聚吡咯包覆NiCo_2S_4纳米管阵列的制备及其赝电容性能北大核心CSCD

使用两步水热法在泡沫镍表面生长NiCo_2S_4纳米管阵列,再通过电化学聚合技术将聚吡咯包覆在NiCo_2S_4纳米管表面形成核壳式复合材料。通过多种手段表征复合材料的物相与微结构,表明管外径约130nm,管壁厚约15nm,聚吡咯包覆膜平均厚度约8nm。研究聚吡咯包覆对NiCo_2S_4纳米管赝电容性能的影响,揭示聚吡咯改善了NiCo_2S_4纳米管的比电容、充放电性能、倍率性能和循环性能。放电比容量与未包覆的相比从1123F·g^(-1)增长到1524F·g^(-1),增加了36%;3000次循环后,聚吡咯包覆NiCo_2S_4仍释放比容量1096F·g^(-1),相比于第一次的保持率为78.5%,而未包覆的比容量只有22%的保持率。赝电容性能的改善主要是由于聚吡咯提高了NiCo_2S_4纳米管的电导率和结构稳定性。     

NiCo_2O_4微球的制备及其电化学性能

通过简单的水热法以及后续热处理,成功合成介孔NiCo_2O_4微球。利用FESEM、TEM、XPS和电化学工作站对样品的表面形貌、元素价态和电化学性能进行表征。结果表明:合成的NiCo_2O_4拥有丰富的多孔纳米针状结构,表现出较高的比表面积。由于这种三维多孔纳米结构,当NiCo_2O_4微球作为电极材料时,展现出优异的电容特性,在1A·g-1的电流密度下比电容高达1 554F·g-1,而且当电流密度增加到20A·g-1时,电容保持率为87.5%。另外,在5A·g-1的电流密度下,经过2 000次的充放电循环后,比电容仍能保持初始电容的90.4%。良好的电化学性能表明,NiCo_2O_4微球是一种理想的超级电容器电极材料。     

表面活性剂对NiCo2S4纳米薄膜的电化学性能影响的研究

通过水热法在泡沫镍上成功制备了纳米结构的NiCo₂S₄薄膜, 主要包括前驱体制备及硫化过程。研究表明, 制备过程中添加不同种类的表面活性剂会对NiCo₂S₄薄膜的形貌、结构和电化学性能产生影响。添加表面活性剂后, NiCo₂S₄会自组装逐渐形成三维纳米片网状结构。在所有的NiCo₂S₄薄膜中, 添加SDS表面活性剂的薄膜表现出最高的比电容(在0.5 A/g电流密度下达到2893 F/g)、出色的倍率特性(在10 A/g电流密度下达到1890.6 F/g)和良好的循环稳定性(1000次循环后保持率为96.1%)。研究结果表明纳米网状的NiCo₂S₄是一种极具潜力的超级电容器电极材料。     

NiCo2O4/C复合电极材料的制备以及超级电容性能

采用化学共沉淀法合成了纳米级NiCo2O4/C复合材料,并以X射线衍射(XRD)、扫描电镜(SEM)对样品进行了结构和形貌的表征,结果表明,合成的复合材料为立方尖晶石结构,其粒径大小为30～40nm,颗粒呈球形且分布均匀。循环伏安(CV)、恒电流充放电测试表明,NiCo2O4/C复合材料在6mol/LKOH水系电解液中表现出优异的超级电容特征,在0～0.9V的电位范围内,NiCo2O4/C电极材料比电容量可高达290.49F/g,并具有良好的可逆性和优异的循环性能。     

NiCo2S4@ACF异质电极材料的绿色制备及其超级电容性能研究

传统的NiCo₂S₄硫化过程需要高温加热, 耗能较大, 并且单纯的硫化物导电性差。本工作通过绿色环保的室温硫化法成功制备出以活性炭纤维(ACF)为核, NiCo₂S₄为壳的复合异质结电极材料(NiCo₂S₄@ACF)。NiCo₂S₄@ACF复合电极材料的层状结构, 有效增大了与电解液的接触面积, 改善了电子的传输路径, 使其具有更优良的电化学性能。当电流密度为1 A/g时, 其比电容值高达1541.6 F/g (678 μF/cm²)。另外, NiCo₂S₄@ACF和ACF分别作正负极组装成的非对称超级电容器(Asymmetric Supercapacitors, ASC)展现了良好的电化学性能: 能量密度高, 当功率密度为800 W/kg时, 能量密度高达49.38 Wh/kg; 循环性能稳定, 循环充放电2000圈后比电容仍能保持90.27%。研究表明, NiCo₂S₄@ACF复合电极材料是一种应用前景广阔的超级电容器电极材料。     

NiCo2O4/Co3O4纳米材料的球磨法制备及电化学性能

通过高能球磨碳酸镍、碱式碳酸钴的方法制备了NiCo2O4/Co3O4复合材料.系统研究了原料质量比、球磨参数以及退火温度等对材料的微观形貌、结构、组份以及反应活化能和电化学性能的影响.结果表明,在碳酸镍和碱式碳酸钴质量比为2:8,球磨时间为48 h,退火温度为300℃条件下制得复合材料在电位范围0～0.45 V,电流密...     

不同形貌纳米NiCo2O4的研究进展

纳米NiCo₂O₄因其独特的理化性能已广泛应用于能源储存与转换, 尤其是超级电容器领域。鉴于纳米材料的形貌对其性能的重要影响, 本文综述了不同形貌(纳米针、纳米线、纳米管、纳米片、球状、纳米花、珊瑚状及三维复合结构)纳米NiCo₂O₄的合成方法及其在相关领域的应用, 叙述了各种制备方法的基本原理、特点以及对纳米NiCo₂O₄形貌的调控规律。同时, 简要说明了材料形貌与尺寸对其性能影响的机理及规律。最后, 展望了纳米NiCo₂O₄在能源储存与转换领域中未来的发展方向。     

LiMn2O4纳米晶的低温水热法合成及表征

以KMnO4、LiOH、环己酮为原料在120℃,10h用水热法直接合成了LiMn2O4纳米晶.通过XRD,FTIR,TEM测试表明产物为纯相尖晶石LiMn2O4纳米颗粒.电化学性能初步测试表明所得LiMn2O4纳米颗粒具有良好的电化学性能.     

Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合镀层的性质和组成研究

为了获得耐蚀性能优异的复合化学镀层,利用中性化学复合镀技术,在A3碳钢片表面制备了金黄色光亮致密的Cu-Sn-P-ZnCr2S4和Cu-Sn-P-CdCr2S4纳米复合化学镀层.用扫描电子显微镜(SEM)观察了镀层外貌;以称重法测定厚度;通过5%NaCl溶液、1%H2S气体加速腐蚀试验、抗粘性试验及室温氧化试验等多种手段测定了其性能;用X射线光电子谱(XPS)及俄歇电子能谱(AES)测定了其价态及组成.结果表明:Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合材料镀层的性能优于Cu-Sn-P合金镀层,复合镀层Cu-Sn-P-ZnCr2S4中,各原子百分数(%)约为: Cu 68.00,Sn 3.50,P 6.90,Zn 2.10,Cr 4.20, S 8.40,C 6.80;Cu-Sn-P-CdCr2S4中:Cu 69.00,Sn 3.30,P 5.90,Cd 2.4,Cr 4.8, S 9.60,C 4.80.Cu-Sn-P-ZnCr2S4占镀层的93.10%,Cu-Sn-P-CdCr2S4占镀层的95.00%.所得镀层耐蚀性好,耐盐水及室温氧化性能均优于Q235钢片和相近厚度的Cu-Sn-P合金镀层.     

Electrolyte Engineering on Performance Enhancement of NiCo2S4 Anode for Sodium Storage

NiCo₂S₄ is an attractive anode for sodium-ion batteries (SIBs) due to its high capacity and excellent redox reversibility. Practical deployment of NiCo₂S₄ electrode in SIBs, however, is still hindered by the inferior capacity and unsatisfactory cycling performance, which result from the mismatch between the electrolyte chemistry and electrode. Herein, a functional electrolyte containing 1.0 m NaCF₃SO₃ in diethylene glycol dimethyl ether (DEGDME) (1.0 m NaCF₃SO₃-DEGDME) is developed, which can be readily used for NiCo₂S₄ anode with high initial coulomb efficiency (96.2%), enhanced cycling performance, and boosted capacities (341.7 mA h g⁻¹ after 250 continuous cycles at the current density of 200 mA g⁻¹). The electrochemical tests and related phase characterization combined with density functional theory (DFT) calculation indicate the ether-based electrolyte is more suitable for the NiCo₂S₄ anode in SIBs due to the formation of a stable electrode–electrolyte interface. Additionally, the importance of the voltage window is also demonstrated to further optimize the electrochemical performance of the NiCo₂S₄ electrode. The formation of sulfide intermediates during charging and discharging is predicted by combining DFT and verified by in situ XRD and HRTEM. The findings indicate that electrolyte engineering would be an effective way of performance enhancement for sulfides in practical SIBs.     

Surface Spin Enhanced High Stable NiCo2S4 for Energy-Saving Production of H2 from Water/Methanol Coelectrolysis at High Current Density

Nickel based materials are promising electrocatalysts to produce hydrogen from water in alkaline media. However, the stability is of great challenge, limiting its practical material functions. Herein, a new technique for electro-deposition flower-like NiCo₂S₄ nanosheets on carbon-cloth (CC@NiCo₂S₄) is proposed for energy-saving production of H₂ from water/methanol coelectrolysis at high current density by constructing array architectures and regulating surface magnetism. The optimized and fine-tuned magnetism on the surface of the electrochemical in situ grown CC@NiCo₂S₄ nanosheet array result in (0 1 −1) surface universally exposed, high catalytic activity for methanol electrooxidation, and long-term stability at high current density. X-ray photoelectron spectroscopy in combination of density functional theory calculations confirm the valence electron states and spin of d electrons for the surface of NiCo₂S₄, which enhance the surface stability of catalysts. This technology may be utilized to alter the surface magnetism and increase the stability of Ni-based electrocatalytic materials in general.     

Defect‐Enriched Nitrogen Doped–Graphene Quantum Dots Engineered NiCo2S4 Nanoarray as High‐Efficiency Bifunctional Catalyst for Flexible Zn‐Air Battery

Flexible Zn‐air batteries have recently emerged as one of the key energy storage systems of wearable/portable electronic devices, drawing enormous attention due to the high theoretical energy density, flat working voltage, low cost, and excellent safety. However, the majority of the previously reported flexible Zn‐air batteries encounter problems such as sluggish oxygen reaction kinetics, inferior long‐term durability, and poor flexibility induced by the rigid nature of the air cathode, all of which severely hinder their practical applications. Herein, a defect‐enriched nitrogen doped–graphene quantum dots (N‐GQDs) engineered 3D NiCo₂S₄ nanoarray is developed by a facile chemical sulfuration and subsequent electrophoretic deposition process. The as‐fabricated N‐GQDs/NiCo₂S₄ nanoarray grown on carbon cloth as a flexible air cathode exhibits superior electrocatalytic activities toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), outstanding cycle stability (200 h at 20 mA cm^?2), and excellent mechanical flexibility (without observable decay under various bending angles). These impressive enhancements in electrocatalytic performance are mainly attributed to bifunctional active sites within the N‐GQDs/NiCo₂S₄ catalyst and synergistic coupling effects between N‐GQDs and NiCo₂S₄. Density functional theory analysis further reveals that stronger OOH* dissociation adsorption at the interface between N‐GQDs and NiCo₂S₄ lowers the overpotential of both ORR and OER.     

One‐Step Hydrothermal Tailoring of NiCo2S4 Nanostructures on Conducting Oxide Substrates as an Efficient Counter Electrode in Dye‐Sensitized Solar Cells

A one‐step in situ tailoring of NiCo₂S₄ nanostructures is demonstrated on fluorine‐doped tin oxide (FTO) as Pt‐free counter electrodes (CEs) for dye‐sensitized solar cells (DSSCs) with performance surpassing that of a conventional Pt‐sputtered CE. An interconnected NiCo₂S₄ nanosheet network is successfully constructed on the FTO glass via a hydrothermal method, attributed to the synergistic effect of structure‐directing hexamethylenetetramine and L‐cysteine. A growth mechanism is proposed, and the effects of nanostructures and sulfur atomic percentages on the electrocatalytic performance are discussed in depth. A DSSC with the optimized interconnected NiCo₂S₄ nanosheet CE exhibits higher power conversion efficiency (7.22%) compared to that with a conventional Pt‐sputtered CE (6.87%) due to excellent charge transport properties and enhanced electrocatalytic activity of the NiCo₂S₄ nanostructures. This work showcases the strong potential of nanostructured ternary chalcogenides, which are composed of earth‐abundant elements and prepared through a single‐step hydrothermal process without tedious posttreatments, to reduce the dependence of platinum in DSSCs and other electrochemical devices.     

Ionic Liquid‐Controlled Growth of NiCo2S4 3D Hierarchical Hollow Nanoarrow Arrays on Ni Foam for Superior Performance Binder Free Hybrid Supercapacitors

A significant development in the design of a NiCo₂S₄ 3D hierarchical hollow nanoarrow arrays (HNA)‐based supercapacitor binder free electrode assembled by 1D hollow nanoneedles and 2D nanosheets on a Ni foam collector through controlling ionic liquid 1‐octyl‐3‐methylimidazolium chloride ([OMIm]Cl) concentration is reported. The unique NiCo₂S₄‐HNA electrode acquires high specific capacity (1297 C g^?1 at 1 A g^?1, 2.59 C cm^?2 at 2 mA cm^?2), excellent rate capability (maintaining 73.0% at 20 A g^?1), and long operational life (maintaining 92.4% after 10 000 cycles at 5 A g^?1), which are superior to those for 1D hollow nanoneedle arrays (HNN) and 2D porous nanoflake arrays (PNF). The outstanding electrochemical performance is attributed to the novel 3D structure with large specific surface, hollow cores, high porosity as well as stable architecture. In addition, a hybrid supercapacitor applying 3D NiCo₂S₄‐HNA as the positive electrode and active carbon as the negative electrode exhibits a high energy density of 42.5 Wh kg^?1 at a power density of 2684.2 W kg^?1 in an operating voltage of 1.6 V. Robust cycling stability is also expressed with 84.9% retention after repeating 10 000 cycles at 5 A g^?1, implying their great potential in superior‐performance supercapacitors.