共价有机骨架储氢性能的研究进展

共价有机骨架(COFs)具有良好的热稳定性,大的表面积,高的孔隙率和极低的密度,因而显示出优异的储氢性能。重点介绍了COFs储氢性能的研究进展和目前存在的问题,提出了今后的研究重点和发展方向。     

共价有机骨架材料的CO2捕获性能研究

共价有机骨架材料(COFs)作为一类新型的纳米多孔晶体材料,由于具有表面积大、结构多样性、永久孔隙率高和热稳定性高等优点,在CO_2捕获性能方面表现出优异的应用前景。简要介绍了COFs的合成及表征方法、描述CO_2捕获性能的物理量。综述了几类COFs对CO_2捕获性能的研究进展,如含硼类、三嗪类和亚胺类COFs,并对它们的捕获性能进行了比较和总结,指出其优点和局限性。最后对未来的研究方向和发展趋势进行了展望。     

手性共价有机框架的合成及应用研究进展

共价有机框架(COFs)是由多齿有机单元通过共价键连接而成的一类新兴的多孔晶体材料。由于COFs材料具有较大的比表面积、较好的结构和化学稳定性等特征,在许多领域表现出优异的应用前景。随着手性科学的不断发展,手性COFs材料应运而生,其结构类型的设计、开发及应用备受研究者们关注。鉴于此,介绍了近年来手性COFs材料的合成策略和合成方法的研究进展,包括后修饰策略、自下而上策略和手性诱导策略,以及基于不同策略设计得到的手性COFs材料结构的类型。此外,简要介绍了手性COFs材料在手性拆分、不对称催化与色谱分析等领域的应用。     

Ti-Mn基储氢合金研究进展

综述了 Ti-Mn基储氢材料的国内外研究现状与进展。详细介绍了已研究开发的二元、三元和多元合金及其储氢性能并讨论了影响储氢性能的主要因素。     

卟啉基共价有机框架材料的电化学应用探究

共价有机框架材料(COFs)是一类新型的结晶多孔聚合物,具有孔隙高、活性位点丰富、框架结构可调等特点,广泛应用于催化、储能、气体吸附及光电子等领域。其中卟啉基COFs因具有独特的共轭π电子结构,可促进激发态电子的传输,因此在电催化领域有重要的应用。主要介绍了卟啉基COFs的合成策略及其在析氢反应(HER)、析氧反应(OER)、氧还原反应(ORR)和超级电容器的应用,并结合目前研究中存在的问题,提出了卟啉基COFs今后在电催化及储能领域的挑战和发展方向。     

共价有机骨架材料的合成及应用

共价有机骨架材料(Covalent organic frameworks,COFs)是有机单体通过可逆共价键连接形成的晶型有机多孔材料.自2005年首例COFs报道以来,大量新型COFs应运而生.COFs具有质量轻、密度低、结构规整、孔道结构可调、比表面积大、化学稳定性高的优势,在生命科学、环境保护和能源化工等方向具有巨大的应用潜力.由于功能化的COFs易实现不同物质在其内部的传输,目前研究人员已经成功将大量COFs应用于气体的吸附和分离与存储、催化剂、药物传递、有机电子器件和选择性分离薄膜等领域并取得了丰硕的研究成果.大量研究表明,COFs是高效存储CO2、H2和CH4的多孔材料,并且也可以作为催化剂载体,甚至可以直接作为催化剂用于催化各种化学反应.COFs的水分散度高且不会对细胞产生毒性,对布洛芬、5-氟尿嘧啶和槲皮素等药物表现出高效的负载和释放性能.2D COFs的π阵列型结构孔道高度规整,容易形成良好的载流子传导路径,可作为半导体元器件、超级电容器和质子交换膜等有机电子器件的理想候选材料.由于其高度有序且稳定的纳米孔道结构特性,2D COFs还可作为性能良好的纳滤薄膜,以高效分离溶剂中的染料分子.本文总结了COFs的各种特性并概述了COFs的结构设计、功能化和合成方法,综述了COFs在气体吸附与存储、催化剂、药物传递、有机电子器件和选择性分子筛薄膜领域的应用进展,并对其发展的新趋势进行了展望.     

钯在储氢材料中的作用与应用

本文介绍了钯在储氢材料中的作用、特点,以及钯在镁基储氢合金,稀土类储氢合金及碳材料中的国内外应用研究概况,并提出了储氢材料的今后发展方向。     

车载储氢研究新进展

参照燃料电池汽车对车载储氢系统单位质量储氢密度与体积储氢密度的目标要求,对目前已应用或处于研发阶段的一些储氢技术的性能指标和存在的问题进行了分析和探讨.并且介绍当前车载所采用或正在研究的主要储氢材料与技术,如高压氢气、液氢、金属氢化物储氢、吸附储氢、金属有机构架储氢等,比较各种储氢技术的优缺点,并指出其发展趋势.     

储氢材料的发展概况

主要介绍了目前研究比较多的两系列储氢材料--金属合金系列和碳系列,特别是有关金属合金系列储氢材料的储氢原理、设计和合成以及表面修饰等方面的知识,同时对碳系列储氢材料的种类、合成等也做了简要的叙述,并提出储氢材料的最终发展方向将是走向复合型的储氢材料.     

镁基储氢复合材料的研究进展

综述了镁基储氢复合材料开发和研究的最新进展，重点介绍了稀土／镁基储氢复合材料和镍／镁基储氢复合材料的主要种类、吸放氢性能和相关的制备工艺，简要分析了钛、铁、钒、锆／镁基储氢材料的研究现状和存在的问题，讨论了镁基储氢复合材料在储氢电极材料方面的应用前景。     

Nanostructured covalent organic frameworks with elevated crystallization for (electro)photocatalysis and energy storage devices

Nanostructured covalent organic frameworks (COFs) have attracted great attentions over the past few decades due to their unique physical and chemical properties. Crystallization is sought in many application fields since it allows enhancing or even promoting properties of catalysis, energy storage and photoelectric properties. However, the crystallization process of nanostructured COFs remains to be challenging. Synthetic approaches to establish nucleation and elongation growth of COFs for controlling crystallization have drawn substantial amount of attentions. Nanostructured COFs have exhibited significant advantages when applied in (electro)photocatalysis and energy storage devices as well. In this review, recent progress in precisely design strategy of fabricating various nanostructured COFs and their applications as (electro)photocatalyzer and energy storage devices are summarized. After a brief introduction of the design principles, composition and interior architecture, the morphology of nanostructured COFs including porous and mesoporous stacked-layer structure, nanosheet structure, nanorod structure, ordered stripe arrays and various nanocomposites are thoroughly described. Reactions dedicated to crystallization process for two-dimensional (2D) COFs are discussed further. Then, the applications of nanostructured COFs as (electro)photocatalysis and energy storage devices are demonstrated. Finally, the potential advantages and challenges for the synthetic technology of nanostructured COFs materials are particularly discussed. Personal insights into the challenges and opportunities on pursuing topologies as hollow structures, dense spheres, yolk–shell structures were raised to broaden the applications.

     

Recent Progress in Metal‐Free Covalent Organic Frameworks as Heterogeneous Catalysts

Covalent organic frameworks (COFs), connecting different organic units into one system through covalent bonds, are crystalline organic porous materials with 2D or 3D networks. Compared with conventional porous materials such as inorganic zeolite, active carbon, and metal‐organic frameworks, COFs are a new type of porous materials with well‐designed pore structure, high surface area, outstanding stability, and easy functionalization at the molecular level, which have attracted extensive attention in various fields, such as energy storage, gas separation, sensing, photoluminescence, proton conduction, magnetic properties, drug delivery, and heterogeneous catalysis. Herein, the recent advances in metal‐free COFs as a versatile platform for heterogeneous catalysis in a wide range of chemical reactions are presented and the synthetic strategy and promising catalytic applications of COF‐based catalysts (including photocatalysis) are summarized. According to the types of catalytic reactions, this review is divided into the following five parts for discussion: achiral organic catalysis, chiral organic conversion, photocatalytic organic reactions, photocatalytic energy conversion (including water splitting and the reduction of carbon dioxide), and photocatalytic pollutant degradation. Furthermore, the remaining challenges and prospects of COFs as heterogeneous catalysts are also presented.     

One-Dimensional Covalent Organic Framework as High-Performance Cathode Materials for Lithium-Ion Batteries

Covalent organic frameworks (COFs) have emerged as a new class of cathode materials for energy storage in recent years. However, they are limited to two-dimensional (2D) or three-dimensional (3D) framework structures. Herein, this work reports designed synthesis of a redox-active one-dimensional (1D) COF and its composites with 1D carbon nanotubes (CNTs) via in situ growth. Used as cathode materials for Li-ion batteries, the 1D COF@CNT composites with unique dendritic core–shell structure can provide abundant and easily accessible redox-active sites, which contribute to improve diffusion rate of lithium ions and the corresponding specific capacity. This synergistic structural design enables excellent electrochemical performance of the cathodes, giving rise to 95% utilization of redox-active sites, high rate capability (81% capacity retention at 10 C), and long cycling stability (86% retention after 600 cycles at 5 C). As the first example to explore the application of 1D COFs in the field of energy storage, this study demonstrates the great potential of this novel type of linear crystalline porous polymers in battery technologies.     

Electroactive Covalent Organic Frameworks: Design,Synthesis, and Applications

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers with tailorable compositions, porosities, functionalities, and intrinsic chemical stability. The incorporation of electroactive moieties in the structure transforms COFs into electroactive materials with great potential for energy-related applications. Herein, the recent advances in the design and use of electroactive COFs as capacitors, batteries, conductors, fuel cells, water-splitting, and electrocatalysis are addressed. Their remarkable performance is discussed and compared with other porous materials; hence, perspectives in the development of electroactive COFs are presented.     

Carbon‐Rich Nanomaterials: Fascinating Hydrogen and Oxygen Electrocatalysts

Hydrogen energy is commonly considered as a clean and sustainable alternative to the traditional fossil fuels. Toward universal utilization of hydrogen energy, developing high‐efficiency, low‐cost, and sustainable energy conversion technologies, especially water‐splitting electrolyzers and fuel cells, is of paramount significance. In order to enhance the energy conversion efficiency of the water‐splitting electrolyzers and fuel cells, earth‐abundant and stable electrocatalysts are essential for accelerating the sluggish kinetics of hydrogen and oxygen reactions. In the past decade, carbon‐rich nanomaterials have emerged as a promising class of hydrogen and oxygen electrocatalysts. Here, the development and electrocatalytic activity of various carbon‐rich materials, including metal‐free carbon, conjugated porous polymers, graphdiyne, covalent organic frameworks (COFs), atomic‐metal‐doped carbon, as well as metal–organic frameworks (MOFs), are demonstrated. In particular, the correlations between their porous nanostructures/electronic structures of active centers and electrocatalytic performances are emphatically discussed. Therefore, this review article guides the rational design and synthesis of high‐performance, metal‐free, and noble‐metal‐free carbon‐rich electrocatalysts and eventually advances the rapid development of water‐splitting electrolyzers and fuel cells toward practical applications.     

Structure–performance correlation guided applications of covalent organic frameworks

Pre-designed structures and tailor-made functions make covalent organic frameworks (COFs) quickly become promising reticular platforms for multidisciplinary fields. Despite the overarching success, controllable and large-scale synthesis of COFs is still a huge challenge. Moreover, the relationship between the structure and performance of COFs in various fields has not been well understood, seriously limiting their practical applications. In this review, we provide an insightful and fundamental understanding of COFs from structural perspectives, and correlate them with eventual performance in practical applications. By summarizing both the top-down and bottom-up approaches, we address how typical issues, such as the size, morphology, dispersity and stability of COFs, are resolved, which should be crucial for their function-oriented and large-scale production. Structural and physicochemical properties, such as pores, ligands, stacking, linkages, functional group, morphology, crystallinity, dimensionality and wetting, are also discussed in relation to various functions. In addition, in-depth discussions regarding the correlations between structural characteristics of COFs and their performance in catalysis, energy storage, gas/liquid adsorption and membrane separation are presented. Finally, perspectives for the future direction of this field are proposed, to provide useful guidance for the function-oriented design and scalable production of COFs to meet the practical requirements of applications.     

Effects of connecting sequences of building blocks on reticular synthesis of covalent organic frameworks

The principle of reticular chemistry has been widely used to guide the design of crystalline porous materials such as metal organic frameworks(MOFs)and covalent organic frameworks(COFs).While in the early strategies only the symmetries of the building blocks were considered for reticular synthesis of COFs,recently a few researches on COFs with hierarchical porosities indicate that connecting sequence of building blocks also plays a crucial role in determining crystalline structures of COFs.However,this important phenomenon has not been systematically investigated yet.In this article,a model system has been established to demonstrate how different connecting sequences of two C_2v-symmetric building blocks lead to the formation of four two-dimensional(2D)COFs with distinct framework structures.To verify this concept,target synthesis was conducted to produce three COFs,whose structures were confirmed by powder X-ray diffraction and pore size distribution analysis.     

Shape-Controlled Synthesis of Covalent Organic Frameworks Enabled by Polymerization-Induced Phase Separation

The shape and morphology modulations of covalent organic frameworks (COFs) are both difficult, but are of significance to tackle to realize high-performance and practical applications. Here, a two-step method is reported that separates the phase separation and crystallization processes for the shape-controlled synthesis of COFs. The insight into the polymerization-induced phase separation (PIPS) allows for the flexible shaping of COFs into column, rod, film and others, as well as for constructing hierarchically porous structure. The as-synthesized COF monoliths are crack-free, no powder detaching, and show 214 MPa of compressive modulus. The resulting good permeability and mechanical flexibility enable COF films to apply for flow-through adsorption and extraction of pollutants at high flow rates. This work successfully resolves the contradiction between PIPS and crystallization, offering a general approach for scalable production of COFs with desired shapes, sizes, and morphologies.     

Covalent Organic Framework Electrocatalysts for Clean Energy Conversion

Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, adsorption, optoelectricity, etc. owning to the unprecedented combination of large surface area, high crystallinity, tunable pore size, and unique molecular architecture. Although COFs are in their initial research stage, progress has been made in the design and synthesis of COF‐based electrocatalysis for the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO₂ reduction in energy conversion and fuel generation. Design principles are also established for some of the COF materials toward rational design and rapid screening of the best electrocatalysts for a specific application. Herein, the recent advances in the design and synthesis of COF‐based catalysts for clean energy conversion and storage are presented. Future research directions and perspectives are also being discussed for the development of efficient COF‐based electrocatalysts.     

Nanopore-Supported Metal Nanocatalysts for Efficient Hydrogen Generation from Liquid-Phase Chemical Hydrogen Storage Materials

Hydrogen has emerged as an environmentally attractive fuel and a promising energy carrier for future applications to meet the ever-increasing energy challenges. The safe and efficient storage and release of hydrogen remain a bottleneck for realizing the upcoming hydrogen economy. Hydrogen storage based on liquid-phase chemical hydrogen storage materials is one of the most promising hydrogen storage techniques, which offers considerable potential for large-scale practical applications for its excellent safety, great convenience, and high efficiency. Recently, nanopore-supported metal nanocatalysts have stood out remarkably in boosting the field of liquid-phase chemical hydrogen storage. Herein, the latest research progress in catalytic hydrogen production is summarized, from liquid-phase chemical hydrogen storage materials, such as formic acid, ammonia borane, hydrous hydrazine, and sodium borohydride, by using metal nanocatalysts confined within diverse nanoporous materials, such as metal–organic frameworks, porous carbons, zeolites, mesoporous silica, and porous organic polymers. The state-of-the-art synthetic strategies and advanced characterizations for these nanocatalysts, as well as their catalytic performances in hydrogen generation, are presented. The limitation of each hydrogen storage system and future challenges and opportunities on this subject are also discussed. References in related fields are provided, and more developments and applications to achieve hydrogen energy will be inspired.