Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors.Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance...Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors.Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance,high redox activity,low cost,and eco-friendliness.In this study,novel three-dimensional （3D） interspersed flower-like nickel hydroxide was assembled under mild conditions.When ammonia was used as the precipitant and inhibitor and CTAB was used as an exfoliation agent,the obtained exfoliated ultrathin Ni（OH）2 nanosheets were assembled into 3D interspersed flower-like nickel hydroxide.In this novel 3D structure,the ultrathin Ni（OH）2 nanosheets not only provided a large contact area with the electrolyte,reducing the polarization of the electrochemical reaction and providing more active sites,but also reduced the concentration polarization in the electrode solution interface.Consequently,the utilization efficiency of the active material was improved,yielding a high capacitance.The electrochemical performance was improved via promoting the electrical conductivity by mixing the as-synthesized Ni（OH）2 with carbon tubes （N-4-CNT electrode）,yielding excellent specific capacitances of 2,225.1 F＆#183;g-1 at 0.5 A＆#183;g-1 in a three-electrode system and 722.0 F＆#183;g-1 at 0.2 A＆#183;g-1 in a two-electrode system.The N-4-CNT//active carbon （AC） device exhibited long-term cycling performance （capacitance-retention ratio of 111.4% after 10,000 cycles at 5 A＆#183;g-1） and a high specific capacitance of 180.5 F＆#183;g-1 with a high energy density of 33.5 W＆#183;h＆#183;kg-1 and a power density of 2,251.6 W＆#183;kg-1.展开更多
CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be t...CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.展开更多
A novel route to the fabrication of hierarchical mesoporous Nd_2O_3 nanostructures including nanospheres and nanoporous network was described. Their structure and morphology evolution of the as-synthesized materials w...A novel route to the fabrication of hierarchical mesoporous Nd_2O_3 nanostructures including nanospheres and nanoporous network was described. Their structure and morphology evolution of the as-synthesized materials were determined by various techniques such as scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transforminfrared spectra, nitrogen adsorption/desorption isotherm, and a formation mechanism was proposed. The results revealed that the Nd_2O_3 nanospheres had the diameter of 300 nm, which were composed of small primary nanoparticles（NPs） with the size of 10 nm. The nanoporous structure also formed the NPs of ca. 10 nm which were connected with each other to form a three-dimensional（3D） texture. This simple and mild approach to fabricate hierarchical mesoporous Nd_2O_3 nanostructures could be easily scaled up and potentially extended to synthesize other oxide hierarchical structures.展开更多
The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peony- like CuO micro/nanostructures about 3 -5μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as ...The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peony- like CuO micro/nanostructures about 3 -5μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as the building block, were self-assembled into multilayer structures under the action of ethidene diamine, and then grew into uniform peony-like CuO architecture. The novel peony-like CuO micro/nanostructures exhibit a high cycling stability and improved rate capability. The peony-like CuO microJnanostructures electrodes show a high reversible capacity of 456 mAhJg after 200 cycles, much higher than that of the commercial CuO nanocrystals at a current 0.1 C. The excellent electrochemical performance of peony-like CuO micro/nanostructures might be ascribed to the unique assembly structure, which not only provide large electrode/electrolyte contact area to accelerate the lithiation reaction, but also the interval between the multilayer structures of CuO nanoplates electrode could provide enough interior space to accommodate the volume change during Li insertion and de-insertion process,展开更多
基金This work was supported by the National Natural Science Foundation of China （Nos. 21671205 and U1407103）, Collaborative Innovation Centre of Henan Textile and Clothing Industry, Innovation Scientists and Technicians Troop Construction Projects of Henan Province （Nos. 164100510007 and CXTD2015018） and Zhengzhou University （Nos. 1421316035 and 2016xjxm258）
文摘Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors.Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance,high redox activity,low cost,and eco-friendliness.In this study,novel three-dimensional （3D） interspersed flower-like nickel hydroxide was assembled under mild conditions.When ammonia was used as the precipitant and inhibitor and CTAB was used as an exfoliation agent,the obtained exfoliated ultrathin Ni（OH）2 nanosheets were assembled into 3D interspersed flower-like nickel hydroxide.In this novel 3D structure,the ultrathin Ni（OH）2 nanosheets not only provided a large contact area with the electrolyte,reducing the polarization of the electrochemical reaction and providing more active sites,but also reduced the concentration polarization in the electrode solution interface.Consequently,the utilization efficiency of the active material was improved,yielding a high capacitance.The electrochemical performance was improved via promoting the electrical conductivity by mixing the as-synthesized Ni（OH）2 with carbon tubes （N-4-CNT electrode）,yielding excellent specific capacitances of 2,225.1 F＆#183;g-1 at 0.5 A＆#183;g-1 in a three-electrode system and 722.0 F＆#183;g-1 at 0.2 A＆#183;g-1 in a two-electrode system.The N-4-CNT//active carbon （AC） device exhibited long-term cycling performance （capacitance-retention ratio of 111.4% after 10,000 cycles at 5 A＆#183;g-1） and a high specific capacitance of 180.5 F＆#183;g-1 with a high energy density of 33.5 W＆#183;h＆#183;kg-1 and a power density of 2,251.6 W＆#183;kg-1.
基金Supported by the National Natural Science Foundation of China (Grant Nos 50772025 and 50872159)the Ministry of Science and Technology of China (Grant No 2008DFR20420)+3 种基金the China Postdoctoral Science Foundation (Grant Nos 20060400042 and 200801044)the Natural Science Foundation of Heilongjiang Province, China (Grant No F200828)the Specialized Research Fund for the Doc-toral Program of Higher Education of China (Grant No 20070217002)the Innovation Foundation of Harbin City (Grant No RC2006QN017016)
文摘CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.
基金Project supported by the Vietnam National Foundation for Science and Technology Development(NAFOSTED)(103.02-2016.41)
文摘A novel route to the fabrication of hierarchical mesoporous Nd_2O_3 nanostructures including nanospheres and nanoporous network was described. Their structure and morphology evolution of the as-synthesized materials were determined by various techniques such as scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transforminfrared spectra, nitrogen adsorption/desorption isotherm, and a formation mechanism was proposed. The results revealed that the Nd_2O_3 nanospheres had the diameter of 300 nm, which were composed of small primary nanoparticles（NPs） with the size of 10 nm. The nanoporous structure also formed the NPs of ca. 10 nm which were connected with each other to form a three-dimensional（3D） texture. This simple and mild approach to fabricate hierarchical mesoporous Nd_2O_3 nanostructures could be easily scaled up and potentially extended to synthesize other oxide hierarchical structures.
基金supported by the National Key Research and Development Program of China(No.2016YFB0601100)the Fundamental Research Funds for the Central Universities(No.FRFBD-16-008A)
文摘The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peony- like CuO micro/nanostructures about 3 -5μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as the building block, were self-assembled into multilayer structures under the action of ethidene diamine, and then grew into uniform peony-like CuO architecture. The novel peony-like CuO micro/nanostructures exhibit a high cycling stability and improved rate capability. The peony-like CuO microJnanostructures electrodes show a high reversible capacity of 456 mAhJg after 200 cycles, much higher than that of the commercial CuO nanocrystals at a current 0.1 C. The excellent electrochemical performance of peony-like CuO micro/nanostructures might be ascribed to the unique assembly structure, which not only provide large electrode/electrolyte contact area to accelerate the lithiation reaction, but also the interval between the multilayer structures of CuO nanoplates electrode could provide enough interior space to accommodate the volume change during Li insertion and de-insertion process,
