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Coral-Shaped Bifunctional NiCo2O4 Nanostructure: A Material for Highly Efficient Electrochemical Charge Storage and Electrocatalytic Oxygen Evolution Reaction
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2020-06-30 00:00:00 , DOI: 10.1021/acsaem.0c00909
Lakshya Kumar 1 , Meenakshi Chauhan 1 , Purna K. Boruah 2 , Manash R. Das 2, 3 , S. A. Hashmi 4 , Sasanka Deka 1
Affiliation  

Multifunctional materials are quite fascinating and conveniently serve the purpose where two or more efficient materials are required. Herein, we report such a bifunctional material which is new by its morphology and enables the provision of a reliable power output as a supercapacitor electrode as well as oxygen evolution in water splitting as an efficient electrocatalyst material. A coral-shaped NiCo2O4 nanostructure was developed by the oriented attachment pathway of nanocrystal building blocks, which can provide efficient energy storage and energy conversion bifunctional properties which are not realized earlier. Here, the less stable and highly reactive (111) planes of NiCo2O4 small single crystals grow at the expense of the (100) planes in the ⟨111⟩ direction to decrease the total interfacial free energy and get attached with each other to form the coral-shaped nanostructure. The outstanding battery-like capacitive features (e.g., maximum specific capacitance of 1297 F·g–1 or specific capacity of 180 mA·h·g–1, energy density of 45 W·h·kg–1 at high charge–discharge rates, and a minimum stability of 10,000 cycles) with a high Coulombic efficiency (>96%) are attributed to faster ion intercalation between an electrode and an electrolyte and redox pseudocapacitance, high conductivity, and highly porous coral morphology that decreases diffusion distances and exposure of mixed metal valence at the surface. In addition to these features, a higher Ni2+ content enhances the adsorption of OH species on the material surface and a high electrochemically active surface area of the material attributed to a lower overpotential (0.29 V) and longer stability at a higher current density during precious metal-free electrocatalytic oxygen evolution reaction.

中文翻译:

珊瑚状双功能NiCo 2 O 4纳米结构:一种高效的电化学电荷存储和电催化氧放出反应的材料。

多功能材料非常引人入胜,可方便地用于需要两种或更多种高效材料的目的。本文中,我们报道了这样一种双功能材料,其通过其形态是新的,并且能够提供作为超级电容器电极的可靠的功率输出以及作为有效的电催化剂材料的水分解中的氧释放。通过纳米晶体构件的定向附着途径开发了珊瑚状的NiCo 2 O 4纳米结构,该结构可提供有效的能量存储和能量转换双功能特性,这是以前没有实现的。在此,NiCo 2 O 4的不稳定和高反应性(111)平面小的单晶以(111)方向的(100)平面为代价生长,以减少总界面自由能,并彼此附着形成珊瑚状纳米结构。出色的类似电池的电容特性(例如,最大比电容为1297 F·g –1或比容量为180 mA·h·g –1,能量密度为45 W·h·kg –1高充放电效率(> 96%)时具有高的充放电速率和至少10,000次循环的最小稳定性,这归因于电极和电解质之间的离子插入速度更快,以及氧化还原假电容,高电导率和高度多孔的珊瑚形态减少扩散距离并降低表面上混合金属价的暴露。除了这些特征,较高的Ni 2+含量提高OH的吸附-种材料表面上,并具有高归因于较低的超电势(0.29 V)的材料的电化学活性表面积和更长的稳定性在较高的电流密度在无贵金属的电催化氧放出反应中。
更新日期:2020-06-30
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