Construction of alternating layered quasi-three-dimensional electrode Ag NWs/CoO for water splitting: A discussion of catalytic mechanism

It is increasingly important to synthesize a low-cost and high-efficiency bifunctional electrocatalyst for overall water splitting. Herein, a unique line-sphere layered superstructure Ag/CoO is prepared via a facile alternating electrodeposition method. Compared to electrocatalysts with CoO as the i...

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Bibliographic Details
Published in:Electrochimica acta 2019-09, Vol.317, p.468-477
Main Authors: Liu, Xuanwen, Wang, Renchao, He, Yan, Ni, Zhiyuan, Su, Na, Guo, Rui, Zhao, Yao, You, Junhua, Yi, Tingfeng
Format: Article
Language:English
Subjects:
Ag NWs
Catalysis
Catalysts
CoO
Diffusion rate
Electrocatalysts
Electrodes
HER
Hydrogen evolution reactions
Nanowires
OER
Oxygen evolution reactions
Quasi-three-dimensional electrode
Reaction kinetics
Resistance
Silver
Species diffusion
Superstructures
Water splitting
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Summary:It is increasingly important to synthesize a low-cost and high-efficiency bifunctional electrocatalyst for overall water splitting. Herein, a unique line-sphere layered superstructure Ag/CoO is prepared via a facile alternating electrodeposition method. Compared to electrocatalysts with CoO as the innermost layer, the Ag/CoO catalysts with Ag nanowires (NWs) as initial layer take more advantages of the low conductance for water splitting. Electrochemical tests reveal that the layered superstructure material with n+1 layers of Ag NWs and n layers of CoO (An+1Cn) exhibits excellent catalytic activities and stabilities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In addition, when the catalyst consisting of 3 layers of Ag NWs and 2 layers of CoO (A3C2) used as a dual-function electrode, only a potential of 1.90 V is needed for current density of 10 mA cm−2. Based on the kinetics and thermodynamic measurements of the catalytic processes, a reasonable catalytic mechanism of overall water splitting has been proposed for different electrocatalysts. The results show that the diffusion of hydrogen-containing species may be the rate-determining step. [Display omitted] •Ag/CoO electrodes were successfully prepared by alternating electrodeposition method.•The mechanism is discussed in detail based on temperature-dependant experiments.•The electrolyzed water system of A3C2 exhibits a perfect catalytic activity.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2019.06.029