaction; serpentine.