Cobalt-iron (oxides) water oxidation catalysts: Tracking catalyst redox states and reaction dynamic mechanism

doi:10.1016/j.jcat.2018.06.031

	Cobalt-iron (oxides) water oxidation catalysts: Tracking catalyst redox states and reaction dynamic mechanism
	Zheng, LR; Liang, YQ; Zheng LR(郑黎荣); Zhu, SL; Qi, KZ; Yang, XJ; Cui, ZD; Meng, JF; Li, ZY
刊名	JOURNAL OF CATALYSIS
	2018
卷号	365 页码:227-237
关键词	CoFe(O) catalyst Oxygen evolution reaction Dynamic mechanism d-band center
ISSN号	0021-9517
DOI	10.1016/j.jcat.2018.06.031
文献子类	Article
英文摘要	Developing earth-abundant materials to replace the traditional noble metals in water splitting to meet industrial requirements remains a challenge. Cobalt-iron (oxides) have been widely studied as electrocatalysts for the oxygen evolution reaction (OER), yet our understanding of the OER dynamic reactivity related to the oxidation state changes as well the adsorption energies of surface species on the metal surface linked to the water oxidation are not well-documented. In this work, a facile chemical reduction process is developed for preparation of Co-only, Co3Fe7 alloy, and Fe-only catalysts. We use X-ray photoelectron spectroscopy (XPS) and in-situ X-ray absorption spectroscopy (XAS) to evaluate metal valences and the dynamics of the oxidation state changes of the electrocatalysts in 0.1 M KOH solution, which disclose that about 20% of the Co centers get oxidized in Co-only from the oxidation state of +2 to +3/+4, while only 1% reach to +3 valence for the Co3Fe7 catalyst under cyclic voltammetry (CV) operation. The small edge changes of Fe centers in Fe-only result in negligible changing the oxidation state. Density functional theory (DFT) calculation predicts the mechanism of OER performance, which indicates that the OER activity largely relies on the metal oxidation states on the surface of catalysts. Co3O4 on the surface of Co-only catalyst presenting the most positive d-band center and the fewest e(g) electron contributes to the highest OER activity. Fe-only coated by gamma-Fe2O3 shows the lowest OER performance due to the weakest oxygen adsorption energy of gamma-Fe2O3 as well as the poor electrical conductivity of FeOOH evolved after operation. Co3Fe7 exhibiting medium OER activity is aroused by the co-existence of CoO and gamma-Fe2O3, wherein Co2+ is less active than Co3+. Introducing Fe in Co matrix could depress the formation of Co cations with high oxidation state in as-prepared catalysts, which is not favorable for oxygen production. (C) 2018 Elsevier Inc. All rights reserved.
电子版国际标准刊号	1090-2694
WOS关键词	OXYGEN EVOLUTION ELECTROCATALYSTS ; AUGMENTED-WAVE METHOD ; METAL-SURFACES ; ELECTRONIC-STRUCTURE ; CARBON NANOTUBES ; ANODE MATERIALS ; LOW-TEMPERATURE ; XPS SPECTRA ; FE ; TRANSITION
WOS研究方向	Chemistry ; Engineering
语种	英语
WOS记录号	WOS:000442976400025
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/286262]
专题	高能物理研究所_多学科研究中心
通讯作者	Zheng LR(郑黎荣)
作者单位	中国科学院高能物理研究所
推荐引用方式 GB/T 7714	Zheng, LR,Liang, YQ,Zheng LR,et al. Cobalt-iron (oxides) water oxidation catalysts: Tracking catalyst redox states and reaction dynamic mechanism[J]. JOURNAL OF CATALYSIS,2018,365:227-237.
APA	Zheng, LR.,Liang, YQ.,郑黎荣.,Zhu, SL.,Qi, KZ.,...&Li, ZY.(2018).Cobalt-iron (oxides) water oxidation catalysts: Tracking catalyst redox states and reaction dynamic mechanism.JOURNAL OF CATALYSIS,365,227-237.
MLA	Zheng, LR,et al."Cobalt-iron (oxides) water oxidation catalysts: Tracking catalyst redox states and reaction dynamic mechanism".JOURNAL OF CATALYSIS 365(2018):227-237.