MOFs光催化材料的设计和调控（英文）

环境污染和能源短缺是制约当今社会发展的重大问题.光催化技术可直接利用太阳能驱动一系列重要的化学反应,具有能耗低、反应条件温和、无二次污染等优点,是解决这一问题的有效途径.实现这个过程的关键在于寻找设计高效的光催化剂.目前,光催化材料主要由无机半导体组成,其结构的改造和修饰难度很大,难以根据实际需要来控制其大小、形状以及物理化学特性.而有机化合物具有优良的分子剪裁与修饰的功能,但它们却在坚固性与稳定性等方面具有明显的缺点.因此如果能发展既具有无机化合物的稳定性又具有有机化合物的可剪裁与修饰性的新型光催化材料,无疑将促进光催化的发展和应用.金属-有机骨架材料(Metal-Organic Frameworks,MOFs)正是这样一类结合了无机物的稳定性和有机物的可修饰性的杂化材料.MOFs是一类以金属阳离子为节点、有机配体为连接体的多孔配位聚合物的总称.这类材料不仅拥有超高的比表面积、丰富的拓扑结构,而且其结构兼具可剪裁性、可设计性、易调变等特点,在气体吸附储存、分离、传感等领域都有广泛的应用.在催化领域MOFs也显示出巨大的应用前景:(1)比表面积大,有利于对反应底物的吸附,促进催化反应的进行;(2)组成多样,结构具可剪裁性、可设计性、易调变等特点,通过对其金属单元或者配体进行改变修饰,可以实现对MOFs结构和性能的调变;(3)MOFs中金属-氧单元之间由有机配体隔开,相当于分立的半导体量子点,在反应中不易发生团聚.并且各个分立的金属-氧单元之间可能存在协同效应,有利于保持催化剂的稳定性和产生高的催化活性.因此,MOFs材料是一类非常有潜力的异相催化剂.光催化是一类典型的多相催化技术,与传统半导体光催化材料相比,MOFs由于具有可在分子水平进行灵活调控的优点,在光催化领域的应用更有优势.此外,MOFs结构上的确定性为研究催化剂的界面电荷迁移和光催化机理提供了便利条件,通过对其构-效关系的研究和光催化反应机理的探索反过来有助于我们从微观尺度上进一步认识光催化的本质.MOFs材料在光催化领域已经有了初步的研究.越来越多的MOFs材料被成功应用于光催化降解染料、选择性转化有机物、光解水制氢和CO2还原等反应.典型的有MOF-5、Ui O-66和MIL-125系列等.近年来,已有少量的文献综述了MOFs这类材料在光催化领域的研究.这些文献主要围绕MOFs在光催化过程中所起到的作用,比如作为催化剂、助催化剂或载体来展开;或者是从MOFs的光催化应用领域,比如污染物降解、产氢、二氧化碳还原、有机物转化来分类展开.本文围绕如何设计合成高效的MOFs光催化剂,综述了近年来国内外关于提高MOFs的光催化性能而开展的相关研究工作,包括理论研究MOFs的能级结构及化学性质、在MOFs配体上修饰官能团调变其能带结构、染料或者金属化合物光敏化MOFs提高其光吸收性能、负载金属/碳材料及半导体复合提高光生载流子的分离效率等.最后,本文对MOFs光催化剂的未来发展趋势进行了展望,强调开发新型的MOFs光催化剂,并加强对MOFs光催化机制的研究,有助于指导现有MOFs催化剂的改良和设计新型光催化剂.     

金属有机框架(MOFs)基光催化剂的设计及其在太阳能燃料生产和污染物降解领域的研究进展

金属有机骨架(MOFs)具有较高的比表面积,丰富的金属/有机物种,较大的孔体积以及结构和成分可调节的特性,因此在太阳能燃料生产和污染物的光降解领域具有广泛的应用.根据其结构特点,研究者们主要从有机配体和孔道结构两方面对MOFs进行调控:(1)对有机配体进行修饰,如将杂原子、羟基、卤素原子、金属离子、生物大分子等引入MOFs结构;(2)将无机纳米粒子引入MOFs孔道内,如将贵金属、金属氧化物、多金属氧酸盐等纳米粒子封装在MOFs的孔道内.这些策略可有效增强MOFs的导电性、稳定性等,并进一步提高MOFs基催化剂的光催化性能.本文首先概述了四种经典MOFs类型,即UiO,ZIF,MIL和PCN系列的结构特点和催化性能.其次,总结了在设计MOFs基光催化材料过程中,根据不同类型MOFs特点着重考虑的五方面因素,即稳定性、能带结构、吸附作用、选择性和电导性.再次,讨论了提高MOFs基光催化剂活性的策略,如助催化剂修饰、构建异质结、配体或金属中心修饰和缺陷工程.最后,总结了MOFs基光催化材料在催化还原CO₂、分解水制氢和降解有机污染物反应中的应用进展及影响其催化性能的主要因素.尽管MOFs基光催化材料研究已经取得了令人瞩目的进展,但对MOFs基光催化剂进行可控设计制备仍然存在挑战.如何实现纳米MOFs基光催化材料的制备与规模化生产、可调缺陷MOFs基光催化材料的精准设计、开发高稳定性的MOFs基光催化材料等仍需进一步探索.因此,未来需要从MOFs的纳米化合成、复合材料界面结构的精准调控、催化活性机制与稳定性关系等方面对MOFs基光催化材料进行深入的研究.     

金属有机框架材料在光催化中的应用

金属-有机框架材料(metal-organic frameworks,MOFs)是一类基于金属离子与有机配体组装而成的配位多孔材料,具有高比表面积、多活性位点、结构可剪裁、易功能化等特征.相当一部分MOFs能够表现出类半导体的行为,其有序结构不利于光生电子-空穴复合中心的产生,同时其多孔特性更是便于光生载流子的快速/高效利用.因此,近年来MOFs材料在光催化领域受到越来越广泛的关注与研究.本文从光催化反应类型出发,包括光催化染料降解、光催化有机物转化、光催化裂解水产氢、光催化水氧化、光催化二氧化碳还原反应等,总结了近年来MOFs及其复合催化剂设计合成及在光催化领域的应用研究进展,同时简要介绍了部分MOF衍生材料在光催化领域的应用,并对MOFs材料在光催化领域的应用前景进行了展望.     

金属有机框架(MOFs)基光催化剂的设计及其在太阳能燃料生产和污染物降解领域的研究进展（英文）

金属有机骨架(MOFs)具有较高的比表面积,丰富的金属/有机物种,较大的孔体积以及结构和成分可调节的特性,因此在太阳能燃料生产和污染物的光降解领域具有广泛的应用.根据其结构特点,研究者们主要从有机配体和孔道结构两方面对MOFs进行调控:(1)对有机配体进行修饰,如将杂原子、羟基、卤素原子、金属离子、生物大分子等引入MOFs结构;(2)将无机纳米粒子引入MOFs孔道内,如将贵金属、金属氧化物、多金属氧酸盐等纳米粒子封装在MOFs的孔道内.这些策略可有效增强MOFs的导电性、稳定性等,并进一步提高MOFs基催化剂的光催化性能.本文首先概述了四种经典MOFs类型,即UiO, ZIF, MIL和PCN系列的结构特点和催化性能.其次,总结了在设计MOFs基光催化材料过程中,根据不同类型MOFs特点着重考虑的五方面因素,即稳定性、能带结构、吸附作用、选择性和电导性.再次,讨论了提高MOFs基光催化剂活性的策略,如助催化剂修饰、构建异质结、配体或金属中心修饰和缺陷工程.最后,总结了MOFs基光催化材料在催化还原CO_2、分解水制氢和降解有机污染物反应中的应用进展及影响其催化性能的主要因素.尽管MOFs基光催化材料研究已经取得了令人瞩目的进展,但对MOFs基光催化剂进行可控设计制备仍然存在挑战.如何实现纳米MOFs基光催化材料的制备与规模化生产、可调缺陷MOFs基光催化材料的精准设计、开发高稳定性的MOFs基光催化材料等仍需进一步探索.因此,未来需要从MOFs的纳米化合成、复合材料界面结构的精准调控、催化活性机制与稳定性关系等方面对MOFs基光催化材料进行深入的研究.     

金属-有机框架衍生的多功能光催化剂

在光催化过程中,光催化剂被太阳能激发产生光生电子和空穴,来实现环境净化或能量转换,是应对全球变暖和能源短缺的有效途径之一.然而,光催化技术面临的主要瓶颈问题是光生载流子的低分离效率和高反应能垒.而催化剂本身的特性对这一点起到了决定性的作用.因此,催化剂的合理设计和改性是提高光催化效率的关键.金属有机框架(MOFs)是一类由金属节点和有机配体组成的新型结晶多孔材料.基于结构多样性、超高比表面积、形状和尺寸可调的纳米孔或纳米通道等优异的特性,MOFs基材料在光催化领域引起了广泛关注.然而,MOFs的主要问题之一是低导电性和稳定性,这限制了其更广泛应用.正是由于MOFs的不稳定性,其可以作为牺牲模板制备纳米材料.由MOFs衍生的纳米材料继承了MOFs的优异特性,同时避免了MOFs较差的导电性和稳定性的问题.并且可以通过选择特定的金属节点和有机配体对MOFs衍生的纳米材料进行调控,从而实现光催化剂的多功能性.因此,MOFs衍生物在光催化领域展现出更广阔的应用前景.而且MOFs衍生物不仅可以作为半导体光催化剂,还可以作为光催化析氢、CO₂还原、污染物降解等反应的助催化剂.本文重点介绍MOFs衍生物在光催化领域的多功能应用.从MOFs衍生物的制备、修饰和应用等方面对近年来的研究进行了分析和总结.最后,对MOFs衍生物应用于光催化领域的挑战进行了分析,并对未来发展和机遇进行了展望,以期为该领域的进一步研究提供更多参考,并带来新的启示.     

羧基配体金属有机骨架材料作为催化剂的研究进展

<正>金属有机骨架材料(MOFs)是由无机金属中心与多齿有机配体通过配位键形成的立体网络结构多孔晶体材料[1].MOFs具有多孔性、大比表面积、结构规整、有机配体的可修饰性、金属离子的可选择性等特点,在气体吸附、气体分离、磁性材料、光学材料和催化剂等领域得到广泛的应用[2-6].尤其是在催化方面,MOFs结合了金属有机配合物和分子筛的优点,可以直接用作催化剂,也可作为催化剂载体使用.     

金属-有机骨架材料的改性方法及其光催化制氢应用

能源问题一直是关乎人类命运的重要问题,光催化制氢被认为是有望解决这一问题的潜在途径之一.金属有机框架(MOFs)由于其多孔、高比表面积、带隙可调等特性,在光催化制氢方面得到了广泛关注.我们综述了近些年来在金属-有机骨架材料光催化制氢领域的各种改性方法 ,包括修饰有机连接配体、修饰金属中心、金属纳米粒子沉积、染料敏化与其他功能材料结合等.概括了改性后的MOFs光催化制氢性能,指出了MOFs基光催化制氢存在的问题和可能的解决思路,并展望了MOFs基光催化制氢剂的绿色未来.     

CuO修饰改性沸石咪唑框架催化剂的构建及其光催化产氢性能(英文)

新型金属有机骨架(MOFs)材料是一类比较新颖的可用作光催化剂的潜在材料.它是由金属离子或金属簇单元与有机配体通过配位作用自组装形成的一类具有周期性多维网络结构的多孔晶态材料.MOFs结构具有高度的有序性、一定程度上的可设计性和可剪裁性,其高度发达的孔结构使得它具有超高的比表面积.MOFs结构中的金属簇被认为可以扮演半导体量子点的角色,同时其有机配体基于"天线效应",在光激发条件下用来活化这些金属簇,从而使得MOFs成为可能的光催化剂.ZIF-9由角共享四面体CoN4单元组成,其中Co2+阳离子和苯并咪唑阴离子之间的配位键是N供体配体,因而具有良好的热稳定性和较高的碳氮含量.本文在一定浓度的甲醇溶液中通过光沉积法将CuO附着于ZIF-9表面上,用于光催化活性测试,并与g-C_3N_4/CuO催化剂进行了比较.结果表明,ZIF-9/CuO催化剂活性是g-C_3N_4/CuO催化剂的19.4倍.这是由于比表面积的不同,导致所吸附的染料与暴露的活性位点的不同.通过SEM,TEM,EDS,XRD,XPS,UV-Vis和稳态瞬态荧光等手段系统研究了催化剂反应动力学行为及内在机理.稳态荧光结果表明,染料的荧光发射峰和ZIF-9的吸收峰之间没有明显的重叠,染料的激发电子可以在该反应系统中从染料分子转移到ZIF-9上.除了一部分电子直接传输到达ZIF-9表面,更多的电子将最终通过CuO到达催化剂表面,最后与反应溶液中的H~+结合生成H_2,EY-ZIF-9/CuO(40%)的荧光衰减可以用双指数荧光衰减动力学即动态淬火机理.表明CuO的引入可以增强染料EY分子的聚集,从而增加该催化剂活性.     

金属有机骨架材料在催化中的应用

金属有机骨架(MOFs)材料是一种相对新型的多孔材料,由于其结构的多样性、可设计性、可剪裁性以及超高的比表面积,近年来吸引了广泛的研究兴趣,并在很多领域展现了潜在的应用前景.特别是在催化方面的应用更受到了强烈的关注.本文的前两部分主要以催化活性位点的来源进行分类,包括配位不饱和金属中心、功能性有机配体、化学修饰接入功能位点以及嵌入在MOFs孔内的金属配合物或金属纳米颗粒等,总结了近几年来MOFs及其复合材料在多相催化方向取得的一些进展.同时在后面两部分也简要地介绍了MOFs在光催化及以MOFs为模板构筑的多孔纳米材料在催化(特别是电催化)方面的一些应用.最后,对MOFs在催化方面的应用前景做了展望.     

金属有机框架色谱固定相的研究进展

金属有机框架(MOFs)是由金属离子或金属簇与有机配体通过配位作用自组装形成的一类新型多孔材料. MOFs具有独特的拓扑结构、丰富的孔隙结构、可调的孔道尺寸、巨大的比表面积以及灵活的表面修饰等特征,是色谱分离领域颇受关注的一类新型固定相. 综述了近几年MOFs材料作为固定相在气相色谱、液相色谱及手性拆分等领域应用的研究进展,展现MOFs材料在色谱分离领域的优异性能和应用潜力,并对MOFs材料在色谱固定相领域今后的发展进行了展望.     

Electrically Conductive Porous Metal–Organic Frameworks

Owing to their outstanding structural, chemical, and functional diversity, metal–organic frameworks (MOFs) have attracted considerable attention over the last two decades in a variety of energy‐related applications. Notably missing among these, until recently, were applications that required good charge transport coexisting with porosity and high surface area. Although most MOFs are electrical insulators, several materials in this class have recently demonstrated excellent electrical conductivity and high charge mobility. Herein we review the synthetic and electronic design strategies that have been employed thus far for producing frameworks with permanent porosity and long‐range charge transport properties. In addition, key experiments that have been employed to demonstrate electrical transport, as well as selected applications for this subclass of MOFs, will be discussed.     

金属-有机框架材料在光电催化水分解领域的研究进展

光催化分解水是将太阳能转化为化学能的有效手段之一. 相比于粉末光催化, 采用H型电解池的光 电催化方法具有材料选择范围大、 载流子迁移和分离效率高、 电极易于回收等优点. 近年来, 金属有机框架 材料(MOFs)在光电催化水分解领域得到越来越多的应用. 相比于传统无机催化剂, MOFs光电极具有比表面积大、 结构易于调控等独特优势. 本文按照MOFs的应用形式分为纯MOFs、 MOFs与其它催化剂的复合结构和MOFs衍生物3类, 总结了近年来MOFs在光电催化水分解领域的研究现状和进展, 介绍了光催化/电催化领域的部分典型研究成果, 最后讨论了MOFs在光电催化水分解领域研究的重点和热点, 并对其未来发展做出了展望.     

Metal–Organic Framework (MOF) Compounds: Photocatalysts for Redox Reactions and Solar Fuel Production

Metal–organic frameworks (MOFs) are crystalline porous materials formed from bi‐ or multipodal organic linkers and transition‐metal nodes. Some MOFs have high structural stability, combined with large flexibility in design and post‐synthetic modification. MOFs can be photoresponsive through light absorption by the organic linker or the metal oxide nodes. Photoexcitation of the light absorbing units in MOFs often generates a ligand‐to‐metal charge‐separation state that can result in photocatalytic activity. In this Review we discuss the advantages and uniqueness that MOFs offer in photocatalysis. We present the best practices to determine photocatalytic activity in MOFs and for the deposition of co‐catalysts. In particular we give examples showing the photocatalytic activity of MOFs in H₂ evolution, CO₂ reduction, photooxygenation, and photoreduction.     

卟啉框架材料在光催化领域的应用

卟啉分子对可见光具有较强吸收能力,被广泛应用于光催化和光敏化材料的设计开发。 基于卟啉单元设计构筑框架结构材料,可以借助框架结构的大比表面积和可调控孔结构,实现对卟啉单元光物理化学性质的修饰和调控,达到提高材料光催化量子产率和光催化选择性的目的。 本文综述了卟啉基金属有机框架材料(MOFs)、卟啉基共价有机框架材料(COFs)、以及卟啉基多孔共价有机聚合物(COPs)在光催化领域的研究进展,通过归纳需要解决的关键问题,对卟啉框架材料的未来发展进行了展望。     

Recent Approaches to Design Electrocatalysts Based on Metal–Organic Frameworks and Their Derivatives

Rational design and synthesis of efficient electrocatalysts are important constituents in addressing the currently growing provision issues. Typical reactions, which are important to catalyze in this respect, include CO₂ reduction, the hydrogen and oxygen evolution reactions as well as the oxygen reduction reaction. The most efficient catalysts known up‐to‐date for these processes usually contain expensive and scarce elements, substantially impeding implementation of such electrocatalysts at a larger scale. Metal‐organic frameworks (MOFs) and their derivatives containing affordable components and building blocks, as an emerging class of porous functional materials, have been recently attracting a great attention thanks to their tunable structure and composition together with high surface area, just to name a few. Up to now, several MOFs and MOF‐derivatives have been reported as electrode materials for the energy‐related electrocatalytic application. In this review article, we summarize and analyze current approaches to design such materials. The design strategies to improve the Faradaic efficiency and selectivity of these catalysts are discussed. Last but not least, we discuss some novel strategies to enhance the conductivity, chemical stability and efficiency of MOF‐derived electrocatalysts.     

The fabrication strategies and enhanced performances of metal-organic frameworks and carbon dots composites: State of the art review

Metal-organic frameworks (MOFs) with large specific surface area, considerable pore volume, controllable structure, and high concentration of active metal sites have been applied widely in researches like catalysis and sensing. However, potential applications of MOFs in both photocatalysis and luminescence sensors are facing major challenges arising from their severe charge recombination, low utilization of solar energy, low quantum yield, limited charge transfer between the metal ions/clusters and the ligand. Recent studies revealed that rational introduction of carbon dots (CDs) with excellent optical properties, unique quantum confinement and high conductivity can greatly enhance the functions of MOFs. In this paper, typical synthesis methods of these CD-MOF composites as well as their potential applications in photocatalysis and sensing are reviewed with emphasis. Representative examples of these CD-MOF composites are discussed, and key features and advantages of CD-MOF composites that will facilitate future applications are highlighted.     

Impact of Higher‐Order Structuralization on the Adsorptive Properties of Metal–Organic Frameworks

The structural processing of metal–organic frameworks (MOFs) over multiple length scales is critical for their successful use as adsorbents in a variety of emerging applications. Although significant advances in molecular‐scale design have provided strategies to boost the adsorptive capacities of MOFs, relatively little attention has been directed toward understanding the influence of higher‐order structuralization on the material performance. Herein, we present the main strategies that are currently available for the structural processing of MOFs and discuss the influence these processes can impart on the adsorptive properties of the materials. In all, this intriguing area of research is expected to provide significant opportunities to enhance the properties of MOFs further, which will ultimately aid in their optimization in the context of specific real‐world applications.     

Expanded Organic Building Units for the Construction of Highly Porous Metal–Organic Frameworks

Two new organic building units that contain dicarboxylate sites for their self‐assembly with paddlewheel [Cu₂(CO₂)₄] units have been successfully developed to construct two isoreticular porous metal–organic frameworks (MOFs), ZJU‐35 and ZJU‐36, which have the same tbo topologies (Reticular Chemistry Structure Resource (RCSR) symbol) as HKUST‐1. Because the organic linkers in ZJU‐35 and ZJU‐36 are systematically enlarged, the pores in these two new porous MOFs vary from 10.8 Å in HKUST‐1 to 14.4 Å in ZJU‐35 and 16.5 Å in ZJU‐36, thus leading to their higher porosities with Brunauer–Emmett–Teller (BET) surface areas of 2899 and 4014 m² g^?1 for ZJU‐35 and ZJU‐36, respectively. High‐pressure gas‐sorption isotherms indicate that both ZJU‐35 and ZJU‐36 can take up large amounts of CH₄ and CO₂, and are among the few porous MOFs with the highest volumetric storage of CH₄ under 60 bar and CO₂ under 30 bar at room temperature. Their potential for high‐pressure swing adsorption (PSA) hydrogen purification was also preliminarily examined and compared with several reported MOFs, thus indicating the potential of ZJU‐35 and ZJU‐36 for this important application. Studies show that most of the highly porous MOFs that can volumetrically take up the greatest amount of CH₄ under 60 bar and CO₂ under 30 bar at room temperature are those self‐assembled from organic tetra‐ and hexacarboxylates that contain m‐benzenedicarboxylate units with the [Cu₂(CO₂)₄] units, because this series of MOFs can have balanced porosities, suitable pores, and framework densities to optimize their volumetric gas storage. The realization of the two new organic building units for their construction of highly porous MOFs through their self‐assembly with [Cu₂(CO₂)₄] units has provided great promise for the exploration of a large number of new tetra‐ and hexacarboxylate organic linkers based on these new organic building units in which different aromatic backbones can be readily incorporated into the frameworks to tune their porosities, pore structures, and framework densities, thus targeting some even better performing MOFs for very high gas storage and efficient gas separation under high pressure and at room temperature in the near future.     

Advances and challenges of MOF derived carbon-based electrocatalysts and photocatalyst for water splitting: A review

Environmental pollution and energy shortage are substantial fears to the modern world's long-term sustainability. Water splitting is an essential technique for eco - friendly and sustainable energy storage, as well as a pollution-free method to produce hydrogen. In this regards Metal–organic frameworks have emerged as the most competent multifunctional materials in recent times, due to its large surface areas, adjustable permeability, easy compositional alteration, and capability for usage as precursors with a wide range of morphological forms. Further, MOF-derived carbon-based nanomaterials also offer significant benefits in terms of tunable morphological features and hierarchical permeability, as well as ease of functionalization, making them extremely effective as catalysts or catalysts supports for a wide variety of important reactions. Recent developments in carbon-based MOFs as catalysts for overall water splitting are discussed in this review. We explore how MOFs and carbon-based MOFs might well be beneficial, as well as which methods should be explored for future development. We divided our review into two sections: photocatalytic and electrocatalytic water splitting, and we gathered published literature on carbon-based MOFs materials for their outstanding activity, offers helpful methods for catalysts design and analysis, as well as difficulties This study highlights the developments in MOF derived materials as photo and electro catalysts by explaining respective approaches for their use in overall water splitting.