Sequential crystallization of sea urchin-like bimetallic (Ni, Co) carbonate hydroxide and its morphology conserved conversion to porous NiCo2O4 spinel for pseudocapacitors
Sequential crystallization of sea urchin-like bimetallic (Ni, Co) carbonate hydroxide and its morphology conserved conversion to porous NiCo2O4 spinel for pseudocapacitors
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DOI：
10.1039/c1ra00342a
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发表时间：
2011-01-01
期刊：
影响因子：
3.9
通讯作者：
Yang, Shihe
中科院分区：
文献类型：
--
作者：
Xiao, Junwu;Yang, Shihe
我们报告的动力学控制和机制的研究形成海胆状，nickel（Ni，Co）碳酸氢氧化物通过顺序结晶过程，这是很容易转化为多孔NiCo 2 O 4尖晶石与保守的形态，一个很好的候选材料赝电容器。发现双金属碳酸氢氧化物的形成始于单金属碳酸镍氢氧化物的成核，演变成花状微球。随后通过局部溶解-重结晶，从花状微球中的纳米片和在其上成核和生长碳酸氢盐纳米棒，最终导致海胆结构。煅烧后，形成形态保守的NiCo 2 O 4尖晶石纳米结构，其独特地包括具有高比表面积的分级互连孔，适合于快速电子和电解质传输。这与镍钴尖晶石的丰富的氧化还原反应以及它们比单独的镍氧化物和钴氧化物高至少两个数量级的电导率相结合，使得新型纳米结构成为赝电容器的理想候选者。实际上，具有高达198.9 m2/g（-1）的比表面积的多孔NiCo 2 O 4纳米结构表现出比具有类似多孔纳米结构的单钴氧化物（在1 A g（-1）下为60 F/g）和镍氧化物（在1 A g（-）下为194 F g（-1））更高的比电容（在1 A g（-1）下为658 F g（-1））。值得注意的是，即使在10 A g（-1）的高电流密度下，由NiCo 2 O 4多孔材料制成的赝电容器仍保持530 F g（-1）的高比电容，具有优异的循环稳定性。总之，本文报道的简单、可扩展的合成和优异的超级电容器性能预示着这些新型材料在储能方面的大规模应用。
We report kinetic control over and mechanistic studies on the formation of sea urchin-like, bimetallic (Ni, Co) carbonate hydroxide via a sequential crystallization process, which was facilely converted to porous NiCo2O4 spinel with a conserved morphology, an excellent candidate material for pseudocapacitors. The formation of bimetallic carbonate hydroxide was found to start with the nucleation of monometallic nickel carbonate hydroxide evolving into flower-like microspheres. This was followed by the nucleation and growth of the bimetallic carbonate hydroxide nanorods from and on the nanoplates in the flower-like microspheres by localized dissolution-recrystallization, leading finally to the sea urchin structure. After calcination, a morphology conserved NiCo2O4 spinel nanostructure was formed, which uniquely comprises hierarchical, interconnected pores with high specific surface areas suitable for fast electron and electrolyte transport. This, in tandem with the rich redox reactions of nickel cobaltite spinel and their at least two orders of magnitude higher electric conductivity than those of nickel oxides and cobalt oxides alone, renders the novel nanostructures ideal candidates for pseudocapacitors. Indeed, the porous NiCo2O4 nanostructure with a specific surface area of up to 198.9 m(2) g(-1) has exhibited higher specific capacitances (658 F g(-1) at 1 A g(-1)) than the monometallic cobalt oxides (60 F/g at 1 A g(-1)) and nickel oxides (194 F g(-1) at 1 A g(-)) with similar porous nanostructures. Significantly, even at a high current density of 10 A g(-1), the pseudocapacitor made of NiCo2O4 porous materials retained high specific capacitances of 530 F g(-1) with excellent cycling stability. In all, the simple, scalable syntheses and the excellent supercapacitor performance reported here portend large scale applications of these novel materials in energy storage.