Porous Hybrid Composites of Few‐Layer MoS2 Nanosheets Embedded in a Carbon Matrix with an Excellent Supercapacitor Electrode Performance

Porous hierarchical architectures of few‐layer MoS₂ nanosheets dispersed in carbon matrix are prepared by a microwave‐hydrothermal method followed by annealing treatment via using glucose as C source and structure‐directing agent and (NH₄)₂MoS₄ as both Mo and S sources. It is found that the morphology and size of the secondary building units (SBUs), the size and layer number of MoS₂ nanosheets as well as the distribution of MoS₂ nanosheets in carbon matrix, can be effectively controlled by simply adjusting the molar ratio of (NH₄)₂MoS₄ to glucose, leading to the materials with a low charge–transfer resistance, many electrochemical active sites and a robust structure for an outstanding energy storage performance including a high specific capacitance (589 F g⁻¹ at 0.5 A g⁻¹), a good rate capability (364 F g⁻¹ at 20 A g⁻¹), and an excellent cycling stability (retention 104% after 2000 cycles) for application in supercapacitors. The exceptional rate capability endows the electrode with a high energy density of 72.7 Wh kg⁻¹ and a high power density of 12.0 kW kg⁻¹ simultaneously. This work presents a facile and scalable approach for synthesizing novel heterostructures of MoS₂‐based electrode materials with an enhanced rate capability and cyclability for potential application in supercapacitor.     

基于花状MoS2微米材料的葡萄糖生物传感器的制备及其性能研究

本研究采用水热法制备了花状MoS₂微米材料, 将其作为电极构建葡萄糖生物传感器, 并研究了相关性能。结果表明: 水热法制备的MoS₂呈花状, 具有较好的结晶质量, 尺寸约为3.6 μm, 比表面积约为9.646 m²/g; MoS₂电极具有优良的电催化活性, 且电阻抗较小, 使得传感器对葡萄糖具有较好的响应。葡萄糖检测结果表明, 该传感器在0~20 mmol/L范围内, 氧化峰电流与葡萄糖浓度呈良好的线性关系, 相关系数(R)为0.9653, 灵敏度为262 μA•L/mmol。     

超级电容器用活性炭电极材料的研究进展

活性炭因具有制备简单、成本低、比表面积大、导电性好以及化学稳定性高等特点,作为超级电容器电极材料已得到广泛应用.论述了活性炭电极超级电容器的工作原理及活性炭物化性质对超级电容器电化学性能的影响,介绍了活性炭电极材料的最新研究进展,展望了其应用前景,指出寻找新炭源及活化技术、探索活性炭孔结构和表面性质的有效控制手段、开发活性炭复合材料等是该领域今后研究的重点方向.     

Synthesis of Few‐Layer MoS2 Nanosheet‐Coated TiO2 Nanobelt Heterostructures for Enhanced Photocatalytic Activities

MoS₂ nanosheet‐coated TiO₂ nanobelt heterostructures—referred to as TiO₂@MoS₂—with a 3D hierarchical configuration are prepared via a hydrothermal reaction. The TiO₂ nanobelts used as a synthetic template inhibit the growth of MoS₂ crystals along the c‐axis, resulting in a few‐layer MoS₂ nanosheet coating on the TiO₂ nanobelts. The as‐prepared TiO₂@MoS₂ heterostructure shows a high photocatalytic hydrogen production even without the Pt co‐catalyst. Importantly, the TiO₂@MoS₂ heterostructure with 50 wt% of MoS₂ exhibits the highest hydrogen production rate of 1.6 mmol h^?1g^?1. Moreover, such a heterostructure possesses a strong adsorption ability towards organic dyes and shows high performance in photocatalytic degradation of the dye molecules.     

MoS2/有序介孔碳复合材料的制备及性能研究

采用水热法合成了纯MoS2及MoS2/有序介孔碳复合材料(MoS2/OMC)。X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)及循环伏安曲线(CV)等分别用来表征样品的结构、形貌及电化学性能。实验结果表明,以钼酸钠和硫脲分别为钼、硫源合成的MoS2/OMC复合材料的性能较纯MoS2有明显提升。MoS2/OMC复合材料的首次放电容量达到1247mAh/g,第二、三次的放电容量分别为948mAh/g、894mAh/g,容量保持率为94%。二、三次充、放电曲线的近乎重合及高倍率下的高放电容量,亦表明该复合电极有极佳的循环稳定性及良好的可逆性。     

喷雾干燥法制备石榴状嵌套结构MoS2

将硫代钼酸盐溶液用喷雾干燥法获得前驱体,通过分解前驱体制备了嵌套结构MoS2.前驱体在650℃下分解5小时获得的MoS2颗粒,具有石榴状球形结构,且内部嵌套有较小的多面体.本文结合已有报道讨论了它的形成和生长机制.     

准三维MoS2/graphene复合材料储锂性能研究

本研究以氧化石墨烯为前驱体, 利用钼酸钠和硫脲通过水热法在不同阳离子表面活性剂(C₁₄TAB, C₁₆TAB, C₁₈TAB)的辅助下合成得到MoS₂/GF复合结构。XRD和SEM分析表明, MoS₂/GF复合材料因阳离子表面活性剂的不同而呈现不同的结构和表面形貌; 电化学性能测试表明其结构和表面形貌对电极的容量、循环稳定性和倍率性能都有较大影响。相比于C₁₆TAB和C₁₈TAB, C₁₄TAB辅助合成的MoS₂/GF复合结构具有最高的首次放电容量(955 mAh/g), 50次循环后仍保持751 mAh/g的可逆容量, 而且倍率性能更好。本研究揭示MoS₂/GF复合材料电化学性能的提升可归因于其独特的praticle-on-sheet结构以及MoS₂与石墨烯之间的协同作用。     

二硫化钼/石墨烯复合材料的一步水热合成及电催化性能EI北大核心CSCD

为提高催化剂的催化活性及稳定性,采用一步水热法合成二硫化钼/石墨烯(MoS 2/RGO)复合催化剂。利用X射线衍射仪、扫描电子显微镜、透射电子显微镜及旋转圆盘电极等分别对催化剂的物理-化学性能进行表征。结果表明:与石墨烯复合后,MoS 2呈少层花瓣状结构,层间距增加且均匀附着在石墨烯薄层上;二硫化钼催化剂的氧还原过程主要以二电子途径进行,而MoS 2/RGO复合催化剂在氧还原过程中可发挥协同催化作用,其氧还原过程中平均转移电子数为3.58,且复合催化剂在20000 s后的电流密度保持率高达89.7%。     

CaF2-MoS2铁镍基自润滑复合材料的摩擦学性能研究

以不同含量的MoS2、CaF2为润滑相,加入Cu、Fe和合金等元素,采用粉末冶金烧结工艺制备了具有在室温和高温下均有自润滑作用的铁镍基复合材料.采用UMT-2摩擦磨损试验仪、扫描电镜以及X射线衍射测试并分析了复合材料的摩擦磨损性能以及机理.结果表明,随着MoS2含量的减少、CaF2含量的增加,在室温时摩擦系数、磨损率均增大;而高温时摩擦系数、磨损率先降低后增大.当MoS2、CaF2各含3％(质量百分数)时复合材料在室温和高温时拥有最佳的摩擦性能.该复合材料室温时主要是MoS2起润滑作用,降低材料的摩擦磨损;而高温时MoS2、CaF2与金属相互作用生成CrxSx+1以及MoO2、CaMoO4、Fe2O3、FeMo4F6等物质,这些物质在摩擦表面形成复合润滑膜而起润滑作用.     

Synthesis of Co-Doped MoS2 Monolayers with Enhanced Valley Splitting

Internal magnetic moments induced by magnetic dopants in MoS₂ monolayers are shown to serve as a new means to engineer valley Zeeman splitting (VZS). Specifically, successful synthesis of monolayer MoS₂ doped with the magnetic element Co is reported, and the magnitude of the valley splitting is engineered by manipulating the dopant concentration. Valley splittings of 3.9, 5.2, and 6.15 meV at 7 T in Co-doped MoS₂ with Co concentrations of 0.8%, 1.7%, and 2.5%, respectively, are achieved as revealed by polarization-resolved photoluminescence (PL) spectroscopy. Atomic-resolution electron microscopy studies clearly identify the magnetic sites of Co substitution in the MoS₂ lattice, forming two distinct types of configurations, namely isolated single dopants and tridopant clusters. Density functional theory (DFT) and model calculations reveal that the observed enhanced VZS arises from an internal magnetic field induced by the tridopant clusters, which couples to the spin, atomic orbital, and valley magnetic moment of carriers from the conduction and valence bands. The present study demonstrates a new method to control the valley pseudospin via magnetic dopants in layered semiconducting materials, paving the way toward magneto-optical and spintronic devices.     

Interface Modulation of MoS2/Metal Oxide Heterostructures for Efficient Hydrogen Evolution Electrocatalysis

Developing efficient earth‐abundant MoS₂ based hydrogen evolution reaction (HER) electrocatalysts is important but challenging due to the sluggish kinetics in alkaline media. Herein, a strategy to fabricate a high‐performance MoS₂ based HER electrocatalyst by modulating interface electronic structure via metal oxides is developed. All the heterostructure catalysts present significant improvement of HER electrocatalytic activities, demonstrating a positive role of metal oxides decoration in promoting the rate‐limited water dissociation step for the HER mechanism in alkaline media. The as‐obtained MoS₂/Ni₂O₃H catalyst exhibits a low overpotential of 84 mV at 10 mA cm^?2 and small charge‐transfer resistance of 1.5 Ω in 1 m KOH solution. The current density (217 mA cm^?2) at the overpotential of 200 mV is about 2 and 24 times higher than that of commercial Pt/C and bare MoS₂, respectively. Additionally, these MoS₂/metal oxides heterostructure catalysts show outstanding long‐term stability under a harsh chronopotentiometry test. Theoretical calculations reveal the varied sensitivity of 3d‐band in different transition oxides, in which Ni‐3d of Ni₂O₃H is evidently activated to achieve fast electron transfer for HER as the electron‐depletion center. Both electronic properties and energetic reaction trends confirm the high electroactivity of MoS₂/Ni₂O₃H in the adsorption and dissociation of H₂O for highly efficient HER in alkaline media.     

一步合成还原氧化石墨烯/MnO2复合材料及其电化学性能

通过水热法, 利用氧化石墨烯(GO)和二价锰盐, 一步合成了还原氧化石墨烯/MnO₂(RGO/M)复合电极材料。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、拉曼光谱(RS)、傅里叶红外光谱(FTIR)和场发射扫描电镜(FESEM)等测试电极材料的物性, 通过循环伏安、交流阻抗和恒流充放电等方法研究电极材料的电化学性能。结果表明, 在一定水热反应条件下, 通过控制GO与二价锰盐配比, 可以调节RGO/M的结构及其电化学性能。在1 A/g电流密度下, 所得RGO/M复合电极的比电容可达277 F/g, 经过500次循环后, 保持率达到98%。     

CTAB辅助水热合成球状纳米花MoS2/C复合材料及其电化学性能研究

以钼酸钠(Na₂MoO₄·2H₂O)、硫脲(NH₂CSNH₂)、CTAB为原料, 利用水热法合成了MoS₂/C球状纳米花复合材料。通过XRD、SEM、TEM、TG等分析测试方法, 研究了不同CTAB添加量对MoS₂/C复合材料的微观结构、表面形貌的影响规律, 结果显示, 有部分无定形碳嵌入了MoS₂层间, 并抑制了MoS₂(002)面的堆积。电化学测试表明: 与纯MoS₂相比, MoS₂/C复合材料具有更好的电化学性能, 当加入0.025 g CTAB时首次放电比容量达到730 mAh/g, 在100 mA/g的电流密度下经过100次循环比容量稳定在415 mAh/g。在此基础上讨论了MoS₂/C球状纳米花复合材料的可能生长机理以及对材料电化学性能的影响规律。     

Efficient Regulation of Polysulfides by MoS2/MoO3 Heterostructures for High-Performance Li-S Batteries

The notorious shuttle effect and sluggish conversion of polysulfides seriously hinder the practical application of Lithium-sulfur (Li-S) batteries. In this study, a novel architecture of MoS₂/MoO₃ heterostructure uniformly distributed on carbon nanotubes (MoS₂/MoO₃@CNT) is designed and introduced into Li-S batteries via decorating commercial separator to regulate the redox reactions of polysulfides. Systematic experiments and theoretical calculations showed that the heterostructure not only provides sufficient surface affinity to capture polysulfides and acts as an active catalyst to promote the conversion of polysulfides, but also the highly conductive CNT enables rapid electron/ion migration. As a result, Li-S batteries with the MoS₂/MoO₃@CNT-PP separator deliver an impressive reversible capacity (1015 mAh g⁻¹ at 0.2 A g⁻¹ after 100 cycles), excellent rate capacity (873 mAh g⁻¹ at 5 A g⁻¹), and low self-discharge capacity loss (94.6% capacity retention after 7 days of standing). Moreover, even at an elevated temperature of 70 °C, it still exhibits high-capacity retention (800 mAh g⁻¹ at 1 A g⁻¹ after 100 cycles). Encouragingly, when the sulfur load is increased to 8.7 mg cm⁻², the high reversible areal capacity of 6.61 mAh cm⁻² can be stably maintained after 100 cycles, indicating a high potential for practical application.     

Phosphorus‐Mediated MoS2 Nanowires as a High‐Performance Electrode Material for Quasi‐Solid‐State Sodium‐Ion Intercalation Supercapacitors

Molybdenum disulfide (MoS₂) is a promising electrode material for electrochemical energy storage owing to its high theoretical specific capacity and fascinating 2D layered structure. However, its sluggish kinetics for ionic diffusion and charge transfer limits its practical applications. Here, a promising strategy is reported for enhancing the Na⁺‐ion charge storage kinetics of MoS₂ for supercapacitors. In this strategy, electrical conductivity is enhanced and the diffusion barrier of Na⁺ ion is lowered by a facile phosphorus‐doping treatment. Density functional theory results reveal that the lowest energy barrier of dilute Na‐vacancy diffusion on P‐doped MoS₂ (0.11 eV) is considerably lower than that on pure MoS₂ (0.19 eV), thereby signifying a prominent rate performance at high Na intercalation stages upon P‐doping. Moreover, the Na‐vacancy diffusion coefficient of the P‐doped MoS₂ at room temperatures can be enhanced substantially by approximately two orders of magnitude (10^?6–10^?4 cm² s^?1) compared with pure MoS₂. Finally, the quasi‐solid‐state asymmetrical supercapacitor assembled with P‐doped MoS₂ and MnO₂, as the positive and negative electrode materials, respectively, exhibits an ultrahigh energy density of 67.4 W h kg^?1 at 850 W kg^?1 and excellent cycling stability with 93.4% capacitance retention after 5000 cycles at 8 A g^?1.     

Cobalt Covalent Doping in MoS2 to Induce Bifunctionality of Overall Water Splitting

The layer‐structured MoS₂ is a typical hydrogen evolution reaction (HER) electrocatalyst but it possesses poor activity for the oxygen evolution reaction (OER). In this work, a cobalt covalent doping approach capable of inducing HER and OER bifunctionality into MoS₂ for efficient overall water splitting is reported. The results demonstrate that covalently doping cobalt into MoS₂ can lead to dramatically enhanced HER activity while simultaneously inducing remarkable OER activity. The catalyst with optimal cobalt doping density can readily achieve HER and OER onset potentials of ?0.02 and 1.45 V (vs reversible hydrogen electrode (RHE)) in 1.0 m KOH. Importantly, it can deliver high current densities of 10, 100, and 200 mA cm^?2 at low HER and OER overpotentials of 48, 132, 165 mV and 260, 350, 390 mV, respectively. The reported catalyst activation approach can be adapted for bifunctionalization of other transition metal dichalcogenides.