采用改进的Hummer法制备氧化石墨(GO),以干燥浸泡法制备三维氧化石墨烯(r GO)-Ag/泡沫镍(NF)复合材料,对其物相、形貌和组成进行分析,研究了其电化学性能.结果表明,复合材料呈疏松多孔结构,Ag颗粒直径为200 nm,电流密度为5 m A/cm^2时...采用改进的Hummer法制备氧化石墨(GO),以干燥浸泡法制备三维氧化石墨烯(r GO)-Ag/泡沫镍(NF)复合材料,对其物相、形貌和组成进行分析,研究了其电化学性能.结果表明,复合材料呈疏松多孔结构,Ag颗粒直径为200 nm,电流密度为5 m A/cm^2时初次比容量为1.59 F/cm^2,循环1000次后为初始容量的70%,循环稳定性良好.展开更多
The oxidation behaviors of Ni-16Cr-xAl （x=4.5%, 9.0%, mass fraction） superalloy foams in air at 1000℃ were investigated. The effects of AI content on the resistance to high temperature oxidation were examined. The ...The oxidation behaviors of Ni-16Cr-xAl （x=4.5%, 9.0%, mass fraction） superalloy foams in air at 1000℃ were investigated. The effects of AI content on the resistance to high temperature oxidation were examined. The oxidation mechanisms of the foams were discussed. The results show that the resistance to the oxidation of the Ni-16Cr-xA1 based alloy at 1 000 ℃ increases with the content of A1 increasing from 4.5% to 9.0%. Complex oxide products are formed on the surface of the superalloy foams after the oxidation. Cr203 and A1203 are the predominant oxides for the scales of the foams with 4.5% A1 and 9% A1, respectively. Excellent high temperature oxidation resistance and superior pore conformation stability for the Ni-16Cr-xA1 based superalloy foam with 9% A1 can be mainly attributed to the formation of relatively continuous and protective A1203 oxides on the surface of the foam.展开更多
Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and intensively investigat...Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and intensively investigated as binder- and conductor-free electrode for supercapacitors. Based on a three- electrode electrochemical characterization technique, the obtained 3DCGNC electrodes demonstrated a high specific capacitance of 1,760 F·g^-1 and a remarkable rate capability whereby more than 62.5% capacitance was retained when the current density was raised from 1 to 100 A·g^-1. More importantly, asymmetric supercapacitors were assembled by using the obtained 3DCGNC as the cathode and Ketjenblack as a conventional activated carbon anode. The fabricated asymmetric supercapacitors exhibited very promising electrochemical performances with an excellent combination of high energy density of 103.0 Wh·kg^-1 at a power density of 3.0 kW·kg^-1, and excellent rate capability-energy densities of about 70.4 and 26.0 Wh·kg^-1 were achieved when the average power densities were increased to 26.2 and 133.4 kW·kg^-1, respectively. Moreover, an extremely stable cycling life with only 2.7% capacitance loss after 20,000 cycles at a current density of 5 A·g^-1 was achieved, which compares very well with the traditional doublelayer supercapacitors.展开更多
An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide （GO）, and the composite of GO and nickel foam （NF） （GO/NF） was fabricated by ultrasonication-vacuum...An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide （GO）, and the composite of GO and nickel foam （NF） （GO/NF） was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam （rGO/NF） was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and gal- vanostatic charge/discharge measurements. The chemically reduced rGO/NF composite （C-rGO/NF） exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in or- der to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electro- chemical properties. The cycling performance of thermally reduced rGO/NF composite （T-rGO/NF） and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments in- dicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of elec- trochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.展开更多
基金Project (51134003) supported by the National Natural Science Foundation of China
文摘The oxidation behaviors of Ni-16Cr-xAl （x=4.5%, 9.0%, mass fraction） superalloy foams in air at 1000℃ were investigated. The effects of AI content on the resistance to high temperature oxidation were examined. The oxidation mechanisms of the foams were discussed. The results show that the resistance to the oxidation of the Ni-16Cr-xA1 based alloy at 1 000 ℃ increases with the content of A1 increasing from 4.5% to 9.0%. Complex oxide products are formed on the surface of the superalloy foams after the oxidation. Cr203 and A1203 are the predominant oxides for the scales of the foams with 4.5% A1 and 9% A1, respectively. Excellent high temperature oxidation resistance and superior pore conformation stability for the Ni-16Cr-xA1 based superalloy foam with 9% A1 can be mainly attributed to the formation of relatively continuous and protective A1203 oxides on the surface of the foam.
基金This work was supported by the National Natural Science Foundation of China （No. 21001117）, the Shenzhen Peacock Plan （No. KQCX20140522150815065）, and the Starting-Up Funds of South University of Science and Technology of China （SUSTC） through the Talent Plan of the Shenzhen Government. H. T. L. acknowledges the support from a Key Project of the Hunan Provincial Science and Technology Plan （No. 2014FJ2007）.
文摘Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and intensively investigated as binder- and conductor-free electrode for supercapacitors. Based on a three- electrode electrochemical characterization technique, the obtained 3DCGNC electrodes demonstrated a high specific capacitance of 1,760 F·g^-1 and a remarkable rate capability whereby more than 62.5% capacitance was retained when the current density was raised from 1 to 100 A·g^-1. More importantly, asymmetric supercapacitors were assembled by using the obtained 3DCGNC as the cathode and Ketjenblack as a conventional activated carbon anode. The fabricated asymmetric supercapacitors exhibited very promising electrochemical performances with an excellent combination of high energy density of 103.0 Wh·kg^-1 at a power density of 3.0 kW·kg^-1, and excellent rate capability-energy densities of about 70.4 and 26.0 Wh·kg^-1 were achieved when the average power densities were increased to 26.2 and 133.4 kW·kg^-1, respectively. Moreover, an extremely stable cycling life with only 2.7% capacitance loss after 20,000 cycles at a current density of 5 A·g^-1 was achieved, which compares very well with the traditional doublelayer supercapacitors.
基金supported by the National Natural Science Foundation of China (51072047, 21271067)
文摘An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide （GO）, and the composite of GO and nickel foam （NF） （GO/NF） was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam （rGO/NF） was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and gal- vanostatic charge/discharge measurements. The chemically reduced rGO/NF composite （C-rGO/NF） exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in or- der to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electro- chemical properties. The cycling performance of thermally reduced rGO/NF composite （T-rGO/NF） and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments in- dicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of elec- trochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.
