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Redox-Mediated Shape Transformation of Fe3O4 Nanoflakes to Chemically Stable Au−Fe2O3 Composite Nanorods for a High-Performance Asymmetric Solid-State Supercapacitor Device
ACS Sustainable Chemistry & Engineering ( IF 8.4 ) Pub Date : 2018-12-07 00:00:00 , DOI: 10.1021/acssuschemeng.8b04300
Siddheswar Rudra 1 , Arpan Kumar Nayak 2 , Sudipta Koley 3 , Rishika Chakraborty 1 , Pradip K. Maji 4 , Mukul Pradhan 1
Affiliation  

Development of a stable and highly active metal oxide based electrochemical supercapacitor is a major challenge. Herein, we report a Au–Fe2O3 nanocomposite having tiny amount of gold (3 atomic % Au) by employing a simple redox-mediated synthetic methodology using a modified hydrothermal system. Structural and morphological studies of the synthesized Au–Fe2O3 nanocomposite have been performed both experimentally (XRD, IR, Raman, XPS, TEM, and FESEM analyses) and theoretically (WIEN2K). A probable dissolution–nucleation–recrystallization growth mechanism has been suggested to explain the morphological transformation from a Fe3O4 nanoflake to a Au–Fe2O3nanorod. We have observed the superior chemical stability of the Au–Fe2O3 nanocomposite in an acidic medium due to composite formation. The electrochemical measurement of the synthesized Au–Fe2O3 nanocomposite exhibits specific capacitance of ∼570 F g–1 at the current density of 1 A g–1 in 0.5 M H2SO4 electrolyte. The result is superior compared to the mother component, i.e., Fe2O3 (138 F g–1), under identical conditions. It is credited to its higher specific surface area and composite effect. Theoretically, a decrease in band gap associated with increase in conductivity supports the superiority of the Au–Fe2O3 nanocomposite compared to the mother compound, i.e., Fe2O3. In addition, electrochemical kinetic analysis showed that the charge-storage mechanism is mostly from a dominant capacitive process (78% at 1.5 mV s–1). A solid-state asymmetric supercapacitor device has been fabricated using a synthesized Au–Fe2O3 composite nanorod as the positive and activated carbon as the negative electrodes. The asymmetric solid-state device exhibits a maximum energy density of 34.2 Wh kg–1 and power density of 2.73 kW kg–1 at current densities 1 A g–1 and 10 A g–1, respectively. Thus, the synthesized nanocomposite shows excellent activity as a supercapacitor with long-term durability (91% capacitance retention) up to 5000 cycles even in an acidic medium.

中文翻译:

Fe 3 O 4纳米薄片的氧化还原介导的形状转变为化学稳定的Au-Fe 2 O 3复合纳米棒,用于高性能非对称固态超级电容器

稳定和高活性的基于金属氧化物的电化学超级电容器的开发是主要的挑战。在这里,我们通过采用简单的氧化还原介导的合成方法,使用改良的水热系统,报告了一种具有少量金(3原子%Au)的Au-Fe 2 O 3纳米复合材料。已通过实验(XRD,IR,拉曼,XPS,TEM和FESEM分析)和理论上(WIEN2K)进行了合成Au-Fe 2 O 3纳米复合材料的结构和形态研究。已经提出了可能的溶解-成核-再结晶生长机制来解释从Fe 3 O 4纳米片到Au-Fe 2 O的形态转变。3纳米棒。我们已经观察到由于复合物的形成,Au–Fe 2 O 3纳米复合材料在酸性介质中具有出色的化学稳定性。在0.5 MH 2 SO 4电解质中,在1 A g –1的电流密度下,合成的Au–Fe 2 O 3纳米复合材料的电化学测量显示出约570 F g –1的比电容。结果优于母体成分Fe 2 O 3(138 F g –1),条件相同。它被认为具有较高的比表面积和复合效果。从理论上说,与在导电性增加相关的带隙的降低支持的Au-Fe的优越性2 ø 3相比母体化合物,即纳米复合材料,铁2 ö 3。此外,电化学动力学分析表明,电荷存储机理主要来自于主要的电容过程(在1.5 mV s –1时为78%)。使用合成的Au–Fe 2 O 3制备了固态不对称超级电容器复合纳米棒为正极,活性炭为负极。在电流密度分别为1 A g –1和10 A g –1时,这种非对称固态器件的最大能量密度为34.2 Wh kg –1,功率密度为2.73 kW kg –1。因此,即使在酸性介质中,合成的纳米复合材料作为超级电容器也表现出优异的活性,具有高达5000次循环的长期耐久性(91%的电容保持率)。
更新日期:2018-12-07
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