碳化钼基析氢反应电催化剂的制备及改性研究进展

碳化钼(Mo₂C)因其与铂(Pt)相似的d带电子结构、宽pH适用性、易于合成、低成本等优势，成为一种很有前途的电催化剂。然而，纯Mo₂C存在导电性差、界面反应动力学慢、Mo-H结合能太强等缺陷。近年来，许多研究报道了改性Mo₂C基催化剂来提升其电催化析氢性能，基于此，综述了Mo₂C常用的制备工艺以及提高Mo₂C析氢性能的各种不同改性策略，深入分析了不同改性方式对Mo₂C析氢性能提高的内在原因。最后，提出了Mo₂C基电催化剂目前面临的挑战和未来的发展方向。     

负载Pt纳米颗粒的掺氮碳化钼微球催化电解水析氢

电解水制氢是极具发展应用前景的绿色技术,使用低成本碳材料负载贵金属作为催化剂基底,是减小析氢催化剂贵金属负载量和优化其性能的有效手段。采用配位聚合法,通过调控pH得到了由纳米片自组装形成的具有高比表面积的前驱体微球,再通过离子交换和高温焙烧将Pt纳米颗粒均匀负载在氮掺杂碳化钼表面,制备出了Pt/N-Mo₂C NFs。因Pt纳米颗粒具有多层级结构的N-Mo₂C上的高度分散以及Pt与N-Mo₂C基底之间的协同作用,它展现出十分优异的析氢性能。Pt/N-Mo₂C NFs拥有较低的过电位(44 mV/η₁₀和137 mV/η₁₀₀),和Tafel斜率为46.2 mV/dec,同时具有良好的稳定性。研究结果对于设计低负载量的贵金属催化剂具有一定的借鉴意义。     

MoS2/MoxN异质结构的制备及其电催化析氢性能研究

二硫化钼纳米片(MoS₂)是一种有望取代贵金属材料、非常有前景的电催化析氢材料。MoS₂不足在于导电性较差，析氢反应(HER)能垒较高。为了克服这一缺点，我们引入制备简单、导电性良好的Mo₂N作为基体。通过水热法，将MoS₂纳米片均匀生长在Mo₂N颗粒表面，一方面增加了材料导电性，另一方面MoS₂与Mo₂N形成MoS₂/Mo_xN异质结构有效增强水分子的解吸，从而提高HER性能。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、电化学工作站对MoS₂/Mo_xN进行结构、形貌以及性能的表征。实验结果表明，MoS₂纳米片均匀生长在Mo₂N颗粒表面，形成异质结构，水热12 h所得材料性能最佳。以MoS₂/Mo_xN作为工作电极，碳棒与Ag...     

MoS2/MoxN异质结构的制备及其电催化析氢性能研究

二硫化钼纳米片(MoS₂)是一种有望取代贵金属材料、非常有前景的电催化析氢材料。MoS₂不足在于导电性较差，析氢反应(HER)能垒较高。为了克服这一缺点，我们引入制备简单、导电性良好的Mo₂N作为基体。通过水热法，将MoS₂纳米片均匀生长在Mo₂N颗粒表面，一方面增加了材料导电性，另一方面MoS₂与Mo₂N形成MoS₂/Mo_xN异质结构有效增强水分子的解吸，从而提高HER性能。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、电化学工作站对MoS₂/Mo_xN进行结构、形貌以及性能的表征。实验结果表明，MoS₂纳米片均匀生长在Mo₂N颗粒表面，形成异质结构，水热12 h所得材料性能最佳。以MoS₂/Mo_xN作为工作电极，碳棒与Ag...     

MoS2/MoxN异质结构的制备及其电催化析氢性能研究

二硫化钼纳米片(MoS₂)是一种有望取代贵金属材料、非常有前景的电催化析氢材料。MoS₂不足在于导电性较差，析氢反应(HER)能垒较高。为了克服这一缺点，我们引入制备简单、导电性良好的Mo₂N作为基体。通过水热法，将MoS₂纳米片均匀生长在Mo₂N颗粒表面，一方面增加了材料导电性，另一方面MoS₂与Mo₂N形成MoS₂/Mo_xN异质结构有效增强水分子的解吸，从而提高HER性能。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、电化学工作站对MoS₂/Mo_xN进行结构、形貌以及性能的表征。实验结果表明，MoS₂纳米片均匀生长在Mo₂N颗粒表面，形成异质结构，水热12 h所得材料性能最佳。以MoS₂/Mo_xN作为工作电极，碳棒与Ag...     

碳化钼电解水析氢催化剂的性能调控研究进展

氢气作为一种绿色、可持续的能源,有望代替传统的化石能源。电解水产氢是氢能可持续发展的理想途径。发展非贵金属电催化剂,提高电催化析氢反应(HER)效率,成为目前面临的主要问题。碳化钼因具有较好的电催化析氢活性和优异的稳定性,得到了广泛的关注。本文综述了近几年碳化钼电催化剂电解水产氢的研究进展,重点分析了提高其电催化析氢性能的一些方法,并对碳化钼的性能调控研究进行了展望。     

多维镍钴硫化物异质结电催化剂用于高效全水解（英文）

异质结构工程在高效全解水催化剂方面具有突出的应用前景.然而,生产廉价高效的双功能电催化剂仍然是一个巨大的挑战.因此,我们受构树启发,通过一种简单的方法在泡沫镍基体上合成了高催化活性和稳定性的Co₉S₈@CoNi₂S₄/NF异质结.该过程包括NiCo层状双氢氧化物在泡沫镍基体上的原位生长和原位衍生ZIF-67,并伴随S原子掺杂.所获得的Co₉S₈@CoNi₂S₄/NF多维度异质结包括一维纳米线、二维纳米片和纳米颗粒.优化的Co₉S₈@CoNi₂S₄/NF中硫含量为10%,在1.0 mol L^-1KOH溶液中,电流密度为10 mA cm^-2时,具有优异的电催化活性,其析氢和析氧过电位分别为68和170 mV,优于最近报道的过渡金属基电催化剂.该催化剂优异的催化性能主要归因于CoNi     

Co-Mn掺杂碳气凝胶的制备与性能

为探究不同碳化温度对Co-Mn掺杂碳气凝胶（Co-Mn/CA）电催化析氢性能的影响,以资源丰富且可再生的木质纤维素为碳源、四水乙酸钴为钴源、四水乙酸锰为Mn源,通过水热法制备出Co-Mn/CA。研究发现,纤维素气凝胶碳化后表面形貌发生改变,由片层结构转变为多孔结构,使其活性位点数量增多,电催化析氢活性增加。通过XRD和N₂吸-脱附对其结构进行了表征处理分析,结果表明,经碳化处理后的CA产物以无定型碳为主,经900℃碳化处理后的CA（CA-900）比表面积和总孔隙体积均为最大,分别为958 m2g-1和0.33 cm3·g-1。电化学性能测试表明,Co-Mn/CA-900表现出最好的电催化析氢反应（HER）催化活性,在1 mol/L KOH电解液中、50 mA·cm-2的电流密度下,具有175 mV的过电势,经过10 h的计时电位测试,压降仅为7%,表现出较好的电催化析氢稳定性。      

单原子铁在硫化钼上的组装及电催化析氢

贵金属Pt具有最高的析氢活性，但其高昂的价格限制了大面积推广应用。因此，研究开发高活性、低成本的析氢电催化材料，对发展氢能产业具有重要意义。利用二步水热反应法成功制备单原子铁-硫化钼(Fe-MoS₂)电催化材料，并采用X-射线粉末衍射(XRD)、高角环形暗场扫描透射电子显微镜(HAADF-STEM)成像技术、能量色散X射线光谱(EDX)、电子能谱测定(XPS)对Fe-MoS₂进行了表征。XRD结果表明，所制备Fe-MoS₂样品的粉末衍射曲线与晶态2H-MoS₂的标准卡(JCPDS 37-1492)相一致，表明Fe-MoS₂与2H-MoS₂具有相同的晶型结构；球差电镜分析表明，铁单原子均匀分布于MoS₂表面；EDX与XPS分析进一步表明铁单原子存在于MoS₂结构中。采用线性扫描伏安(LSV)法研究了Fe-MoS₂的析氢性能。结果表明，最佳条件下制备的Fe-MoS₂,其析氢...     

二维碳化钼纳米材料的制备及其析氢催化性能研究

电解水制氢是目前重要的制氢技术之一,而经济、高效的析氢反应催化剂是这一技术实现工业化的关键之一。简要综述了近3年来二维(2D)碳化钼的主要制备方法及其对电催化性能的影响,并分析了现有制备方法的优势和不足,展望了新型二维碳化钼作为析氢催化材料在电解水中的应用前景。     

Polymer-filler derived Mo2C ceramics

Manufacturing, microstructure and properties of novel reaction bonded Mo₂C materials derived from polymer/reactive filler mixtures were investigated. Mo powder was used as a filler to react with carbon bearing decomposition products of poly(methyl- and phenysiloxanes) during pyrolysis in nitrogen atmosphere. Microcrystalline composites with the filler reaction products Mo₃C, Mo₃Si, Mo₅Si₃ embedded in a silicon oxycarbide glass matrix could be formed with complex geometry owing to near net shape polymer/ceramic conversion. Depending on the precursor composition and pyrolysis conditions, ceramic hard materials with a density up to 97% theoretical density, a hardness of 10 GPa, a Young’s Modulus of 250 GPa, a fracture toughness of 5 MPam^1/2 and a flexural strength of 330 MPa were obtained.     

MoS2/Co9S8/MoC heterostructure connected by carbon nanotubes as electrocatalyst for efficient hydrogen evolution reaction

High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction (HER),but developing such materials is challenging.Herein,a simple strategy was designed to build a MoS2/Co9S8/MoC@CNT-N (MCM@CNT-N) heterostructure with a large number of interfaces.Regarding the HER,the synthesized MCM@CNT-N heterostructure catalyst showed high efficiency and stable electrocatalytic performance,with a low overpotential of 174.2 mV and a small Tafel slope of 84.7 mV dec-1 at a current density of 10 mAcm-2 in 0.5 M H2SO4.In addition to the function of heterojunctions,the excellent activity is also attributed to the introduction of Co and N atoms and the formation of carbon nanotubes.This work provides a new approach to build efficient and low-cost electrocatalysts for electrochemical reactions.     

Growth kinetics of Mo3Si layer in the Mo5Si3/Mo diffusion couple

The diffusion processes and growth kinetics of the Mo₃Si silicide layer occurring at annealing the Mo₅Si₃/Mo diffusion couple between 1180 and 1800 °C were studied by electrothermography. The experimental results are supplemented with calculations on the behaviour of the initial Mo₅Si₃/Mo diffusion couple on the basis of the reaction diffusion model describing the transformation of the Mo₅Si₃ layer into a Mo₃Si one. The values of the parabolic growth constant for Mo₃Si layer were determined and the silicon diffusion coefficient in the Mo₃Si phase was calculated: D = 0.165 exp[(− 247 ± 10) / RT], cm²/s, where the activation energy is expressed in terms of kJ/mol.     

Interfacial Engineering of W2N/WC Heterostructures Derived from Solid-State Synthesis: A Highly Efficient Trifunctional Electrocatalyst for ORR,OER, and HER

To meet the practical demand of overall water splitting and regenerative metal–air batteries, highly efficient, low-cost, and durable electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are required to displace noble metal catalysts. In this work, a facile solid-state synthesis strategy is developed to construct the interfacial engineering of W₂N/WC heterostructures, in which abundant interfaces are formed. Under high temperature (800 °C), volatile CN_x species from dicyanodiamide are trapped by WO₃ nanorods, followed by simultaneous nitridation and carbonization, to form W₂N/WC heterostructure catalysts. The resultant W₂N/WC heterostructure catalysts exhibit an efficient and stable electrocatalytic performance toward the ORR, OER, and HER, including a half-wave potential of 0.81 V (ORR) and a low overpotential at 10 mA cm⁻² for the OER (320 mV) and HER (148.5 mV). Furthermore, a W₂N/WC-based Zn–air battery shows outstanding high power density (172 mW cm⁻²). Density functional theory and X-ray absorption fine structure analysis computations reveal that W₂N/WC interfaces synergistically facilitate transport and separation of charge, thus accelerating the electrochemical ORR, OER, and HER. This work paves a novel avenue for constructing efficient and low-cost electrocatalysts for electrochemical energy devices.     

Microstructure and properties of MoSi2–MoB and MoSi2–Mo5Si3 molybdenum silicides

MoSi₂-based intermetallics containing different volume fractions of MoB or Mo₅Si₃ were fabricated by hot-pressing MoSi₂, MoB, and Mo₅Si₃ powders in vacuum. Both classes of alloys contained approximately 5 vol.% of dispersed silica phase. Additions of MoB or Mo₅Si₃ caused the average grain size to decrease. The decrease in the grain size was typically accompanied by an increase in flexure strength, a decrease in the room temperature fracture toughness, and a decrease in the hot strength (compressive creep strength) measured around 1200 °C, except when the Mo₅Si₃ effectively became the major phase. Oxidation measurements on the two classes of alloys were carried out in air. Both classes of alloys were protected from oxidation by an in-situ adherent scale that formed on exposure to high temperature. The scale, although not analyzed in detail, is commonly recognized in MoSi₂ containing materials as consisting mostly of SiO₂. The MoB containing materials showed an increase in the scale thickness and the cyclic oxidation rate at 1400 °C when compared with pure MoSi₂. However, in contrast with the pure MoSi₂ material, oxidation at 1400 °C began with a weight loss followed by a weight gain and the formation of the protective silica layer. The Mo₅Si₃ containing materials experienced substantial initial weight losses followed by regions of small weight changes. Overall, the MoB and Mo₅Si₃ additions to MoSi₂ tended to be detrimental for the mechanical and oxidative properties.     

碳基硫化钼电催化制氢催化剂的研究进展

金属铂是目前最高效的电催化制氢催化剂,但由于铂存在高成本、低储量等缺点,难以适合广泛的工业应用。因此,寻找低成本、高储量的替代电催化制氢催化剂成为未来发展的方向。二硫化钼因具有制氢活性较高、储量丰富、易于制备等优势越来越受到关注。二硫化钼的制氢活性主要取决于暴露的催化活性位数量和导电性。因此,利用纳米碳材料的高导电性和高比表面积来提高二硫化钼的导电性和制氢催化活性位的数量,是制备高活性二硫化钼电催化剂的重要策略之一。重点介绍了二硫化钼电催化制氢的基本原理,以及采用不同碳材料,如石墨烯、氧化石墨烯、碳纳米管等,改进二硫化钼电催化制氢性能的合成方法、催化效果及反应机理。最后,展望了利用碳材料辅助制备高活性、低成本电催化制氢催化剂的前景。     

Mechanical properties of Mo5Si3 intermetallics as a function of composition

A solubility range of 2.1 at.% Si at 1600 °C in Mo₅Si₃ was measured by energy dispersive spectrometry (EDS) in a SEM on samples containing the second phases Mo₃Si and MoSi₂, respectively. Of the three methods for elemental analysis used in this work, i.e. bulk chemical analysis, EDS, and Rietveld refinement of neutron powder diffraction data, it is concluded that EDS yields an underestimation of Si-content in Mo₅Si₃ compared to bulk chemical analysis. As a result, the homogeneity range of Mo₅Si₃ is displaced to lower Si-content compared to the Mo-Si binary phase diagram. Both hardness and toughness of Mo₅Si₃ displayed their highest values for the composition closest to stoichiometry. The single-phase sample contained Mo vacancies according to Rietveld refinement, which is in good agreement with the results of chemical analysis as these show a slight Mo-deficiency.     

双A层MAX相Mo2Ga2C的热压烧结研究

本工作采用真空热压烧结的方法, 研究Mo₂Ga₂C粉体的烧结性能, 制备致密的Mo₂Ga₂C块体材料, 并且表征所制备材料的微观结构。实验发现750 ℃是合适的烧结温度, 过高的烧结温度(850 ℃)会导致样品分解, 主要产物为Mo₂C。在750 ℃烧结过程中, 随着烧结时间的延长, 样品的晶粒没有明显长大, 但是样品内部空隙显著变小, 内部织构增强, 相对密度明显提高。因为Mo₂Ga₂C晶体的片状结构, 热压烧结过程中, 部分片状晶粒会偏转, 导致烧结样品的多数晶粒的(00l)晶面会倾向垂直于热压方向。在750 ℃烧结8 h, 可以得到几乎完全致密(相对密度98.8%)的Mo₂Ga₂C块体材料。     

Mo_2C改性C/C-Cu复合材料的组织及载流摩擦磨损性能

采用熔盐法在低密度炭/炭(C/C)坯体内孔表面制备了Mo_2C涂层,然后通过无压熔渗制备了C/C-Cu复合材料,研究了C/C-Cu复合材料的组织结构及载流摩擦磨损性能。结果表明:熔融Cu可自发渗入制备了Mo_2C内涂层的C/C坯体,复合材料中Cu相与C/C坯体形成相互贯穿的连通网络结构,Mo_2C涂层与Cu和热解炭(PyC)间均有良好的界面结合,反应生成Mo_2C过程中的催化石墨化及应力石墨化共同作用使C/C-Cu复合材料中Mo_2C涂层附近PyC的有序度提高。随载荷增大,C/C-Cu复合材料的摩擦系数逐渐降低,体积磨损率增大,而对偶的质量损失逐渐降低;载荷较大时材料磨损表面被摩擦膜覆盖的面积增大,但因粘着磨损摩擦膜的粗糙程度提高。材料磨损过程中还发生了氧化磨损,且载荷增大磨损表面O含量提高。     

Interface engineering of Co3O4---SmMn2O5 nanosheets for efficient oxygen reduction electrocatalysis

Interface engineering is an efficient strategy to modify electronic structure and further improve electrocatalytic activity. Herein, crystalline/amorphous heterostructured Co₃O₄–SmMn₂O₅ nanosheets (Co₃O₄–SMO NSs) have been synthesized by coupling of SMO (electron acceptor) with higher Fermi-level Co₃O₄ (electron donor), via a one-step hydrothermal method followed by calcination. The resulting Co₃O₄–SMO NSs display higher half-wave potential and specific activity than those of pure SMO or Co₃O₄. In addition, Co₃O₄–SMO NSs exhibit superior stability and methanol tolerance. The crystalline/amorphous heterostructure and the electron interaction between SMO and Co₃O₄ result in interfacial charge transfer. This leads to more active valence states and more oxygen vacancies, optimizing the adsorption energy of O species and expediting electron migration, thus boosting oxygen reduction reaction (ORR) catalytic performance. This study provides a promising strategy to design efficient ORR electrocatalysts by interfacial engineering.