General template-free strategy for fabricating mesoporous two-dimensional mixed oxide nanosheets via self-deconstruction/reconstruction of monodispersed metal glycerate nanospheres
General template-free strategy for fabricating mesoporous two-dimensional mixed oxide nanosheets via self-deconstruction/reconstruction of monodispersed metal glycerate nanospheres
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DOI：
10.1039/c8ta00008e
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发表时间：
2018-04-14
影响因子：
11.9
通讯作者：
Yamauchi, Yusuke
中科院分区：
文献类型：
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作者：
Kaneti, Yusuf Valentino;Salunkhe, Rahul R.;Yamauchi, Yusuke
在这项工作中，我们提出了一个通用的无模板策略来制备二维介孔混合氧化物纳米片，如金属钴酸盐（MCo 2 O 4，M = Ni，Zn）通过将高度均匀的钴基金属甘油酸盐纳米球自解构/重构成2D钴基金属甘油酸盐/氢氧化物纳米片，在室温下通过所谓的“水处理”过程诱导，然后在260摄氏度下在空气中煅烧。所提出的“自解构/重建”策略非常有利，因为所得的2D金属钴酸盐纳米片具有非常高的表面积（150-200 m（2）g（-1））和具有窄孔径分布的介孔特征。此外，我们提出的方法还能够使从前体相获得纯金属钴酸盐相的结晶温度降低50 ℃。使用2D介孔NiCo 2 O 4纳米片作为代表性样品，我们发现，它们表现出比电容高6-20倍，并且与通过直接煅烧Ni-Co甘油酸酯纳米球实现的NiCo 2 O 4纳米球相比，电容保持率大大增强。这突出了所提出的用于增强用于超级电容器应用的混合氧化物产品的电化学性能的策略的另一个优点。此外，使用2D NiCo 2 O 4纳米片//氧化石墨烯（GO）组装的非对称超级电容器（ASC）表现出38.53 W·h·kg（-1）的最大能量密度，同时还显示出在5A·g（-1）下2000次循环后91%的高电容保持率。预计所提出的一般方法可以扩展到其他过渡金属元素，用于产生具有增强的表面积和改善的电化学性能的2D混合氧化物纳米片。
In this work, we propose a general template-free strategy for fabricating two-dimensional mesoporous mixed oxide nanosheets, such as metal cobaltites (MCo2O4, M = Ni, Zn) through the selfdeconstruction/reconstruction of highly uniform Co-based metal glycerate nanospheres into 2D Cobased metal glycerate/hydroxide nanosheets, induced by the so-called "water treatment" process at room temperature followed by their calcination in air at 260 degrees C. The proposed 'self-deconstruction/reconstruction' strategy is highly advantageous as the resulting 2D metal cobaltite nanosheets possess very high surface areas (150-200 m(2) g(-1)) and mesoporous features with narrow pore size distribution. In addition, our proposed method also enables the crystallization temperature to achieve pure metal cobaltite phase from the precursor phase to be lowered by 50 degrees C. Using the 2D mesoporous NiCo2O4 nanosheets as a representative sample, we found that they exhibit 6-20 times higher specific capacitance and greatly enhanced capacitance retention compared to the NiCo2O4 nanospheres achieved through the direct calcination of the Ni-Co glycerate nanospheres. This highlights another advantage of the proposed strategy for enhancing the electrochemical performance of the mixed oxide products for supercapacitor applications. Furthermore, the asymmetric supercapacitor (ASC) assembled using the 2D NiCo2O4 nanosheets//graphene oxide (GO) exhibits a maximum energy density of 38.53 W h kg(-1), while also showing a high capacitance retention of 91% after 2000 cycles at 5 A g(-1). It is expected that the proposed general method may be extended to other transition metal elements for creating 2D mixed oxide nanosheets with enhanced surface areas and improved electrochemical performance.