通过与氧化石墨烯复合增强金属有机框架材料MOF(Ni)-74的电催化析氢性能

采用溶剂热法制备了金属有机框架材料MOF(Ni)-74及其与氧化石墨烯(GO)的复合材料MOF(Ni)-GO,并利用线性伏安扫描(LSV)等电化学方法在N_2饱和的0.5mol/L H_2SO_4溶液中对材料的电催化性能进行了检测。实验结果表明,GO的掺杂能显著提升金属有机框架材料MOF(Ni)-74的电催化活性。其中GO含量为8%时,所得复合材料表现出最好的电催化析氢活性,起始电势仅为-0.462V,塔菲尔斜率为110mV/dec,同时该材料也表现出很好的电化学稳定性。     

多孔Ni-WC复合电极的制备及其在酸性溶液中的电催化析氢性能

目前,关于多孔Ni-WC电极的电催化析氢(HER)性能的报道较少。以多孔海绵镍为基体,采用复合电沉积制备多孔Ni-(WC)x复合电极。运用扫描电镜(SEM)和X射仪线衍射仪(XRD)表征电极的表面形貌和微观结构,通过阴极极化、电化学阻抗(EIS)、循环伏安、计时电流法研究多孔Ni-(WC)x电极在0.5 mol/L H2SO4溶液中的电催化析氢性能。结果表明:与多孔基体Ni电极相比,多孔Ni-(WC)x电极具有较低的析氢过电位、较低的电化学反应阻抗、较小的表观活化能以及较大的交换电流密度;随着镀液中WC浓度的升高,所制备的多孔Ni-(WC)x电极的电催化析氢活性增强,其中Ni-(WC)40电极的表观交换电流密度是多孔Ni基体电极的966.7倍,其表观活化能为5.95 kJ/mol,并具有较好的耐蚀性和析氢稳定性。     

多糖/金属有机框架(MOFs)复合气凝胶的制备及应用进展

气凝胶材料是一类具有三维纳米结构的多孔材料,在航空航天、石油化工、环保工程、建筑工程、化学催化、医药卫生等领域表现出广泛的应用价值,自问世以来一直深受人们的关注.由纤维素、壳聚糖、海藻酸等多糖制备得到的气凝胶材料不仅能够保持传统气凝胶高孔隙率、大比表面积、低密度的特点,还具备了天然高分子可再生、可降解、生物兼容性好的优点,成为了当前的热门材料之一.金属有机框架(MOFs)是一类由金属节点以及有机配体通过配位作用组装形成的多孔框架材料,在吸附、催化、传感、载药等领域都表现出巨大的应用潜力.随着对材料应用功能、加工性能、循环使用性能等要求的提升,近年来人们对多糖/MOFs复合气凝胶材料的研究兴趣逐渐高涨.自2016年第一例纤维素纳米晶/MOFs复合气凝胶材料被报道以来,研究人员尝试了多种不同的多糖以及MOFs组合,制备了不同类型的多糖/MOFs复合气凝胶材料,并探索了它们在不同领域的应用.本文首先总结了多糖/MOFs复合气凝胶材料的三种常见制备策略:(1)将预先制备好的MOFs与多糖直接混合制备复合气凝胶;(2)在多糖分子表面原位生成MOFs之后再制备复合气凝胶;(3)在已制备好的多糖气凝胶中原位生成MOFs再制备复合气凝胶.通过相应的实例详细介绍了这些制备方法的特点,然后分别介绍了多糖/MOFs复合气凝胶材料在不同领域中的应用情况,最后针对当前该领域研究存在的不足以及面临的问题提出了解决方法并展望了未来可能的发展方向.     

金属有机框架材料MIL-53(Al)-F127对双酚A的吸附性能

采用一步溶剂热法制备具有介孔结构金属有机框架材料MIL-53(Al)-F127，用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶红外变换光谱仪(FTIR)、全自动比表面积及孔隙度分析仪(BET)等手段表征其形貌和结构，探究其对双酚A(BPA)的吸附性能并与微孔结构的MIL-53(Al)对比，研究了吸附剂的含量、pH以及温度对其吸附性能的影响。结果表明，介孔结构金属有机框架材料MIL-53(Al)-F127对双酚A具有良好的吸附性能；在pH值为6、温度为30℃条件下MIL-53(Al)-F127在20 min左右达到最大平衡吸附量为27.2 mg/g，去除率达到92%。其吸附动力学模型拟合结果，符合准二级动力学曲线。     

Ni (OH)2-碳纳米管-还原氧化石墨烯复合材料的制备及电化学性能

利用简单易行的一步水热法制备了Ni（OH）₂-碳纳米管-还原氧化石墨烯（Ni（OH）₂-CNTs-RGO）三元复合材料,研究了不同水热反应温度对三元复合材料性能的影响。采用XRD、FTIR、Raman、X射线光电子能谱（XPS）、SEM及TEM对Ni（OH）₂-CNTs-RGO复合材料的结构和表面微观形貌进行表征。利用循环伏安（CV）、电化学交流阻抗（EIS）和恒电流充放电测试了复合电极材料的电化学性能。研究结果表明,当反应温度为120℃时,所制备的Ni（OH）₂-CNTs-RGO复合材料具有大的比表面积和三维网状结构,复合材料中六角形的β-Ni（OH）₂纳米片和CNTs均匀分散在RGO片层表面,有效阻止了RGO的团聚。Ni（OH）₂-CNTs-RGO复合电极材料在充电倍率为0.2 C时,放电比容量达到362.8 mAh/g,5 C时放电比容量为286.2 mAh/g,仍大于Ni（OH）₂在0.2 C时的放电比容量,表明CNTs与RGO的协同作用有效提高了电极材料的导电性和活性物质的利用率,最终提升了Ni（OH）₂-CNTs-RGO复合材料的倍率性能。     

氧化石墨烯/金属-有机框架复合材料在光催化中的应用

光催化因其绿色安全、环境友好、成本低廉等优势,被认为是解决当前世界范围内环境问题和能源危机的有效方法.光催化技术的核心之一是光催化材料的研发,制备光催化活性高、组成稳定、可回收再利用的光催化剂是许多研究者的共同追求.近年来,金属-有机框架(MOFs)作为一类新型光催化材料已被广泛关注,但是由于结构不稳定、容易聚集、光生电子空穴对极易复合等缺点,其光催化效果受到严重影响,限制了MOFs在实际生产生活中的应用.因此,找到一种简便实用的方法来改善MOFs的光催化性能具有十分重要的意义.经实验证实,将氧化石墨烯(GO)与MOFs复合是有效方法之一.GO表面丰富的含氧基团使其易与MOFs复合,GO稳定的二维平面结构能增强MOFs的结构稳定性,同时GO极强的亲水能力还使MOFs容易分散在溶剂中.此外,更值得一提的是GO/MOF复合材料的电子-空穴复合速率得到有效降低,相比于母体组分其光催化活性显著提升.该方法易于操作、成本低廉,且对多种MOFs都有较好的适用性.本文综述了GO/MOF复合材料的最新进展,重点介绍了此类复合材料作为光催化剂在去除环境污染物中的应用,包括去除气态污染物、还原重金属离子、降解抗生素类药物、降解有机染料和降解其他有机污染物等方面.最后对GO/MOF复合材料未来的发展趋势作出预测,以期推动MOFs新型复合材料应用于环境修复.     

A Metal-Organic Framework (MOF) Fenton Nanoagent-Enabled Nanocatalytic Cancer Therapy in Synergy with Autophagy Inhibition

Nanocatalytic medicine has been developed recently to trigger intratumoral generation of highly toxic reactive oxygen species (ROS) for cancer therapy, which, unfortunately, suffers from compromised therapeutic efficacy due to a self-protective mechanism, autophagy, of cancer cells to mitigate oxidative damage. In this work, during the efforts of ROS generation by nanocatalytic medicine, a pharmacological autophagy inhibition strategy is implemented for augmenting ROS-induced oxidative damage for synergetic cancer therapy. An iron-containing metal-organic framework [MOF(Fe)] nanocatalyst as a peroxidase mimic is used to catalyze the generation of highly oxidizing •OH radicals specifically within cancer cells, while chloroquine is applied to deacidify lysosomes and inhibit autophagy, cutting off the self-protection pathway under severe oxidative stress. Cancer cells fail to extract their components to detoxicate and strengthen themselves, finally succumbing to the ROS-induced oxidative damage during nanocatalytic therapy. Both in vitro and in vivo results demonstrate the synergy between nanocatalytic therapy and autophagy inhibition, suggesting that such a combined strategy is applicable to amplify tumor-specific oxidative damage and may be informative to future design of therapeutic regimen.     

Enhanced the Efficiency of Electrocatalytic CO2-to-CO Conversion by Cd Species Anchored into Metal-Organic Framework

Metal-organic frameworks (MOFs) as a promising platform for electrocatalytic CO₂ conversion are still restricted by the low efficiency or unsatisfied selectivity for desired products. Herein, zirconium-based porphyrinic MOF hollow nanotubes with Cd sites (Cd-PCN-222HTs) are reported for electrocatalytic CO₂-to-CO conversion. The dispersed Cd species are anchored in PCN-222HTs and coordinated by N atoms of porphyrin structures. It is discovered that Cd-PCN-222HTs have glorious electrocatalytic activity for selective CO production in ionic liquid-water (H₂O)-acetonitrile (MeCN) electrolyte. The CO Faradaic efficiency (FE_CO) of >80% could be maintained in a wide potential range from −2.0 to −2.4 V versus Ag/Ag⁺, and the maximum current density could reach 68.0 mA cm⁻² at −2.4 V versus Ag/Ag⁺ with a satisfied turnover frequency of 26 220 h⁻¹. The enhanced efficiency of electrocatalytic CO₂ conversion of Cd-PCN-222HTs is closely related to its hollow structure, anchored Cd species, and good synergistic effect with electrolyte. The density functional theory calculations indicate that the dispersed Cd sites anchored in PCN-222HTs not only favor the formation of *COOH intermediate but also hinder the hydrogen evolution reaction, resulting in high activity of electrocatalytic CO₂-to-CO conversion.     

A Highly Conductive MOF of Graphene Analogue Ni3(HITP)2 as a Sulfur Host for High‐Performance Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have been considered as one of the most promising energy storage systems owing to their high theoretical capacity and energy density. However, their commercial applications are obstructed by sluggish reaction kinetics and rapid capacity degradation mainly caused by polysulfide shuttling. Herein, the first attempt to utilize a highly conductive metal–organic framework (MOF) of Ni₃(HITP)₂ graphene analogue as the sulfur host material to trap and transform polysulfides for high‐performance Li–S batteries is made. Besides, the traditional conductive additive acetylene black is replaced by carbon nanotubes to construct matrix conduction networks for triggering the rate and cycling performance of the active cathode. As a result, the S@Ni₃(HITP)₂ with sulfur content of 65.5 wt% shows excellent sulfur utilization, rate performance, and cyclic durability. It delivers a high initial capacity of 1302.9 mAh g^?1 and good capacity retention of 848.9 mAh g^?1 after 100 cycles at 0.2 C. Highly reversible discharge capacities of 807.4 and 629.6 mAh g^?1 are obtained at 0.5 and 1 C for 150 and 300 cycles, respectively. Such kinds of pristine MOFs with high conductivity and abundant polar sites reveal broad promising prospect for application in the field of high‐performance Li–S batteries.     

Using Graphene Oxide to Enhance the Barrier Properties of Poly(lactic acid) Film

The ultra‐thin (polyethyleneimine/graphene oxide)_n [(PEI/GO)_n]multilayer films on poly(lactic acid) (PLA) were constructed via the layer‐by‐layer assembly. Here, the electrostatic interactions between PEI and GO were used to obtain the nanoscale composite membrane of (PEI/GO)_n on the surface of PLA film. With the number of assembling layers increased, the oxygen permeability (PO₂) of PLA film decreased substantially. As a 0.06 wt% GO solution was used with only four layers, the PO₂ decreased from 53.8 to 0.377 × 10^?4 cm³/m²/d/Pa, only 0.7% of the original PLA film. At the same time, the coated PLA film also presented a good transparency and better mechanical properties. It is a novel way to use GO on biodegradable packaging materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Graphene growth on Ni(111) by transformation of a surface carbide

A novel growth mechanism of graphene on Ni(111) has been discovered that occurs at temperatures below 460 °C. At these conditions, a surface-confined nickel-carbide phase coexists with single layer graphene. The graphene grows by in-plane transformation of the carbide along a one-dimensional phase-boundary, which is distinctively different from known growth processes on other transition metals and on Ni above 460 °C, where carbon atoms attach to "free" edges of graphene islands.