2020 roadmap on pore materials for energy and environmental applications

Porous materials have attracted great attention in energy and environment applications, such as metal organic frameworks (MOFs), metal aerogels, carbon aerogels, porous metal oxides. These materials could be also hybridized with other materials into functional composites with superior properties. The high specific area of porous materials offer them the advantage as hosts to conduct catalytic and electrochemical reactions. On one hand, catalytic reactions include photocatalytic, photoelectrocatalytic and electrocatalytic reactions over some gases. On the other hand, they can be used as electrodes in various batteries, such as alkaline metal ion batteries and electrochemical capacitors. So far, both catalysis and batteries are extremely attractive topics. There are also many obstacles to overcome in the exploration of these porous materials. The research related to porous materials for energy and environment applications is at extremely active stage, and this has motivated us to contribute with a roadmap on ‘porous materials for energy and environment applications’.     

金属-有机框架衍生的中空碳材料及其在电化学能源存储与氧还原领域中的应用

金属-有机框架材料(metal-organic frameworks,MOFs)是一类由金属离子或金属团簇与有机配体通过配位键连接形成的具有周期性网络结构的多孔配位聚合物。这类材料通常具有孔道规整、比表面积大、孔隙率高、结构可设计及孔壁易修饰等特点,诸多的优点使得MOFs的研究从配位化学跨越到多个学科领域,成为当前多学科交叉前沿热点之一。近来的研究发现,以MOFs为前驱体碳化后制得的碳材料可保留MOFs的大比表面积和多孔结构,同时可以实现均匀的杂原子(如N、P、S、B等)掺杂,而且通过选择合适的MOFs前驱体可调控产物的组成和形貌尺寸,这些显著的结构特征使其具备了成为高性能功能性材料的潜力。最近,以MOFs为模板或前驱体制备的中空碳材料引起了人们的广泛关注,这主要是因为中空结构可有效缓解材料在电化学过程中产生的体积变化及受到的冲击,而且中空结构可暴露出更多的活性位点,具有快速的传质过程,使得材料发挥出最优性能,故而此类材料可被用在二次电池、电容器、电催化等多种电化学器件和多个领域中。基于此,本文综述了MOFs衍生的中空碳材料在储能器件及电催化领域的研究进展,主要包括锂离子电池、锂硫/硒电池、钠离子电池、超级电容器、电催化氧还原等领域,并对这类材料当前面临的挑战及未来的发展趋势进行了阐述。     

2020 Roadmap on Carbon Materials for Energy Storage and Conversion

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on ‘Carbon Materials in Energy Storage and Conversion’.     

离子液体功能化金属/共价-有机框架材料在催化反应中应用

离子液体（ILs）功能化的金属有机框架（MOFs）和共价有机框架（COFs）材料兼具离子液体和MOFs/COFs的优点，是一种极具潜力的复合催化材料。MOFs和COFs材料固定的孔结构及较大的比表面积为负载高分散催化中心提供了天然的物理空间；多孔结构促使催化剂与反应物充分接触；丰富的孔道有利于运输催化反应底物和产物，进而实现催化反应的高效进行。特别是离子液体片段的引入，可以作为催化活性中心的配体（稳定剂）或分散剂，同时能够有效改善MOFs和COFs材料孔道和活性中心周围的微环境。此外，还可以充分利用离子液体片段在适当的反应条件下转化为氮杂环卡宾配体的特点，在MOFs和COFs材料中引入氮杂环卡宾有机金属配合物。因此，我们对近几年来离子液体功能化的MOFs或COFs催化体系在CO2环加成、CO2还原、C-C偶联、羰基化以及其它有机转化反应中的研究应用进行简要综述。并对复合材料在催化领域的发展进行总结和展望。     

核壳结构金属-有机骨架及其衍生物在锂离子电池负极材料中的应用

金属–有机框架(MOFs)材料具有比表面积较大、孔径可调、制备容易、结构与功能多样性等优势,被广泛应用于电化学能源转化与储存领域。其中独特的核壳结构材料由于表面修饰的作用往往更能表现出核内与壳层的协同作用。本文介绍了具有核壳结构MOFs作为锂离子电池负极材料的发展现状,并重点综述其衍生物(多孔碳材料、金属氧化物、金属硫/硒化物以及金属/金属氧化物)的制备方法以及在锂离子电池负极中的应用。MOFs通过高温煅烧或改变化学反应条件的方法,可制备出结构可调的传统无机电极材料并表现出更优异的电化学性能。最后总结了核壳结构MOFs材料作为锂电负极材料存在的问题和挑战,并提出可能的解决途径和未来的应用前景。     

高效氧催化反应中的金属有机骨架材料（英文）

氧电催化反应包括氧气还原反应(ORR)和氧气析出反应(OER).作为核心电极反应,这两个反应对诸多能源存储与转换技术(比如燃料电池、金属空气电池以及全水分解制氢等)的能量效率起决定性作用.然而,ORR和OER涉及多个反应步骤、多个电子转移过程以及多相界面传质过程.这些复杂的过程较大程度上限制了ORR和OER的反应速率.从理论和实践两个方面来看,ORR和OER都需要高效电催化剂的参与来促进其反应速率,从而能够最终提高上述能源存储与转换技术的能量转换或利用效率.目前,以Pt,Pd,Ir,Ru为代表的贵金属基电催化剂具有十分突出的电催化性能.但是,过高的成本和过低的储量始终制约着贵金属基电催化剂在催化ORR和OER反应方面,乃至在能源存储与转换技术领域的规模化应用.因而,开发高效非贵金属基氧电催化剂成为近年来能源存储与转换领域的研究重点之一.在众多已经报道的非贵金属基氧电催化剂中,金属有机骨架材料(MOFs)备受瞩目.MOFs是一类由有机配体和金属节点通过配位键自组装而成的晶态多孔材料.它们具备超高比表面积、超高孔隙率以及规则性纳米孔道.相比较其他传统的多孔材料(比如活性炭、分子筛、介孔炭、介孔氧化硅等),MOFs最主要的优势在于它们的结构和功能可以依据需求通过选择合适的有机配体和金属节点进行便利地设计,或通过后处理进行必要的改性和调节.基于独特的多孔特性以及结构与功能的可设计、可调节性,MOFs在气体分离与存储、异相催化、化学传感、药物输送、环境保护以及能源存储与转化等领域都具有潜在的应用价值.因而,近年来,MOFs备受基础研究领域和工业界的青睐.针对MOFs开展的基础研究和应用开发逐渐成为诸多领域的研究焦点.也正由于MOFs具有的上述优异特性,尤其是结构与功能的可设计、可调节性,使得设计制备基于单纯MOFs以及MOFs衍生材料成为开发高效非贵金属基氧电催化剂的新途径.本综述首先论述了基于单纯MOFs的氧电催化剂(包括纯MOFs、活性物种修饰的MOFs以及与导电材料构成的复合MOFs)的合成以及它们在ORR或OER催化反应中应用的研究进展.在第二部分论述中,本综述主要针对MOFs衍生的各类氧电催化剂(包括无机微米-纳米结构/多孔碳复合材料、纯多孔碳材料、纯无机微米-纳米结构材料以及单原子型电催化材料)的研究进展进行了简要介绍和讨论.最后,本综述对MOFs基氧电催化剂目前存在的挑战进行了简要分析;同时,也对这类氧电催化剂的通用设计准则以及未来发展方向进行了展望.尽管存在诸多挑战,MOFs始终被认为是极好的"平台"材料.充分利用它们将有利于开发高效且实用的非贵金属基氧电催化剂.     

Biomolecule-assisted synthesis and electrochemical hydrogen storage of porous spongelike Ni3S2 nanostructures grown directly on nickel foils

Nanothread-based porous spongelike Ni3S2 nanostructures were synthesized directly on Ni foil by using a simple biomolecule-assisted method. By varying the experimental parameters, other novel Ni3S2 nanostructures could also be fabricated on the nickel substrate. The electrochemical hydrogen-storage behavior of these novel porous Ni3S2 nanostructures was investigated as an example of the potential properties of such porous materials. The thread-based porous spongelike Ni3S2 could electrochemically charge and discharge with the high capacity of 380 mAh g(-1) (corresponding to 1.4 wt % hydrogen in single-walled nanotubes (SWNT)). A novel two-charging-plateaux phenomenon was observed in the synthesized porous spongelike Ni3S2 nanostructures, suggesting two independent steps in the charging process. We have demonstrated that the morphology of the synthesized Ni3S2 nanostructures had a noticeable influence on their electrochemical hydrogen-storage capacity. This is probably due to the size and density of the pores as well as the microcosmic morphology of different nickel sulfide nanostructures. These novel porous Ni3S2 nanostructures should find wide applications in hydrogen storage, high-energy batteries, luminescence, and catalytic fields. This facile, environmentally benign, and solution-phase biomolecule-assisted method can be potentially extended to the preparation of other metal sulfide nanostructures on metal substrates, such as Cu, Fe, Sn, and Pb foils.     

Organic Positive Materials for Magnesium Batteries: A Review

Magnesium batteries, like lithium-ion batteries, with higher abundance and similar efficiency, have drawn great interest for large-scale applications such as electric vehicles, grid energy storage and many more. On the other hand, the use of organic electrode materials allows high energy-performance, metal-free, environmentally friendly, versatile, lightweight, and economically efficient magnesium storage devices. In particular, the structural diversity and the simple activity of organic molecules make redox properties, and hence battery efficiency, easy to monitor. While organic magnesium batteries still in their infancy, this field becomes more and more promising because significant results were reported. To summarize the achievements in studies on organic cathodes for magnesium systems, their synthesis is discussed, combined with electrode design to provide the basis for controlling the electrochemical properties. Moreover, the techniques to synthesize organic materials with high-yield are mentioned. Finally, potential problems and prospects are explored to further improve organic cathodes.     

2020 roadmap on two-dimensional materials for energy storage and conversion

In this roadmap, two-dimensional materials including graphene, black phosporus, MXenes, covalent organic frameworks, oxides, chalcogenides, and others, are highlighted in energy storage and conversion.     

Progress and Perspectives on Covalent-Organic Frameworks (COFs) and Composites for Various Energy Applications

Covalent-organic frameworks (COFs), being a new member of the crystalline porous materials family, have emerged as important materials for energy storage/conversion/generation devices. They possess high surface areas, ordered micro/mesopores, designable structures and an ability to precisely control electro-active groups in their pores, which broaden their application window. Thanks to their low weight density, long range crystallinity, reticular nature and tunable synthesis approach towards two and three dimensional (2D and 3D) networks, they have been found suitable for a range of challenging electrochemical applications. Our review focuses on the progress made on the design, synthesis and structure of COFs and their composites for various energy applications, such as metal-ion batteries, supercapacitors, water-splitting and solar cells. Additionally, attempts have been made to correlate the structural and mechanistic characteristics of COFs with their applications.     

2020 roadmap on two-dimensional materials for energy storage and conversion

Energy storage and conversion have attained significant interest owing to its important applications that reduce CO₂ emission through employing green energy. Some promising technologies are included metal-air batteries, metal-sulfur batteries, metal-ion batteries, electrochemical capacitors, etc. Here, metal elements are involved with lithium, sodium, and magnesium. For these devices, electrode materials are of importance to obtain high performance. Two-dimensional (2D) materials are a large kind of layered structured materials with promising future as energy storage materials, which include graphene, black phosporus, MXenes, covalent organic frameworks (COFs), 2D oxides, 2D chalcogenides, and others. Great progress has been achieved to go ahead for 2D materials in energy storage and conversion. More researchers will join in this research field. Under the background, it has motivated us to contribute with a roadmap on ‘two-dimensional materials for energy storage and conversion.     

Recent Advances in Porous Carbon Materials for Electrochemical Energy Storage

Climate change and the energy crisis have promoted the rapid development of electrochemical energy‐storage devices. Owing to many intriguing physicochemical properties, such as excellent chemical stability, high electronic conductivity, and a large specific surface area, porous carbon materials have always been considering as a promising candidate for electrochemical energy storage. To date, a wide variety of porous carbon materials based upon molecular design, pore control, and compositional tailoring have been proposed for energy‐storage applications. This focus review summarizes recent advances in the synthesis of various porous carbon materials from the view of energy storage, particularly in the past three years. Their applications in representative electrochemical energy‐storage devices, such as lithium‐ion batteries, supercapacitors, and lithium‐ion hybrid capacitors, are discussed in this review, with a look forward to offer some inspiration and guidelines for the exploitation of advanced carbon‐based energy‐storage materials.     

石墨烯基催化剂的设计合成与电催化应用

为了解决能源匮乏和环境污染的问题,研究人员正致力于寻找清洁可持续的新能源。 其中,氧气还原、氧气析出、析氢反应等是紧密联系新型清洁能源获取和存贮的重要电化学反应。 为了提高其能量转化效率,电催化剂(如碳载铂Pt/C)被广泛地用于降低其反应活化能、提高能量转化效率。 近年来,石墨烯作为一种具有高比表面积和优异导电性的二维碳材料受到了广泛关注。 通过表面杂原子掺杂、缺陷调控和引入催化活性组分等方式,获得了催化性能与贵金属催化剂相媲美,且低价格和高稳定性的非贵金属石墨烯基催化材料。 针对氧气还原、氧气析出和析氢反应在燃料电池、金属-空气电池和电催化水分解中的应用,本文概括综述了通过表/界面结构性质调控提高石墨烯电催化性能和稳定性,获得具有双功能或复合催化性能的石墨烯基催化剂的最新研究进展。 最后总结和展望了亟待解决的问题及未来的发展趋势。     

Hierarchically Porous Organic Materials Derived From Copolymers: Preparation and Electrochemical Applications

Abstract

Compared to conventional porous materials with a uniform pore size distribution, hierarchical ones containing interconnected macro-, meso-, and micropores have greatly enhanced material performance due to the increased specific surface area and mass transfer. Copolymer is a good candidate used for construction of such hierarchically porous structures, resulting from its tunable segment composition, unique phase separation, and self-assembly, etc. Hierarchically porous materials derived from copolymers can be served as a versatile support for many reactive molecules. Furthermore, hierarchically porous carbon materials (HPCMs) can also be prepared by carbonization of copolymers, one segment of which is converted to carbon while the other segment is responsible for the pore formation after its removal by pyrolysis. The obtained hierarchically porous copolymers or carbon materials have promising electrochemical applications especially in energy conversion and storage. In the present review, recent advances in preparation of hierarchically porous materials (HPMs) derived from copolymers are reviewed, and their electrochemical applications in supercapacitors, lithium-ion batteries, fuel cells, electrochemical biosensors, and electrocatalysis are also introduced. The rational design and control for the hierarchically porous microstructures are described deeply from the molecular level. Also, the relationship between the micro-structure and the electrochemical performance is revealed. This review can provide us a better understanding of both theory and experiment for the preparation of hierarchically porous organic materials and their electrochemical applications.     

基于有机物电极的电化学能量存储与转化

由于高安全的特性,水系二次电池被认为是未来大型储能的有效解决方案之一. 然而,现有水系电池主要以含金属元素的无机化合物为电极活性材料,其在大型储能中的实际应用仍受到循环寿命、环境问题、原料成本或金属元素丰度的限制. 相较于无机电极材料,部分有机电极材料具有原料丰富、结构丰富、可持续及环境友好等优点. 此外,有机物材料分子内空间大,能够存储不同价态电荷,因此近年来被广泛关注. 本文综述了课题组近期在有机物电极方面的研究进展,内容聚焦含羰基有机物通过C=O/C-O-的可逆转化存储单价金属阳离子(Li⁺, Na⁺)、双价金属阳离子(Zn²⁺)、质子(H⁺)所涉及的电化学过程,及其在水系锂、钠离子电池、水系锌离子电池、质子电池以及分步电解水中的应用.     

Engineering Metal–Organic Framework Catalysts for C−C and C−X Coupling Reactions: Advances in Reticular Approaches from 2014–2018

Metal–organic frameworks (MOFs) are a class of crystalline porous materials that have been actively used for several industrial and synthetic applications. MOFs are spatially and geometrically extrapolated coordination polymers with intriguing properties such as tunable porosity and dimensionality. In terms of their catalytic efficiency, MOFs combine the easy recoverability of heterogeneous catalysts with the increased selectivity of biological catalysts. It is therefore not surprising that a lot of work on optimizing MOF catalysts for organic transformations has been carried out over the past decade. In this review, recent developments in MOF catalysis are summarized, with special attention being paid to C−C, C−N, and C−O coupling reactions. The influence of pore size, pore environment, and load on catalytic activity is described. Post-synthetic stabilization techniques and host–guest interactions in caged MOF scaffolds are detailed. Mechanistic aspects pertaining to the use of MOFs in asymmetric heterogeneous catalysis are highlighted and categorized.     

Silica‐Protection‐Assisted Encapsulation of Cu2O Nanocubes into a Metal–Organic Framework (ZIF‐8) To Provide a Composite Catalyst

The integration of metal/metal oxide nanoparticles (NPs) into metal–organic frameworks (MOFs) to form composite materials has attracted great interest due to the broad range of applications. However, to date, it has not been possible to encapsulate metastable NPs with high catalytic activity into MOFs, due to their instability during the preparation process. For the first time, we have successfully developed a template protection–sacrifice (TPS) method to encapsulate metastable NPs such as Cu₂O into MOFs. SiO₂ was used as both a protective shell for Cu₂O nanocubes and a sacrificial template for forming a yolk–shell structure. The obtained Cu₂O@ZIF‐8 composite exhibits excellent cycle stability in the catalytic hydrogenation of 4‐nitrophenol with high activity. This is the first report of a Cu₂O@MOF‐type composite material. The TPS method provides an efficient strategy for encapsulating unstable active metal/metal oxide NPs into MOFs or maybe other porous materials.     

Metal–Organic Framework‐Templated Porous Carbon for Highly Efficient Catalysis: The Critical Role of Pyrrolic Nitrogen Species

Metal‐free catalysts are of great importance and alternative candidates to conventional metal‐based catalysts for many reactions. Herein, several types of metal–organic frameworks have been exploited as templates/precursors to afford porous carbon materials with various nitrogen dopant forms and contents, degrees of graphitization, porosities, and surface areas. Amongst these materials, the PCN‐224‐templated porous carbon material optimized by pyrolysis at 700 °C (denoted as PCN‐224‐700) is composed of amorphous carbon coated with well‐defined graphene layers, offering a high surface area, hierarchical pores, and high nitrogen content (mainly, pyrrolic nitrogen species). Remarkably, as a metal‐free catalyst, PCN‐224‐700 exhibits a low activation energy and superior activity to most metallic catalysts in the catalytic reduction of 4‐nitrophenol to 4‐aminophenol. Theoretical investigations suggest that the content and type of the nitrogen dopant play crucial roles in determining the catalytic performance and that the pyrrolic nitrogen species makes the dominant contribution to this activity, which explains the excellent efficiency of the PCN‐224‐700 catalyst well.     

Recent Advances in Covalent Organic Frameworks for Catalysis

Covalent organic frameworks (COFs) as an emerging type of crystalline porous materials, have obtained considerable attention recently. They have exhibited diverse structure and attractive performance in various catalytic reactions. It is highly expected to have a systematic and comprehensive review summing up COFs‐derived catalysts in homogeneous and heterogeneous catalysis, which is favorable to the judicious design of an efficient catalyst for targeted reaction. Herein, we focus on summarizing recent and significant developments in COFs materials, with an emphasis on both the synthetic strategies and targeted functionalization, and categorize it in accordance with the different types of catalytic reactions. Their potential catalysis applications are reviewed thoroughly. Moreover, a personal view about the future development of COFs catalysts with respect to the large‐scale production is also discussed.     

Unlocking Reversible Silicon Redox for High-Performing Chlorine Batteries

Chlorine (Cl)-based batteries such as Li/Cl₂ batteries are recognized as promising candidates for energy storage with low cost and high performance. However, the current use of Li metal anodes in Cl-based batteries has raised serious concerns regarding safety, cost, and production complexity. More importantly, the well-documented parasitic reactions between Li metal and Cl-based electrolytes require a large excess of Li metal, which inevitably sacrifices the electrochemical performance of the full cell. Therefore, it is crucial but challenging to establish new anode chemistry, particularly with electrochemical reversibility, for Cl-based batteries. Here we show, for the first time, reversible Si redox in Cl-based batteries through efficient electrolyte dilution and anode/electrolyte interface passivation using 1,2-dichloroethane and cyclized polyacrylonitrile as key mediators. Our Si anode chemistry enables significantly increased cycling stability and shelf lives compared with conventional Li metal anodes. It also avoids the use of a large excess of anode materials, thus enabling the first rechargeable Cl₂ full battery with remarkable energy and power densities of 809 Wh kg⁻¹ and 4,277 W kg⁻¹, respectively. The Si anode chemistry affords fast kinetics with remarkable rate capability and low-temperature electrochemical performance, indicating its great potential in practical applications.