An Approach to Understanding the Electrocatalytic Activity Enhancement by Superexchange Interaction toward OER in Alkaline Media of Ni鈥揊e LDH

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• 作者：Miguel A. Oliver-Tolentino ; Juvencio V谩zquez-Samperio ; Arturo Manzo-Robledo ; Rosa de Guadalupe Gonz谩lez-Huerta ; Jorge L. Flores-Moreno ; Daniel Ram铆rez-Rosales ; Ariel Guzm谩n-Vargas
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 2, 2014
• 年：2014
• 卷：118
• 期：39
• 页码：22432-22438
• 全文大小：358K
• ISSN：1932-7455

文摘

In the present work, the hydrotalcite-like materials known as layered double hydroxides (LDHs) were synthesized. The Ni鈥揂l and Ni鈥揊e materials with different Ni/Fe ratio were obtained by coprecipitation method at variable pH. The LDH structure was verified by X-ray diffraction, Fourier transform infrared, and Raman spectroscopy. No secondary extra phases were observed for any material. The electronic properties were evaluated by UV鈥搗is spectroscopy, while the magnetic ones were followed by electron paramagnetic resonance (EPR). The results suggested that sample H/Ni鈥揊e2 (Ni/Fe = 2) has a ferrimagnetic behavior as a result of the combined action of Ni^II鈥揙H鈥揘i^II, Fe^III鈥揙H鈥揘i^II, and Fe^III鈥揙H鈥揊e^III pairs across the layers and ferromagnetic interactions operating between layers. Furthermore, the material H/Ni鈥揊e1 (Ni/Fe = 1.5) showed a combination of paramagnetic and ferromagnetic interactions which favors a superexchange interaction among metal centers through the OH bridges across the cationic sheets; the superexchange interaction enhances the electrocatalytic activity on the oxygen evolution reaction (OER) in alkaline media. On the other hand, XPS experiments showed that the H/Ni鈥揊e1 did not exhibit structural changes after electrochemical processes. The activity toward the OER was in the order H/Ni鈥揊e1 > H/Ni鈥揊e2 > H/Ni鈥揂l, as was confirmed using in situ linear sweep voltammetry (LSV) coupled with mass spectrometry (differential electrochemical mass spectrometry).