泡沫铜基底原位生长的铜基导电金属有机框架作为双功能电催化剂

以泡沫铜为基底生长氢氧化铜纳米线,通过原位转化合成二维导电金属有机框架(MOF)材料Cu_3HITP_2(HITP=2,3,6,7,10,11-六氨基三亚苯)作为双功能催化剂,可直接用作析氧及氧还原反应的工作电极,而无需使用额外的基底或粘合剂,且无需后续热处理。研究发现以氢氧化铜纳米线为模板的Cu_3HITP_2表现出了更大的电化学比表面积,这种新型的电极可在碱性溶液(0.1和1.0 mol·L~(-1) KOH)中可以稳定运行,析氧反应中在电流密度达到10 mA·cm~(-2)时的过电位仅为1.53 V,超越了商业二氧化钌的催化性能。此外,该催化剂在氧还原反应中的半波电位达到0.75 V,优于大多数MOF材料。     

基于理论指导的电催化剂调控:从机制分析到结构设计（英文）

电催化在许多清洁能源转换技术中起着核心作用,能够与光伏、风电和水电等可再生能源发电系统耦合,解决全球能源和气候危机.一些重要的电化学转化过程,包含析氢反应(HER)、析氧反应(OER)、氧还原反应(ORR)、氮还原反应(NRR)和二氧化碳还原(CO2RR)等,引起了广泛的研究兴趣.实现这些电催化技术大规模应用的核心在于开发先进的电催化材料.传统电催化剂的研发依赖于“试错法”实验合成,这一过程耗时漫长、成本较高.近20年来,基于理论指导的新材料开发成为更先进的电催化剂设计思路,这主要受益于:(1)重要的基本理论、活性描述符与催化剂机制的确立;(2)计算化学在电化学领域的成熟.这些进展揭示了电催化剂的构效规律,加速了电催化剂的研发过程.本文梳理了电催化剂设计理论发展的关键历程.首先,萨巴捷原则指出理想催化剂的吸附应该是“中庸”的:过弱的吸附无法使反应发生,过强的吸附将导致催化剂表面被覆盖而无法进一步反应.火山型曲线准确描绘了这一现象,并为此提供了可定量的数学表达,但仍缺少量化吸附的物理量.随着计算机技术与密度泛函理论的不断发展,人们能够获得吸附能、活化能等微观物理量.同时, Br?nste...     

MOF衍生碳基电催化剂限域催化O2还原和CO2还原反应

化石燃料的大量消耗和环境的逐渐恶化导致迫切需要开发和探索有效的能源转换和存储技术. 电化学是各种能源转换装置的基础和关键. 设计和合成具有高催化活性的非贵金属基和非金属基催化剂是最好的选择. 金属有机骨架(MOF)衍生的碳基材料具有比表面积大、 孔隙率高的特点, 可以选择性地限制不同类型的金属. 因此, MOF衍生碳作为催化剂载体使用时具有良好的限域效应, 有利于提高催化剂的活性和稳定性. 本文综合评述了MOF衍生材料在催化反应中的限域效应, 并介绍了MOF衍生碳基材料在氧还原反应(ORR)和二氧化碳还原反应(CO₂RR)电催化方面的最新进展, 揭示了MOF碳基材料在电催化反应中的构效关系. 最后, 讨论了MOF衍生的碳基材料在ORR和CO₂RR电催化中的挑战和机遇, 以及未来可能的解决方案.     

原位57Fe穆斯堡尔光谱技术及其在Ni-Fe基析氧反应电催化剂中的应用(英文)

近年来,析氧反应(oxygen evolution reaction)中针对高效且具有成本效益的电催化剂开发一直是构筑有效利用可再生能源存储系统和水分解生产清洁氢能燃料的重大障碍。OER过程涉及四电子、四质子耦合并形成氧-氧(O-O)键,因此动力学上进程缓慢。为提升其在水分解产氢及二氧化碳还原反应中的应用,需要开发高效催化剂,降低OER过电位,以减轻能量转换过程中固有的能量损失。研究表明,IrO₂和RuO₂具有较低析氧过电位,但储量低、价格昂贵,大大限制了其在析氧反应中的大规模应用。而Ni-Fe基析氧催化剂在碱性水分解反应中展现了优异的性能,其在水分解过程中的催化机制仍有待进一步研究。为了解决Ni-Fe基催化剂在析氧反应过程中反应位点及催化反应机制等关键问题,迫切需要更先进的原位技术来准确表征,原位追踪催化剂形态变化与电解质/电极之间的界面相互作用的影响。光谱与电化学结合的原位技术可以监测析氧反应过程催化剂自身的变化。目前,已有大量原位光谱技术与电化学进行结合,揭示Ni-Fe基催化剂在OER过程中的反应机理及活性位点,包括原位表面增强拉曼光谱...     

原位组装在碳纸上的有机金属骨架材料衍生的NC/Co/CoP催化剂用于碱性环境水分解（英文）

随着世界工业经济的发展,作为不可再生能源的化石燃料消耗日趋增大并带来严重的环境污染.氢能具有能量密度高、燃烧无污染等优点,被认为是替换传统化石燃料的理想能源之一.通过电化学方法实现水裂解制氢是既满足环境要求又符合氢气生产需要的一种潜在有效方法,受到人们广泛关注.基于铂、钌等贵金属的电催化剂在水裂解中具有很高的活性,然而其稀缺性和高成本是阻碍其大规模实际应用的重要因素.水裂解制氢包括二电子转移的质子还原和四电子转移的水氧化两个过程.相对于质子还原,水氧化反应动力学过程缓慢,是决定水裂解速率的关键.通常,质子还原反应倾向于在酸性条件下进行,而水氧化反应在碱性环境下更有利,反应条件的差异阻碍了水裂解制氢的发展.因此,制备在碱性环境下具有高催化性能、高稳定性和低成本的催化剂是促进水裂解制氢能源技术进一步发展的关键.金属有机骨架(MOF)衍生的复合催化剂具有良好的催化性能和广阔的应用前景,在催化反应中得到越来越多的重视.传统的催化剂组装方式是通过全氟磺酸聚合物等辅助剂将催化剂组装到工作电极上,这些辅助剂具有较强的酸性,而且会覆盖催化剂表面的催化活性位点,降低催化剂比表面积,阻碍催化剂活性的进一步提升.本文通过电泳的方法,将ZIF-67负载到碳纸上,进一步通过碳化、部分磷化过程得到NC/Co/Co P/CP催化电极.研究发现,在碱性环境(1 mol/LKOH)下,催化电流达到10 m A/cm^2的析氢过电位只有208 m V,析氧反应的过电位为350 m V,在二电极体系中所需的电压也只有1.72 V,催化活性明显高于通过传统方法组装的电极.在长时间的电化学稳定性测试中,经过20h的电流测试和1000次的CV测试后,该电极的催化活性没有明显下降.我们报道了一种基于MOF材料的复合电极组装新方法,为MOF材料在能源储存与转化领域应用提供了新思路.     

导电MOFs在能源转化中的应用

可再生能源供应方案包括析氢反应(HER)、析氧反应(OER)、氧还原反应(ORR)和二氧化碳还原反应(CO2RR)等多种反应,电催化剂对这些反应至关重要。到目前为止,已有一系列导电MOFs作为与能源相关电催化电极材料的报道。本文从提高MOFs导电能力和对产物的选择性、增强MOFs的化学稳定性及增加MOFs的反应活性位点等方面介绍了导电MOFs作为电催化剂的设计策略,重点综述了其在能源转化涉及的HER、OER、ORR以及CO2RR方面的应用,并从材料制备和应用需求角度出发, 对高性能导电MOFs材料在电催化领域所面临的挑战和前景进行了展望。     

纤维蛋白原在Pt电极上的界面电化学研究

应用电化学方法和电化学原位红外反射光谱(electrochemical in-situ FTIR)等研究了纤维蛋白原在Pt电极上的界面电化学行为.结果表明:纤维蛋白原在Pt电极上的吸附使电极的析氢与氧脱附过程减弱,影响程度随扫速的增加而增强;同样纤维蛋白原的吸附会降低亚铁氰化钾-铁氰化钾电对的氧化还原反应可逆性和电流;在-0.1~0.6V(vs.SCE)扫描范围内没有出现纤维蛋白原的特征"氧化还原"峰.电化学原位红外反射光谱测试表明纤维蛋白原在0.3~0.5V(vs.SCE)间发生化学反应,有新的产物生成.     

氧在稀土酞菁上的电化学还原

过渡金属大环配合物(例如酞菁和卟啉)对氧的电化学还原具有很高的催化活性,因而是目前电化学最活跃的研究领域之一.关于氧在过渡金属大环配合物上电化学还原机理,一般认为与过渡金属的价态变化有关.近年来,由于稀土双酞菁具有电致变色(electrochromic)的特性,引起了人们极大的兴趣,并对它们的电化学行为进行了一系列的研究,但关于它们对氧的电化学还原作用却未见报道.我们利用循环伏安法研究了某些稀土单酞菁和双酞菁对氧的电化学还原的影响,并提出了氧的电化学还原的反应历程.     

青蒿素及其衍生物电化学性质的研究 Ⅰ.青蒿素在汞电极上的电化学还原

青蒿素及其衍生物代表着一类新型抗疟药.青蒿素分子中过氧基与抗疟活性密切相关.本文采用多种电化学方法研究了青蒿素分子中过氧基在Hg电极上的还原,还原电位在0.OV(vs.Ag/AgCl)附近,电极过程为不可逆还原.反应电子数n=2,半波电位E_(1/2)=0.012V,电子转移系数α=0.66,表观标准电极反应速率常数k_s~’=6.34×10~(-6)cm/s,扩散系数D=4.3×10~(-6)cm~2/s反应产物在电极表面具有吸附性.文中提出了可能的电化学反应机理.     

表面配位金属-有机框架薄膜的制备及电催化应用

设计和开发高效电催化剂对能源的存储和转化具有十分重要的意义.金属-有机框架(MOF)在基底表面通过液相外延层层配位组装的MOF薄膜(也被称作表面配位MOF薄膜,SURMOF)具有厚度可调节、生长取向可控以及表面均匀致密等优点,在电催化反应领域得到了广泛的研究和应用.本文总结了SURMOF及其衍生薄膜(SURMOF-D)...     

Metal-organic framework membranes: From synthesis to electrocatalytic applications

Metal-organic frameworks (MOFs), as an emerging family of porous inorganic-organic crystal materials, exhibit widely applications in gas storage and separation, drug release, sensing, and catalysis, owing to easily adjustable pore sizes, uniformly distributed metal centers, high surface areas, and tunable functionalities. However, MOF crystal powders are usually difficult to be directly applied into specific devices because of their brittleness, insolubility and low compatibility. Therefore, to expand versatile MOF membranes with robustness and operational flexibility is urgent to satisfy practical applications. Although numerous reports have reviewed the synthesis and applications of MOF membranes, relatively few reports the electrocatalytic properties based on MOF membranes. Herein, this mini-review provides an overview of preparation of MOF membranes, including directed synthesis, secondary growth and electrochemical deposition method. Meanwhile, fabrication of ultrathin 2D MOF nanosheets those can be also defined as a kind of nanoscale MOF membranes is also mentioned. Electrocatalytic performance of oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and CO₂ reduction reaction (CO₂RR) for diverse MOF membranes/nanosheets and their derivatives are introduced.     

MOF-Mediated Fabrication of a Porous 3D Superstructure of Carbon Nanosheets Decorated with Ultrafine Cobalt Phosphide Nanoparticles for Efficient Electrocatalysis and Zinc–Air Batteries

Superstructures have attracted great interest owing to their potential applications. Herein, we report the first scalable preparation of a porous nickel-foam-templated superstructure of carbon nanosheets decorated with ultrafine cobalt phosphide nanoparticles. Uniform two-dimensional (2D) Co-metal organic framework (MOF) nanosheets (Co-MNS) grow on nickel foam, followed by a MOF-mediated tandem (carbonization/phosphidation) pyrolysis. The resulting superstructure has a porous 3D interconnected network with well-arranged 2D carbon nanosheets on it, in which ultrafine cobalt phosphide nanoparticles are tightly immobilized. A single piece of this superstructure can be directly used as a self-supported electrode for electrocatalysis without any binders. This “one-piece” porous superstructure with excellent mass transport and electron transport properties, and catalytically active cobalt phosphide nanoparticles with ultrasmall size (3–4 nm), shows excellent trifunctional electrocatalytic activities for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR), achieving great performances in water splitting and Zn–air batteries.     

A Surfactant‐Free and Scalable General Strategy for Synthesizing Ultrathin Two‐Dimensional Metal–Organic Framework Nanosheets for the Oxygen Evolution Reaction

Metal–organic framework (MOFs) two‐dimensional (2D) nanosheets have many coordinatively unsaturated metal sites that act as active centres for catalysis. To date, limited numbers of 2D MOFs nanosheets can be obtained through top‐down or bottom‐up synthesis strategies. Herein, we report a 2D oxide sacrifice approach (2dOSA) to facilely synthesize ultrathin MOF‐74 and BTC MOF nanosheets with a flexible combination of metal sites, which cannot be obtained through the delamination of their bulk counterparts (top‐down) or the conventional solvothermal method (bottom‐up). The ultrathin iron–cobalt MOF‐74 nanosheets prepared are only 2.6 nm thick. The sample enriched with surface coordinatively unsaturated metal sites, exhibits a significantly higher oxygen evolution reaction reactivity than bulk FeCo MOF‐74 particles and the state‐of‐the‐art MOF catalyst. It is believed that this 2dOSA could provide a new and simple way to synthesize various ultrathin MOF nanosheets for wide applications.     

Two-Dimensional MOF and COF Nanosheets: Synthesis and Applications in Electrochemistry

Metal–organic framework (MOF) and covalent organic framework (COF) nanosheets are a new type of two-dimensional (2D) materials with unique design principles and various synthesis methods. They are considered ideal electrochemical devices due to the ultrathin thickness, easily tunable molecular structure, large porosity and other unique properties. There are two common methods to synthesize 2D MOF/COF nanosheets: bottom-up and top-down. The top-down strategy mainly includes ultrasonic assisted exfoliation, electrochemical exfoliation and mechanical exfoliation. Another strategy mainly includes interface synthesis, modulation synthesis, surfactant-assisted synthesis. In this Review, the development of ultrathin 2D nanosheets in the field of electrochemistry (supercapacitors, batteries, oxygen reduction, and hydrogen evolution) is introduced, and their unique dimensional advantages are highlighted.     

Pnictogen (As,Sb, Bi) Nanosheets for Electrochemical Applications Are Produced by Shear Exfoliation Using Kitchen Blenders

Layered materials are of high importance because of their anisotropy and as a source of 2D materials. Whilst there is a plethora of multi‐elemental 2D materials, the number mono‐elemental 2D materials is rather limited. Herein, we demonstrate that aqueous shear exfoliation can be used to obtain As, Sb, and Bi exfoliated nanosheets. Morphological and chemical characterization of the exfoliated materials shows a decrease in thickness, sheet‐to‐nanosheet scale, and partial oxidation owing to a higher surface area. The electrochemical performance is tested in terms of inherent electrochemistry, electron transfer, and sensing applications as demonstrated with ascorbic acid. Potential energy‐related applications are evaluated in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), with shear‐exfoliated Sb having the best electrochemical performance overall. These findings will have a profound impact on the preparation and application of 2D mono‐elemental materials.     

Pnictogen (As,Sb, Bi) Nanosheets for Electrochemical Applications Are Produced by Shear Exfoliation Using Kitchen Blenders

Layered materials are of high importance because of their anisotropy and as a source of 2D materials. Whilst there is a plethora of multi‐elemental 2D materials, the number mono‐elemental 2D materials is rather limited. Herein, we demonstrate that aqueous shear exfoliation can be used to obtain As, Sb, and Bi exfoliated nanosheets. Morphological and chemical characterization of the exfoliated materials shows a decrease in thickness, sheet‐to‐nanosheet scale, and partial oxidation owing to a higher surface area. The electrochemical performance is tested in terms of inherent electrochemistry, electron transfer, and sensing applications as demonstrated with ascorbic acid. Potential energy‐related applications are evaluated in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), with shear‐exfoliated Sb having the best electrochemical performance overall. These findings will have a profound impact on the preparation and application of 2D mono‐elemental materials.     

银纳米粒子修饰的二维金属-有机框架纳米片用于光热增强银离子释放抗菌

近年来,二维(2D)金属-有机框架(MOF)纳米复合材料被广泛的应用于生物医学领域,尤其是在抗菌方面。在此,我们通过光照诱导还银离子成功在二维MOF纳米片上生长银纳米粒子,得到了一种银纳米粒子(Ag NPs)修饰的二维Zr-Fc-MOF (MOF-Ag)纳米片,并将其用于光热增强Ag⁺释放抗菌治疗。通过水热法和超声处理合成MOF纳米片,然后通过原位光辐照诱导还原在MOF纳米片上生长Ag NPs。系列表征结果表明Ag NPs成功负载到MOF纳米片上。聚乙烯吡咯烷酮(PVP)的修饰不仅可以增强MOF-Ag在溶液中的稳定性,还可以增强它的生物相容性。在近红外激光(NIR)照射下,MOF纳米片可以在短时间升温,而温度的升高可以加速Ag NPs在溶液中氧化为银离子。通过细菌生长曲线、菌落相对数和细菌形态变化等实验表明PVP@MOF-Ag纳米片具有优异的广谱杀菌性能。此外,2D MOF纳米片良好的光热性能不仅可以增强Ag⁺的释放,还可以增强细胞膜的通透性,随后进入细菌中的Ag⁺可以诱导内源性活性氧的产生,从而引发细菌的氧化应激,实现高效抗菌。基于良好的体外抗菌性能,进一步将PVP@MOF-Ag纳米片用于小鼠伤口愈合,在此期间PVP@MOF-Ag纳米片表现出良好的治疗效果和生物安全性。我们的研究结果表明,PVP@MOF-Ag纳米片可以作为光热增强Ag⁺释放抗菌治疗和伤口愈合的有效平台。     

Ru-Doping Enhanced Electrocatalysis of Metal–Organic Framework Nanosheets toward Overall Water Splitting

An Ru-doping strategy is reported to substantially improve both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic activity of Ni/Fe-based metal–organic framework (MOF) for overall water splitting. As-synthesized Ru-doped Ni/Fe MIL-53 MOF nanosheets grown on nickel foam (MIL-53(Ru-NiFe)@NF) afford HER and OER current density of 50 mA cm⁻² at an overpotential of 62 and 210 mV, respectively, in alkaline solution with a nominal Ru loading of ≈110 μg cm⁻². When using as both anodic and cathodic (pre-)catalyst, MIL-53(Ru-NiFe)@NF enables overall water splitting at a current density of 50 mA cm⁻² for a cell voltage of 1.6 V without iR compensation, which is much superior to state-of-the-art RuO₂-Pt/C-based electrolyzer. It is discovered that the Ru-doping considerably modulates the growth of MOF to form thin nanosheets, and enhances the intrinsic HER electrocatalytic activity by accelerating the sluggish Volmer step and improving the intermediate oxygen adsorption for increased OER catalytic activity.     

Electric-Field Assisted In Situ Hydrolysis of Bulk Metal–Organic Frameworks (MOFs) into Ultrathin Metal Oxyhydroxide Nanosheets for Efficient Oxygen Evolution

Facile preparation of low-cost electrocatalysts for efficient oxygen evolution reaction (OER) remains a big challenge. Herein, a novel strategy for ultrafast (20 s) transformation of bulk metal–organic frameworks (MOFs) into ultrathin metal oxyhydroxide nanosheets for efficient OER has been developed. For two isomeric MOFs ( FJI-H25Fe and FJI-H25FeCo ), only the metastable FJI-H25FeCo bulk can immediately transform into FeCo-oxyhydroxides nanosheets through electric-field assisted hydrolysis. The potential evolution process from MOF bulk to FeCo-oxyhydroxides nanosheets has been investigated in detail. The as-made nanosheets exhibit excellent OER performances, showing an extremely low overpotential of 231 mV at the current density of 10 mA cm⁻², a relatively small Tafel slope of 42 mV dec⁻¹, and long-term durability of at least 30 h. This work not only provides a novel strategy for facile preparation of low-cost and efficient OER electrocatalysts, but also represents a new way for preparation of metal oxyhydroxides nanosheets with good crystallinity and morphology, and a fresh method for mild synthesis of nanosized derivatives from MOF materials.     

Electric‐Field Assisted In Situ Hydrolysis of Bulk Metal–Organic Frameworks (MOFs) into Ultrathin Metal Oxyhydroxide Nanosheets for Efficient Oxygen Evolution

Facile preparation of low‐cost electrocatalysts for efficient oxygen evolution reaction (OER) remains a big challenge. Herein, a novel strategy for ultrafast (20 s) transformation of bulk metal–organic frameworks (MOFs) into ultrathin metal oxyhydroxide nanosheets for efficient OER has been developed. For two isomeric MOFs ( FJI‐H25Fe and FJI‐H25FeCo ), only the metastable FJI‐H25FeCo bulk can immediately transform into FeCo‐oxyhydroxides nanosheets through electric‐field assisted hydrolysis. The potential evolution process from MOF bulk to FeCo‐oxyhydroxides nanosheets has been investigated in detail. The as‐made nanosheets exhibit excellent OER performances, showing an extremely low overpotential of 231 mV at the current density of 10 mA cm^?2, a relatively small Tafel slope of 42 mV dec^?1, and long‐term durability of at least 30 h. This work not only provides a novel strategy for facile preparation of low‐cost and efficient OER electrocatalysts, but also represents a new way for preparation of metal oxyhydroxides nanosheets with good crystallinity and morphology, and a fresh method for mild synthesis of nanosized derivatives from MOF materials.