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Cobalt/Cobalt Oxide Surface for Water Oxidation
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2019-02-18 00:00:00 , DOI: 10.1021/acssuschemeng.8b06269
Hadi Feizi 1 , Robabeh Bagheri 2 , Zhenlun Song 2 , Jian-Ren Shen 3, 4 , Suleyman I. Allakhverdiev 5, 6, 7, 8, 9 , Mohammad Mahdi Najafpour 1, 10, 11
Affiliation  

Water splitting to produce molecular hydrogen is an essential method to store sustainable energies. One of the bottlenecks for water splitting is the availability of an efficient and stable water-oxidizing catalyst. Herein, metallic cobalt foil, after the treatment under high potential (10–60.0 V), was used for water oxidation. The cobalt/cobalt oxide surface was characterized by various spectroscopic, microscopy, X-ray diffraction, and electrochemical methods. Diffuse reflectance infrared Fourier transform spectroscopy showed peaks for Co oxide at 489 and 595 cm–1 attributed to the stretching of Co–O and bending of O–Co–O bonds in the CoO6 octahedra. Small aggregated particles (ca. 50–100 nm) with a spherical morphology were detected by scanning electron microscopy, and high-resolution transmission electron microscopy from the mechanically separated particles indicated spacings of 2.5–2.6 Å corresponding to the interplanar spacings of the (011) plane for Co3O4. Selected area (electron) diffraction showed concentric rings centered on a bright central spot, indicating a polycrystalline material. Each ring is related to planes of different orientation and different interplanar spacing, attributed to metallic cobalt and cobalt oxides. X-ray diffraction resulted in patterns corresponding to Co3O4 and CoO(OH), and X-ray photoelectron spectroscopy could confirm the formation of metallic cobalt, Co(II) and Co(III) oxides on the surface of the electrode. These results suggest that the oxide on the surface of foil could be a mixture of different phases of Co oxide containing Co3O4 and CoO(OH). Under overpotentials of 460 and 780 mV, current densities of 0.144 and 0.5 A/cm2 were observed at pH-14 without dropping of IR. To the best of our knowledge, the three-dimensional electrode obtained here is among the most efficient cobalt-based water-oxidizing electrodes under alkaline conditions reported so far and may be applied in large scale water-splitting systems.

中文翻译:

用于水氧化的钴/氧化钴表面

分解产生分子氢的水是存储可持续能源的必不可少的方法。分水的瓶颈之一是有效和稳定的水氧化催化剂的可用性。在此,将金属钴箔在高电位(10–60.0 V)下处理后用于水氧化。通过各种光谱,显微镜,X射线衍射和电化学方法对钴/氧化钴表面进行了表征。漫反射红外傅里叶变换光谱显示在489和595 cm –1处Co氧化物的峰,这归因于CoO的拉伸和CoO 6中O–Co–O键的弯曲八面体。通过扫描电子显微镜检测到具有球形形态的小聚集颗粒(约50–100 nm),并且从机械分离的颗粒得到的高分辨率透射电子显微镜显示的间距为2.5–2.6Å,对应于(011 )Co 3 O 4的平面。选定的区域(电子)衍射显示出以明亮的中心点为中心的同心环,表明是多晶材料。每个环与具有不同取向和不同面间距的平面有关,这归因于金属钴和氧化钴。X射线衍射产生对应于Co 3 O 4的图案和CoO(OH),以及X射线光电子能谱可以确认在电极表面上形成了金属钴,Co(II)和Co(III)氧化物。这些结果表明,箔表面上的氧化物可以是包含Co 3 O 4和CoO(OH)的Co氧化物的不同相的混合物。在460和780 mV的过电势下,在pH-14下观察到的电流密度为0.144和0.5 A / cm 2,而IR却没有下降。据我们所知,在迄今报道的碱性条件下,此处获得的三维电极是最有效的钴基水氧化电极之一,可用于大规模的水分解系统。
更新日期:2019-02-18
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