水热法制备α-FeOOH/MoS2纳米片复合物及其光催化性能

采用水热法成功制备了棒状α-FeOOH/MoS_2纳米片复合催化剂。运用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-Vis)和荧光发射光谱(PL)对复合催化剂的结构和形貌进行了表征。结果表明:成功制备了长度为500nm左右的纳米棒状α-FeOOH,其与MoS_2纳米片形成良好的复合结构。以亚甲基蓝为模拟污染物,研究复合催化剂在可见光照射下的光催化特性。结果显示,棒状α-FeOOH/MoS_2纳米片复合催化剂在120min内对亚甲基蓝的降解率为98%,其降解动力学常数是纯α-FeOOH的3倍。根据活性基捕获实验结果,提出了α-FeOOH与MoS_2纳米片形成异质结的Z型光催化机理。     

Al2O3基石油加氢脱硫催化剂研究现状与进展

综述了以三氧化二铝(Al_2O_3)为载体,负载Mo、Ni单一组元和Mo-Ni-W等复合组元,用于炼制石油加氢脱硫的催化剂的国内外研究现状与进展。全面总结了传统的浸渍法、混捏法、共沉淀法、离子交换法以及新型的微波-超声波法等催化剂合成方法,对Al_2O_3基催化剂的加氢脱硫性能进行了讨论,着重对催化剂合成过程中载体、活性组分、助剂(P、F、B等)和pH值对催化剂性能的影响进行了概述,在此基础上总结了Al_2O_3基加氢脱硫催化剂的不足之处,并展望了此类催化剂的发展方向与研究前景。     

Ni-Mo-Al_2O_3催化剂覆碳改性对其加氢脱硫性能的影响

在催化剂制备的不同阶段引入碳物质,制备3种覆碳改性的NiMo-Al_2O_3加氢脱硫催化剂,采用低温氮静态容量吸附-脱附法、X射线衍射、H_2程序升温还原和高分辨透射电子显微镜对3种催化剂进行表征,并考察催化剂的加氢脱硫性能。结果表明:引入碳物质能够提高催化剂的加氢脱硫活性;采用前覆碳法即在载体上负载活性组分前引入碳前躯物,或采用共浸渍法即将活性组分与碳前躯物共同浸渍到载体上制得的催化剂,都能够增加八面体Mo物种的数量;采用共浸渍法制得催化剂活性组分分散性良好,MoS_2纳米颗粒堆垛层数多,其脱硫率比未覆碳改性催化剂的高6.8%;采用前覆碳法制得催化剂的金属分散性良好,其脱硫率比未覆碳改性催化剂的高5.1%;与未覆碳改性的催化剂相比,采用后覆碳法即在已负载活性组分的Ni-Mo-Al_2O_3催化剂上引入碳前躯物制得催化剂的脱硫率提高程度不大。     

聚苯乙烯非均相催化加氢研究进展

随着国民经济发展和人民生活水平的不断提高,聚苯乙烯(PS)产品的多样化、专业化成为了市场竞争和用户需求的发展趋势。聚合物催化加氢工艺作为提高PS专用料性能的重要改性手段,近几年来已成为不饱和聚合物化学改性领域的研究热点。文中主要综述了国内外PS非均相催化加氢制备聚环己烷基乙烯(PCHE)体系中加氢工艺的改进、加氢催化剂的设计优化及反应机理研究的新进展。阐述了催化剂的结构设计、物化性能以及反应过程中传质扩散阻力等对PS加氢活性的影响,探讨了PS非均相催化加氢体系中的"Blocky"加氢机理,提出未来PS非均相加氢催化剂研究重点应该放在催化剂的结构设计上,既要保证聚合物分子与活性中心高接近性,又要实现在加氢体系中的传质扩散与催化剂载体上活性位点高分散的最佳平衡。同时,为进一步提高加氢催化剂的综合性能,需要加强对聚合物加氢反应机理和催化剂合成改性技术的基础性研究。     

MoS2/g-C3N4复合催化剂的制备及CdSe量子点敏化产氢性能研究

太阳能光催化分解水制氢被认为是从根本上解决能源与环境问题较为理想的途径之一。在以尿素为原料制得石墨相氮化碳(g-C_3N_4)的基础之上,采用简单的低温溶液反应法将二硫化钼(MoS_2)与石墨相氮化碳(g-C_3N_4)复合得到复合催化剂MoS_2/g-C_3N_4,并利用透射电子显微镜(TEM)、X射线衍射(XRD)、紫外-可见漫反射(DRS)、傅里叶变换红外光谱(FT-IR)和荧光光谱等对该复合光催化剂的组成、形貌和光物理性能进行了表征;进而以CdSe量子点为光敏剂,三乙醇胺(TEOA)为牺牲剂,构建了不含贵金属的三组分光催化产氢体系,并对体系pH值、CdSe量子点浓度等对产氢性能的影响进行了研究。结果表明:将MoS_2纳米颗粒负载到g-C_3N_4上可使g-C_3N_4的光催化产氢性能得到显著提高。当MoS_2负载量为7%(质量比)时,在最佳的条件下(pH=9.0,CdSe量子点的体积为25mL),最大产氢速率达到了141.74μmol·h-1,6h的产氢总量达到了212.61μmol。最后,结合荧光猝灭实验,推测了该体系的产氢机理。     

海泡石基金属氧化物复合材料的合成及其光催化性能研究进展

海泡石比表面积大、孔隙率高,且表面具有一定量的硅羟基基团,这可为其负载金属氧化物如TiO_2、ZnO、Fe_2O_3等提供更多的活性位点,因而它可以作为一种有效载体来制备具有较好吸附性和催化性的复合材料。主要介绍了海泡石基金属氧化物复合材料的不同制备方法,如溶胶-凝胶法、沉淀法、浸渍法;概述了其在提高比表面积、孔容积以及吸附性能等方面具有的优势;并综述了其在液相和气相光催化领域中的应用;介绍了其光催化性能的影响因素及最佳降解效果;最后对其作为生态环境材料的应用进行了前景展望。     

PW_(12)/MoS_2复合材料的制备及其光催化性能

首先采用水热法合成了球花状硫化钼(MoS_2),并将其与磷钨杂多酸(PW_(12))复合,采用SEM、XRD、EDS、FT-IR和UV-DRS等手段对复合材料(PW_(12)/MoS_2)进行了表征和分析。以刚果红为目标降解物,对PW_(12)/MoS_2的光催化性能进行研究,探究了催化剂用量对复合材料光催化降解性能的影响。研究结果证明:PW_(12)/MoS_2复合材料的带隙宽度为2.46 eV。与单独MoS_2相比,MoS_2和PW_(12)复合后,增强了光生电子-空穴的分离,光催化活性有明显提高。经过120min的光照后,对刚果红的降解效率为由38.70%提高到69.76%。此外,样品二次使用时,其光催化活性仍然能够保持63.87%。     

衬底位置对制备二维的MoS_2的影响

新型的二维层状材料凭借着其优异的机械、光学、电学等独特性能受到研究者广泛关注,二维层状材料如石墨烯、过渡金属硫族化合物等在柔性器件等领域具有潜在的应用前景,成为了现阶段研究热点之一;然而,应用的前提是高质量的二维材料大面积可控制备。利用化学气相沉积方法制备了二维的MoS_2,探讨了放置衬底的差异对合成二维的MoS_2的影响。结果表明,在其它相同的实验条件下,face-up和face-down的放置位置制备的MoS_2具有不同的形状、在衬底上的覆盖率不同;尽管如此,两种放置情况下,获得的单层的MoS_2具有类似的结构和荧光特性。研究结果对可控合成二维的MoS_2以及其它的TMDs均具有指导意义和参考价值。     

二硫化钼纳米片的制备及其光敏和气敏特性研究

利用高温硫化法制备了高纯度MoS_2纳米片。采用X射线衍射仪(XRD)、拉曼光谱仪(Raman spectrometer)、扫描电镜(SEM)和能谱仪(EDS)对MoS_2纳米片的物相、结晶质量以及形貌进行了表征,分析了反应温度对MoS_2纳米片的影响,并对MoS_2纳米片的光敏性和气敏特性进行了研究。结果表明,MoS_2纳米片对绿光响应度更高,红光次之,对甲醇和乙醇两种气体均有较高的灵敏度和响应/恢复速率,并对其气敏机理进行了讨论。     

储氢材料在催化加氢脱氢反应中应用的研究概况

简要地综述了储氢材料在催化加氢、脱氢反应中的应用以及用储氢材料制备催化剂的方法,如冶炼法、共沉淀法、机械合金化、急冷非晶化等。并介绍了为提高活性而采用的预氧化、氢化、酸浸等预处理方法。     

二维纳米片层结构MoS2和其改性材料的合成及在环境领域的应用

类石墨烯的二维纳米片层状MoS_2作为过渡金属硫化物材料家族的典型代表,由于其各方面独特的性能尤其是超薄的厚度和二维结构,已成为近些年材料的研究热点。独特的三明治结构使其具有良好的物理化学性质,MoS_2及其复合材料在催化、传感器、润滑等方面有广阔的前景。总结了国内外MoS_2的合成及其改性方法、性能和应用。针对社会发展过程中日益严重的环境污染问题,重点介绍利用其吸附和催化性能去除环境中污染物,并对其未来发展进行了展望。     

Anode materials from MoS2 and multilayered holey graphene for Li-ion batteries

Abstract

The ratio between the components determines the capacity of MoS₂/carbon materials in lithium-ion batteries (LIB). However, the structure of the carbon component and the synthesis conditions determine the amount of MoS₂ that can be efficiently used in each particular case. We study the influence of components ratio in MoS₂/multilayer holey graphene (HG) materials on the capacity in LIB. The synthesis was carried out by hot pressing of MoS₃ and HG mixtures at 600?°C and 100?bar. These synthesis conditions resulted in the decomposition of MoS₃ with the formation of MoS₂ nanocrystals. Optimal component distribution and better cycling performance, reaching 591 mAh g^?1 at a current density of 0.1?A g^?1 and 408 mAh g^?1 at 1?A g^?1, were found for MoS₂/HG containing 30?wt.% of MoS₂. An increase of the MoS₂ ratio led to a decrease of cycling stability and capacity of the material.     

Synthesis and characterization of flower-like MoS2 microspheres by a facile hydrothermal route

Flower-like MoS₂ microspheres with high purity were successfully synthesized via a facile hydrothermal route by adding sodium silicate as an additive. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD patterns showed that the MoS₂ microspheres had good crystallinity with well-stacked layered structure. TEM and SEM images showed that the MoS₂ microspheres had uniform sizes with mean diameter about 480 nm and were constructed with MoS₂ sheets with thickness of several nanometers. It was found that the possible precursor H₄SiMo₁₂O₄₀ obtained by sodium silicate reacting with sodium molybdate played a crucial role in the formation of the flower-like MoS₂ microspheres in our experiment. A possible formation mechanism of MoS₂ microspheres was preliminarily presented.     

Efficient Hydrogen Evolution Reaction Catalysis in Alkaline Media by All‐in‐One MoS2 with Multifunctional Active Sites

MoS₂ becomes an efficient and durable nonprecious‐metal electrocatalyst for the hydrogen evolution reaction (HER) when it contains multifunctional active sites for water splitting derived from 1T‐phase, defects, S vacancies, exposed Mo edges with expanded interlayer spacings. In contrast to previously reported MoS₂‐based catalysts targeting only a single or few of these characteristics, the all‐in‐one MoS₂ catalyst prepared herein features all of the above active site types. During synthesis, the intercalation of in situ generated NH₃ molecules into MoS₂ sheets affords ammoniated MoS₂ (A‐MoS₂) that predominantly comprises 1T‐MoS₂ and exhibits an expanded interlayer spacing. The subsequent reduction of A‐MoS₂ results in the removal of intercalated NH₃ and H₂S to form an all‐in‐one MoS₂ with multifunctional active sites mentioned above (R‐MoS₂) that exhibits electrocatalytic HER performance in alkaline media superior to those of all previously reported MoS₂‐based electrocatalysts. In particular, a hybrid MoS₂/nickel foam catalyst outperforms commercial Pt/C in the practically meaningful high‐current region (>25 mA cm^?2), demonstrating that R‐MoS₂‐based materials can potentially replace Pt catalysts in practical alkaline HER systems.     

Synthesis of MoS2 and MoO2 for their applications in H2 generation and lithium ion batteries: a review

Abstract

Scientists increasingly witness the applications of MoS₂ and MoO₂ in the field of energy conversion and energy storage. On the one hand, MoS₂ and MoO₂ have been widely utilized as promising catalysts for electrocatalytic or photocatalytic hydrogen evolution in aqueous solution. On the other hand, MoS₂ and MoO₂ have also been verified as efficient electrode material for lithium ion batteries. In this review, the synthesis, structure and properties of MoS₂ and MoO₂ are briefly summarized according to their applications for H₂ generation and lithium ion batteries. Firstly, we overview the recent advancements in the morphology control of MoS₂ and MoO₂ and their applications as electrocatalysts for hydrogen evolution reactions. Secondly, we focus on the photo-induced water splitting for H₂ generation, in which MoS₂ acts as an important co-catalyst when combined with other semiconductor catalysts. The newly reported research results of the significant functions of MoS₂ nanocomposites in photo-induced water splitting are presented. Thirdly, we introduce the advantages of MoS₂ and MoO₂ for their enhanced cyclic performance and high capacity as electrode materials of lithium ion batteries. Recent key achievements in MoS₂- and MoO₂-based lithium ion batteries are highlighted. Finally, we discuss the future scope and the important challenges emerging from these fascinating materials.     

Edge‐Terminated MoS2 Nanoassembled Electrocatalyst via In Situ Hybridization with 3D Carbon Network

Transition metal dichalcogenides, especially MoS₂, are considered as promising electrocatalysts for hydrogen evolution reaction (HER). Since the physicochemical properties of MoS₂ and electrode morphology are highly sensitive factor for HER performance, designed synthesis is highly pursued. Here, an in situ method to prepare a 3D carbon/MoS₂ hybrid catalyst, motivated by the graphene ribbon synthesis process, is reported. By rational design strategies, the hybrid electrocatalysts with cross‐connected porous structure are obtained, and they show a high HER activity even comparable to the state‐of‐the‐art MoS₂ catalyst without appreciable activity loss in long‐term operations. Based on various physicochemical techniques, it is demonstrated that the synthetic procedure can effectively guide the formation of active site and 3D structure with a distinctive feature; increased exposure of active sites by decreased domain size and intrinsically high activity through controlling the number of stacking layers. Moreover, the importance of structural properties of the MoS₂‐based catalysts is verified by controlled experiments, validating the effectiveness of the designed synthesis approach.     

三维花状MoS2锌离子电池正极材料的设计构筑及其储能机制研究

采用水热法设计构筑三维花状二硫化钼,并利用XRD、SEM、RAMAN、TG等测试方法对产物的结构和形貌进行了表征,进而作为正极材料组装成锌离子电池并对其进行电化学测试分析,在充放电电压区间为0.2~1.2V、电流密度为1.0A/g条件下,首次放电比容量可达63.9 mAh/g,100次循环后其放电比容量保持在53.6mAh/g,容量保持率为83.9%。较高的比容量和循环稳定性使MoS_2成为有前景的锌离子电池正极材料之一。     

Faceted MoS2 nanotubes and nanoflowers

A simple synthesis of novel faceted MoS₂ nanotubes (NTs) and nanoflowers (NFs) starting from molybdenum oxide and thiourea as the sulphur source is reported. The MoS₂ nanotubes with the faceted morphology have not been observed before. Further the as-synthesized MoS₂ nanotubes have high internal surface area. The nanostructures have been characterized by a variety of electron microscopy techniques. It is expected that these MoS₂ nanostrutures will find important applications in energy storage, catalysis and field emission.     

RF plasma modified W5O14 and MoS2 hybrid nanostructures and photovoltaic properties

Modification of W₅O₁₄ and MoS₂ nanostructures was carried out using 3,4-ethylenedioxythiophene monomer in a capacitively coupled, RF rotating plasma reactor. Raman spectroscopy and X-ray diffraction (XRD) measurements were used for structural characterization. The surface morphologies of nanomaterials were investigated using transmission electron microscopy. Polymer coated (W₅O₁₄/PEDOT, MoS₂/PEDOT) and untreated (W₅O₁₄, MoS₂) nanostructures were used as the counter electrode for dye-sensitized solar cells. Photovoltaic performances of W₅O₁₄/PEDOT and MoS₂/PEDOT hybrid nanostructures were higher than those of W₅O₁₄ and MoS₂ inorganic nanostructures. Our results indicate that plasma polymer coated W₅O₁₄ and MoS₂ nanostructures of the device for cathode increase both its fill factor and its energy conversion efficiency.     

Hydrothermal synthesis and characterization of MoS2 nanorods

MoS₂ nanorods were successfully synthesized via hydrothermal method by adding sillicontungstic acid as an additive. The products were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectrum (XPS) and field-emission scanning electron microscopy (FESEM). XRD pattern result indicated that the as-prepared sample can be indexed to a mixture of hexagonal and rhombohedral phase MoS₂. XPS showed that the nanorods were only composed of Mo and S with atomic ratio of 1:2. FESEM images revealed that the MoS₂ rods had uniform sizes with mean diameters of about 20-50 nm and lengths of 400-500 nm. It was found that the addition of sillicontungstic acid played a crucial role in the formation of the rod-like MoS₂ in our experiment. The possible formation mechanism of MoS₂ nanorods is also discussed.