Facile synthesis of nickel cobalt sulfide nano flowers for high performance supercapacitor applications

A facile synthesis of nickel cobalt sulfide (NCS) nanoflowers have been deposited successfully onto binder free 3D nickel foam electrodes using simple successive ionic layer adsorption and reaction (SILAR) method for supercapacitor applications. The obtained NCS nanoflowers manifest ultrahigh specific capacitance of 1899 F g^?1 at a scan rate of 5 mV s^?1. The NCS nanoflowers exhibit a prominent energy density of 55.16 Wh kg^?1 at power density of 495 W kg^?1 and superior cyclic stability of 94% after 10000 cycles. In addition, the asymmetric supercapacitor (ASC) device is fabricated using NCS nanoflower as positive and reduced graphene oxide (rGO) as negative electrodes, respectively. The ASC (NCS//rGO) delivered good capacity with excellent energy and power densities within 1.6 V wider potential window. Hence, NCS nanoflowers are an outstanding material for energy storage applications in near future.     

Nickel/cobalt based materials for supercapacitors

We briefly summarize the fundamental mechanism of supercapacitors and classify them into three kinds according to the different energy storage mechanism. We further discuss the energy storage mechanism of nickel/cobalt based materials, and we suggest that these kinds of battery-type materials should be classified into hybrid supercapacitor instead of pseudocapacitors.     

Synthesis of nickel selenide thin films for high performance all-solid-state asymmetric supercapacitors

As a significant semiconductor, nickel selenide shows enormous potential and extensive application prospects in the field of sensor, photocatalysis and supercapacitor. In this paper, nickel selenide (Ni₃Se₂, NiSe) thin films were successfully fabricated on stainless-steel sheet using a facile, effective electrodeposition technique. The morphologies, microstructures and chemical compositions of the thin films are characterized systematically. Electrochemical tests exhibit that the Ni₃Se₂ and NiSe possess high specific capacitance of 581.1 F/g and 1644.7 F/g, respectively. A flexible, all-solid-state asymmetric supercapacitor is assembled by utilizing NiSe film as positive electrode and activated carbon as negative electrode. The solid device delivers a high areal capacitance of 27.0 mF/cm² at the current density of 0.7 mA/cm². The maximum volumetric energy density and power density of the NiSe//AC asymmetric SCs can achieve 0.26 mWh/cm³ and 33.35 mW/cm³, respectively. The device shows robust cycling stability with 84.6% capacitance retention after 10,000 cycles, outstanding flexibility and satisfactory mechanical stability. Moreover, two devices in series can light up a red light-emitting diode, which displayed great potential applications for energy storage.     

双金属离子调控型镍钴氧化物纳米片用于非对称超级电容器

通过水热-煅烧两步法制备了系列镍钴氧化物（NCO）纳米片。通过改变前驱体溶液中的镍、钴离子物质的量之比,进而调控NCO纳米片中的过渡金属离子比例。NCO纳米片的晶相、形貌和结构利用X射线衍射、扫描电子显微镜和X射线光电子能谱表征。此外,对NCO纳米片的电化学性能进行测试。结果表明,NCO-2（Ni_1.95Co₁O_x）纳米片在0.5 A·g^-1电流密度下,比电容为1 096.88 F·g^-1,且经过5 000次循环后具有78.26%的循环稳定性。以NCO-2为正极、活性碳为负极构成的非对称超级电容器,在功率密度为576 W·kg^-1时,能量密度为57.70 Wh·kg^-1。     

双金属离子调控型镍钴氧化物纳米片用于非对称超级电容器

通过水热-煅烧两步法制备了系列镍钴氧化物(NCO)纳米片。通过改变前驱体溶液中的镍、钴离子物质的量之比,进而调控NCO纳米片中的过渡金属离子比例。NCO纳米片的晶相、形貌和结构利用X射线衍射、扫描电子显微镜和X射线光电子能谱表征。此外,对NCO纳米片的电化学性能进行测试。结果表明,NCO-2(Ni_1.95Co₁O_x)纳米片在0.5 A·g^-1电流密度下,比电容为1 096.88 F·g^-1,且经过5 000次循环后具有78.26%的循环稳定性。以NCO-2为正极、活性碳为负极构成的非对称超级电容器,在功率密度为576 W·kg^-1时,能量密度为57.70 Wh·kg^-1。     

Recent advances in metal oxide/hydroxide on three-dimensional nickel foam substrate for high performance pseudocapacitive electrodes

The high demand for long-lasting and portable energy storage devices with enhanced energy and power densities has attracted researcher's interest globally. The three-dimensional (3D) nickel foam is a promising electrode material for storing energy in various devices because they possess large surface area, are very conductive and enjoy a continuous permeable 3D system. This article provides a review and detailed information on the uses of 3D nickel foam-based electrodes with metal oxides/hydroxides of different morphologies for high-performance pseudocapacitors. We assess the limitations and future prospects of 3D nickel foam-based electrodes with metal oxides/hydroxides for industrial application towards enhancing pseudocapacitors' energy storage capability.     

Asymmetric supercapacitors based on high capacitance Ni6MnO8 and graphene

A fast, facile and cost-effective method is used to synthesize Ni₆MnO₈ electrode with high electrochemical performance. The supercapacitor based on Ni₆MnO₈ electrode exhibits excellent stability, high area specific capacitance and promising energy and power density.     

Nitrogen-doped porous carbon coated on MnCo2O4 nanospheres as electrode materials for high-performance asymmetric supercapacitors

Spinel-based nanostructured materials are commonly used as promising electrode materials for supercapacitor applications. The combination of heteroatom-doped carbon material with spinel oxides substantially improves the specific capacitance and cyclic stability. In this work, dopamine-derived nitrogen-doped carbon was coated on spinel phase MnCo₂O₄ nanospheres using simple solvothermal and calcination methods. Surface morphology and the crystalline structure of the prepared MnCo₂O₄@Nitrogen-doped carbon were confirmed by FESEM and X-ray diffraction. The electrochemical performance of MnCo₂O₄@Nitrogen-doped carbon electrode material was analyzed by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. MnCo₂O₄@nitrogen-doped carbon exhibits the highest specific capacitance of 1200 F/g compared to MnCo₂O₄ spheres are 726 F/g at 1 A/g and exhibits excellent cyclic stability (capacitance retention of 87% at 7 A/g after 3000 cycles). The enhanced performance of the composite might be benefitted from the synergistic effect between nitrogen-doped carbon on porous MnCo₂O₄ spheres. Furthermore, an asymmetric supercapacitor device was fabricated by using the optimized composition of MnCo₂O₄@NC-2 as a positive electrode and nitrogen, sulfur-doped reduced graphene oxide (NS-rGO) as a negative electrode, respectively. This asymmetric supercapacitor device achieves a maximum energy density of 61.0 Wh/kg at a power density of 2889 W/kg and possesses excellent capacitance retention of 95% after 5000 cycles at 7 A/g.     

Coupling on-line preconcentration by ion-exchange with microwave plasma torch-atomic emission spectrometry for the determination of cobalt and nickel

In the present work, a simple and sensitive preconcentration-microwave plasma torch-atomic emission spectrometric procedure was carried out for the determination of cobalt and nickel. The method was based upon a flow-injection system with on-line preconcentration of the metal ions on a minicolumn of a strong acid cation-exchange resin. The operation parameters including sample acidity, flow rate, loading time, and eluent concentration, flow rate were studied and optimized. Under the optimal experimental conditions the enrichment factors were calculated as 13.58 and 17.65 for cobalt and nickel, respectively. The relative standard deviations, 3.73% for cobalt and 4.23% for nickel (n = 7), and a sample throughput of 40 h^− 1 were obtained. Furthermore, the limits of detection were shown to be 1.28 and 1.80 μg·L^− 1 for cobalt and nickel, respectively. The method was applied to the determination of cobalt and nickel in tea samples and the accuracy was assessed through recovery experiments.     

Additive-free porous assemblies of Ti_3C_2T_x by freeze-drying for high performance supercapacitors

Ti_3C_2T_x has shown great potential in energy storage filed,but the restacking between Ti_3C_2T_x nanosheets seriously hampers the maximization of its capacitance.In this study,we rationally designed and synthesized porous Ti_3C_2T_x assemblies without any additive by introducing ice as spacers using a facile freeze-drying method.The porous Ti_3C_2T_x assemblies have a three-dimensional network structure,which consists of ultra large Ti_3C_2T_x lamellar walls and lots of macro-and mesopores.It has been proven that there are more-O groups on the surface of the porous Ti_3C_2T_x assemblies than the Ti_3C_2T_x film.The porous Ti_3C_2T_x assemblies deliver a maximum areal capacitance of 1668 mF/cm2 when the mass loading is 8.4 mg/cm2,an optimized specific capacitance of 247.2 F/g when the mass loading is 5.3 mg/cm2,and87% capacitance retention over 10000 cycles.The symmetric solid-state supercapacitors based on the porous Ti_3C_2T_x assemblies show an areal capacitance of 355.8 mF/cm2,the maximum power density of50 mW/cm2 and an outstanding flexibility under different deformation.     

Slurry sampling for the rapid determination of cobalt, nickel and copper in soils and sediments by electrothermal atomic absorption spectrometry

Electrothermal atomic absorption procedures for the rapid determination of cobalt, nickel and copper in soil and sediment samples are presented. The samples are suspended in a hydrofluoric acid solution before being injected into the electrothermal atomizer. Prior mild heating in a microwave oven is recommended for nickel and copper determination. No modifier other than hydrofluoric acid is required. The conventional ashing step is unnecessary since the fast-heating programmes lead to well defined atomization profiles with low background levels that can be corrected using a common deuterium device. Calibration is performed directly using aqueous standards. The results obtained for six certified reference materials confirm the reliability of the procedures.     

Boron and nitrogen dual-doped carbon as a novel cathode for high performance hybrid ion capacitors

A high performance hybrid ion capacitors has been developed by using B, N dual-doped 3D superstructure carbon cathode and prelithiated graphite anode.     

Effect of ion-pairing modifiers in the separation of cobalt,copper, iron,and palladium by pre-column derivatization and high performance liquid chromatography

Summary Multivariate experiment analyses have been used to determine the behaviour, in high-performance liquid chromatography, of cobalt, copper, iron and palladium complexes with 1-nitroso-2-naphthol-6-sodium sulphonate or 2-nitroso-1-naphthol-6-sodium sulphonate ion-associated before injection or during elution with quaternary ammonium salts, namely TDTMABr, CTMABr, and TDDMBACl.The role of the ion-pairing modifiers was to regulate the capacity factors of the complexed metals. The work-up procedures showed that the elution and separation of the metal complex anions were influenced by the concentration and choice of cationic counter compounds. TDTMABr, CTMABr and TDDMBACl were replaced with inorganic salts, such as sodium sulphate, but there was no evidence of better metal separation than with the organic compounds.The studies showed that complexed metal ions can be separated using endcapped silica or polymer as column packing materials. The result of most-potential value was that gradient elution could be used to minimize retention without dissocation of the ion-associates on the column.     

A new (S)-prolinamide modified by an ionic liquid moiety—a high performance recoverable catalyst for asymmetric aldol reactions in aqueous media

New prolinamide derivatives modified with ionic liquid moieties were synthesized and studied as organocatalysts in asymmetric aldol reactions in water. Aldol reactions between cycloalkanones or methylketones and aromatic aldehydes proceeded under studied conditions with high conversions (yields), diastereo- and enantioselectivities in the presence of a hydrophobic catalyst bearing a PF₆ anion (1-5 mol %). The procedure is scalable and the catalyst retained its diastereo- and enantioselectivity over at least four reaction cycles and its activity over at least three reaction cycles.     

A novel collagenase-assisted extraction of active pharmaceutical ingredients from gelatin products for quantitative analysis by high performance liquid chromatography

High performance liquid chromatography (HPLC) is frequently used for quantifying drugs in gelatin capsules. Gelatin has a strong UV absorption that often overlaps with drug absorbances. Therefore, the gelatin capsules must be removed manually before analysis. This study describes a novel extraction method named collagenase-assisted extraction (CAE), which uses collagenase to degrade gelatin into fragments with reduced hydrophobicity, allowing gelatin-related peaks to elute immediately, eliminating interference with the drug peak and enabling use of whole gelatin capsules during drug quantification. Use of CAE eliminates powder loss when opening a gelatin capsule, allows extraction of drugs from the capsule, reduces analytical time, and extends HPLC column life.