超级电容器中的二维材料

以石墨烯为代表的具有层状结构的二维材料因具有大比表面积等特性成为超级电容器电极材料的热门候选.文章着眼于针对诸如石墨烯、过渡金属二硫族化合物、过渡金属碳/氮化物、层状过渡金属氧化物/氢氧化物等二维材料在超级电容器领域应用的研究,尝试总结了其制备方法、产物形貌特征以及作为电极的性能等,并对这一领域的未来发展和面临的挑战提出了看法与预测.     

二维材料MXene的制备与电学性能研究进展

具有层状结构的二维过渡金属碳/氮化物材料(MXene)因其优良的导电性、良好的亲水性以及丰富的表面化学结构得到了大部分研究者的关注.着眼于MXene的先进制备方法及过程展开综述,同时综述了其在电学方面(包括超级电容器,电池材料和电催化)的研究进展.在MXene超级电容器中相较于普通水系电解液,有机电解液或离子电解液往往...     

二维MXene材料在超级电容应用的研究进展

二维过渡金属碳/氮化物(MXene)具有类石墨烯的结构,微观上呈现片层状和多种表面基团,因此具有良好的导电性、离子传输和高亲水性能,并且成为超级电容器的理想电极材料。但MXene层与层容易坍塌、堆叠与官能团的存在,不利于作为电极材料的性能。通过热处理、离子插层和与碳复合等方法提高其电化学性能拥有巨大的应用前景。首先总结了MXene材料的制备方法,然后概述了表面改性和结构优化等对MXene超级电容器的电化学性能的影响,展望了MXene材料在超级电容器上的研究前景。     

新型超级电容器电极材料

超级电容器以其高功率、长周期使用寿命、环保等独特性能受到人们的广泛关注。决定超级电容器电荷存储的最关键因素是电极材料的特性。首先简要介绍了电容器的电荷储存机理。其次详细介绍了金属有机骨架材料(MOFs)、共价有机骨架材料(COFs)、二维过渡金属碳(氮)化物(MXenes)、金属氮化物(MN)、黑磷(BP)和有机分子电极材料等有望获得高能量密度和功率密度的新兴电极材料,以及最新制作的对称/非对称超级电容器的能量、电容、功率、循环性能和倍率性等参数。研究表明,COFs有望成为新一代廉价、绿色、可持续、多功能的储能装置的有机电极候选材料,其电化学性能仍有很大的提高空间。重点介绍了MOFs、COFs、MN、BP及近年来新型有机电极材料在超级电容器中的应用。最后,对超级电容器未来的发展和关键技术的挑战进行了展望。     

新型二维层状材料MXene在超级电容器上的研究与应用进展

二维过渡族金属碳化物/氮化物(MXene)是二维材料家族的新兴成员,通过液相刻蚀等方法移除MAX相的A层得来。独特的二维结构及表面化学组成,使其表现出了良好的金属导电性、亲水性、优异的柔韧性及离子可插层性,在超级电容器研究与应用领域展现了巨大的潜力,受到了广泛关注。但是MXene仍存在诸多问题。首先,片层容易发生堆叠,极大降低了材料与电解液的有效接触面面积;在刻蚀过程中,化学键断裂处具有较高的活性,极易反应生成表面基团,表面基团的存在对电化学性能有较大影响;合成路线中强腐蚀液的使用也会造成安全、环境等诸多问题。对MXene的结构、性质、制备方法等进行了简要概述,总结了近年来MXene在超级电容器领域的研究进展和方向,旨在从中发现解决MXene诸多问题思路,以期为制备高性能MXene超级电容器电极材料提供参考。     

原位自生法制备高性能氧化物/纳米多孔金属复合电极

正超级电容器具有功率大、充放电速度快和循环稳定性高等优点,但能量密度低一直是限制其更广泛应用的主要障碍。提高超级电容器能量密度的关键是开发高性能电极材料。以廉价过渡金属氧化物为代表的赝电容材料以其高的理论比电容吸     

类石墨烯硫族化合物纳米材料及其在能源领域中的应用

2004年以来,以石墨烯为代表的新型二维纳米材料引起了全球范围内的研究热潮,在光电子、生物、能源等领域展现出了巨大的应用潜力。过渡金属硫族化合物因平面内结合力较强、平面外结合力较弱以致可以将其剥离成单个细胞厚度的二维层状纳米材料,且该材料具备类石墨烯物理化学性质而被誉为"无机石墨烯"。关于二维过渡金属硫族化合物纳米材料的研究已有多年,众多研究表明,因其具有独特的结构和特性,在光电器件、催化及能源存储领域有着广阔的应用前景。基于该领域研究的最新进展,综述了二维过渡金属硫族化合物纳米材料在能源领域中的应用,并对目前相关研究领域的发展趋势进行了总结和展望。     

三维石墨烯及其复合材料的制备及在超级电容器中的研究进展

三维(3D)石墨烯及其复合材料具有柔韧性好、比表面积大、功率密度高、力学性能稳定以及离子传输迅速等优良性能,成为材料科学领域备受关注的材料。概述了三维石墨烯材料的基本性质和性能,并对其多元复合材料的制备方法以及在超级电容器储能材料方面的应用研究进展进行了评述。三维(3D)石墨烯常用的制备方法有自组装法、模板导向法和3D打印法等,通过对制备方法进行改进,可以有效调控三维材料的多孔结构、孔径、柔韧性和电子传递速度等性能。三维(3D)石墨烯与过渡金属化合物及导电聚合物复合而成的多元复合物在超级电容器电极材料方面表现出广阔的应用前景。     

碳化钛/椴木多孔碳复合材料用于超级电容器性能的研究

碳化钛作为一种新兴的层状二维材料具有一些独特的物理化学性质, 近年来引起了科研工作者广泛的注意。它是由化学选择性刻蚀的方法获得, 在电化学如锂电池, 超级电容器等领域展现出极好的应用前景。目前研究中碳化钛的电极往往活性物质负载量较低, 导致面容量不佳, 从而限制了其在大规模生产中的应用。本工作受自然界中椴木结构的启发, 利用其多孔道、孔道弯曲度低、导电性好、低价环保等特点, 将碳化钛与椴木活性炭复合, 获得了一种具有高面电容且稳定的超级电容器, 该电容器在2 mV/s的扫速下具有1983 mF/cm ²的面容量, 同时活性材料负载量可以达到17.9 mg/cm ²。本研究为后续利用自然界构型材料与功能材料的复合提供了一定的借鉴。     

可拉伸超级电容器碳基复合电极材料的研究进展

随着便携式和可穿戴电子产品的发展,人们对柔性储能设备的需求越来越迫切。常用的储能设备有锂离子电池、超级电容器等。与锂离子电池相比,超级电容器具有更快的充放电速度、更高的循环稳定性能和更大的比电容等优点。但传统的超级电容器在受到拉伸、压缩等外力作用时,存储功能难免下降甚至丧失。因此,可拉伸超级电容器引起了研究者们的关注。电极是可拉伸超级电容器的重要组成部分,人们通过制备性能优异的电极材料或设计能够抗压缩、拉伸、扭曲等高强度机械力的电极结构来提高电极的电化学性能和力学性能。碳纳米管、石墨烯、碳纤维和碳气凝胶等碳材料属于双电层电容器电极材料,它们虽然比表面积大、循环稳定性强,但仍存在低比电容、低能量密度等缺点。其中,石墨烯更是面临因堆叠团聚而导致的储能性能降低的问题。于是,人们在将碳材料与其他电极材料结合制备碳基可拉伸复合电极材料方面做了许多尝试。高比电容的赝电容电极材料、大比表面积的过渡金属硫化物或高导电性的金属纳米线,都已被发现能够与某些碳材料产生协同互补,形成的碳基复合电极在比电容、循环稳定性和力学性能方面相比单种碳电极材料有明显提高。本文在对比介绍用作可拉伸超级电容器的各种碳材料的优势与不足的基础上,综述了近年来广泛应用于可拉伸超级电容器的碳基复合电极材料的研究进展。     

Potential 2D Materials with Phase Transitions: Structure,Synthesis, and Device Applications

Layered materials with phase transitions, such as charge density wave (CDW) and magnetic and dipole ordering, have potential to be exfoliated into monolayers and few‐layers and then become a large and important subfamily of two‐dimensional (2D) materials. Benefitting from enriched physical properties from the collective interactions, long‐range ordering, and related phase transitions, as well as the atomic thickness yet having nondangling bonds on the surface, 2D phase‐transition materials have vast potential for use in new‐concept and functional devices. Here, potential 2D phase‐transition materials with CDWs and magnetic and dipole ordering, including transition metal dichalcogenides, transition metal halides, metal thio/selenophosphates, chromium silicon/germanium tellurides, and more, are introduced. The structures and experimental phase‐transition properties are summarized for the bulk materials and some of the obtained monolayers. In addition, recent experimental progress on the synthesis and measurement of monolayers, such as 1T‐TaS₂, CrI₃, and Cr₂Ge₂Te₆, is reviewed.     

A Simple,General Synthetic Route toward Nanoscale Transition Metal Borides

Most nanomaterials, such as transition metal carbides, phosphides, nitrides, chalcogenides, etc., have been extensively studied for their various properties in recent years. The similarly attractive transition metal borides, on the contrary, have seen little interest from the materials science community, mainly because nanomaterials are notoriously difficult to synthesize. Herein, a simple, general synthetic method toward crystalline transition metal boride nanomaterials is proposed. This new method takes advantage of the redox chemistry of Sn/SnCl₂, the volatility and recrystallization of SnCl₂ at the synthesis conditions, as well as the immiscibility of tin with boron, to produce crystalline phases of 3d, 4d, and 5d transition metal nanoborides with different morphologies (nanorods, nanosheets, nanoprisms, nanoplates, nanoparticles, etc.). Importantly, this method allows flexibility in the choice of the transition metal, as well as the ability to target several compositions within the same binary phase diagram (e.g., Mo₂B, α‐MoB, MoB₂, Mo₂B₄). The simplicity and wide applicability of the method should enable the fulfillment of the great potential of this understudied class of materials, which show a variety of excellent chemical, electrochemical, and physical properties at the microscale.     

聚合物/过渡金属氧化物纳米复合材料在电致变色性能上的研究进展

聚合物/过渡金属氧化物纳米复合材料是近年来引人注目的一种新型功能性材料.介绍了这类材料的种类和制备方法,综述了聚合物/过渡金属氧化物的电致变色性能,探讨了聚合物/过渡金属氧化物的电致变色机理.     

PtTe2‐Based Type‐II Dirac Semimetal and Its van der Waals Heterostructure for Sensitive Room Temperature Terahertz Photodetection

Recent years have witnessed rapid progresses made in the photoelectric performance of two‐dimensional materials represented by graphene, black phosphorus, and transition metal dichalcogenides. Despite significant efforts, a photodetection technique capable for longer wavelength, higher working temperature as well as fast responsivity, is still facing huge challenges due to a lack of best among bandgap, dark current, and absorption ability. Exploring topological materials with nontrivial band transport leads to peculiar properties of quantized phenomena such as chiral anomaly, and magnetic‐optical effect, which enables a novel feasibility for an advanced optoelectronic device working at longer wavelength. In this work, the direct generation of photocurrent at low energy terahertz (THz) band at room temperature is implemented in a planar metal–PtTe₂–metal structure. The results show that the THz photodetector based on PtTe₂ with bow‐tie‐type planar contacts possesses a high photoresponsivity (1.6 A W^?1 without bias voltage) with a response time less than 20 µs, while the PtTe₂–graphene heterostructure‐based detector can reach responsivity above 1.4 kV W^?1 and a response time shorter than 9 µs. Remarkably, it is already exploitable for large area imaging applications. These results suggest that topological semimetals such as PtTe₂ can be ideal materials for implementation in a high‐performing photodetection system at THz band.     

过渡金属离子掺杂对磷酸铁锂性能的影响

以碳酸锂、草酸亚铁、磷酸二氢铵、葡萄糖为原料,添加不同的过渡金属乙酸盐(乙酸锰、乙酸钴、乙酸镍、乙酸锌),在氩气保护下采用高温固相法制备LiFePO4/C复合材料.采用X射线衍射、扫描电子显微镜、同步热分析、恒电流充放电、电化学阻抗、循环伏安等方法研究掺杂金属离子及掺杂量对LiFePO4/C晶体结构和电化学性能的影响.结果表明,LiFe0.9M0.1PO4/C(M=Mn、Co、Ni、Zn)样品的晶体结构均与橄榄石型LiFePO4相同.掺杂过渡金属阳离子可以提高LiFeP04/C的还原电位,降低氧化电位,缩小氧化还原峰间距,提高化学反应的可逆性.掺杂后的样品在5C下的放电性能较好,以LiFe0.9Ni0.1PO4/C的放电容量最高,达到89 mAh/g.     

Characterization of Edge Contact: Atomically Resolved Semiconductor–Metal Lateral Boundary in MoS2

Despite recent efforts for the development of transition‐metal‐dichalcogenide‐based high‐performance thin‐film transistors, device performance has not improved much, mainly because of the high contact resistance at the interface between the 2D semiconductor and the metal electrode. Edge contact has been proposed for the fabrication of a high‐quality electrical contact; however, the complete electronic properties for the contact resistance have not been elucidated in detail. Using the scanning tunneling microscopy/spectroscopy and scanning transmission electron microscopy techniques, the edge contact, as well as the lateral boundary between the 2D semiconducting layer and the metalized interfacial layer, are investigated, and their electronic properties and the energy band profile across the boundary are shown. The results demonstrate a possible mechanism for the formation of an ohmic contact in homojunctions of the transition‐metal dichalcogenides semiconductor–metal layers and suggest a new device scheme utilizing the low‐resistance edge contact.     

二元及三元过渡金属氧化物的制备及其电化学应用研究进展

二元及三元过渡金属氧化物由于其优异的物理和化学特性,在电化学领域得到了广泛的应用。本文主要介绍了不同元素组成的二元及三元过渡金属氧化物,以及通过不同制备方法得到的空心球状、管状、片状、立方体、棒状、针状、伞形等多种不同形貌的二元及三元过渡金属氧化物;总结了二元及三元过渡金属氧化物在超级电容器、锂离子电池和传感器领域中表现出的优异性能;最后对二元及三元过渡金属氧化物的应用前景进行了展望。     

Photoluminescence Architectures for Disease Diagnosis: From Graphene to Thin‐Layer Transition Metal Dichalcogenides and Oxides

Ever since the discovery of graphene, increasing efforts have been devoted to the use of this stellar material as well as the development of other graphene‐like materials such as thin‐layer transition metal dichalcogenides and oxides (TMD/Os) for a variety of applications. Because of their large surface area and unique optical properties, these two‐dimensional materials with a size ranging from the micro‐ to the nanoscale have been employed as the substrate to construct photoluminescence architectures for disease diagnosis as well as theranostics. These architectures are built through the simple self‐assembly of labeled biomolecular probes with the substrate material, leading to signal quenching. Upon the specific interaction of the architecture with a target biomarker, the signal can be spontaneously restored in a reversible manner. Meanwhile, by co‐loading therapeutic agents and employing the inherent photo‐thermal properties of the material substrates, a combined disease imaging and therapy (theranostics) can be achieved. This review highlights the latest advances in the construction and application of graphene and TMD/O based thin‐layer material composites for single‐target and multiplexed detection of a variety of biomarkers and theranostics. These versatile material architectures, owing to their ease in preparation, low cost and flexibility in functionalization, provide promising tools for both basic biochemical research and clinical applications.