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。     

MOF衍生的Ni/C的制备及其氮还原性能研究

电催化氮气还原反应(NRR)因可在常温常压下高效固氮而被认为是一种前景广阔的合成氨的方法，有望替代传统Haber-Bosch工艺。电催化剂的设计和制备是提升NRR性能的关键因素。采用水热法制备了金属-有机框架材料(MOF),通过高温热处理获得MOF衍生的片状Ni/C纳米材料，将其用于NRR反应的电催化剂。研究发现，在0.1mol/L KOH电解液中，电位为-0.9V时Ni/C纳米材料最大的氨产率为66.57μg/(h·mg),法拉第效率高达33.67%,且显示了良好的电化学稳定性。     

离子液体/金属-有机骨架复合材料制备方法、理论计算及应用研究进展

金属-有机骨架(MOF)是一种多孔、高比表面积的新型纳米材料.离子液体(IL)具有稳定性好、功能可设计的特点,将IL负载到MOF的孔中,实现离子液体和MOF材料的有效组合,开发新型功能化复合多孔材料,有利于充分发挥两种材料的优势.本文主要介绍IL/MOF复合材料合成方法、分子模拟及其应用的最新研究.总结目前IL/MOF...     

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。     

Al掺杂Ni(OH)2的结构及充放电性能

为了改善Ni(OH)2的电化学性能,提高锌镍电池的充放电效率,用简便的化学共沉淀法合成了Al掺杂的Ni(OH)2.用XRD、FTIR表征了合成掺杂Al的Ni(OH)2样品的晶体结构及IR光谱特征;测试了用Al掺杂的Ni(OH)2为正极活性物质的Zn/Ni实验电池的充放电性能.研究结果表明:所合成的Al掺杂Ni(OH)2具有α-Ni(OH)2的晶体结构;Al掺杂Ni(OH)2活性物质在充放电过程中转移电子数目大于1,Al掺杂Ni(OH)2作为正极活性物质的Zn/Ni试验电池的第二次循环放电比容量为362.9mAh/g.     

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.     

Ni(OH)_2/RGO复合材料的化学沉淀-回流法制备和放电性能

以氧化石墨(GO)和NiSO_4·6H_2O为前驱体,氨水为沉淀剂,用化学沉淀-回流法制备Ni(OH)_2/还原氧化石墨烯(RGO)复合材料,用XRD、SEM表征材料的结构和表面微观形貌,用循环伏安(CV)、恒电流充放电和电化学阻抗(EIS)测试电极材料的电化学性能,研究了GO:Ni(OH)_2质量比和氨水浓度对复合材料结构、形貌和电化学性能的影响。结果表明:所制备的β-Ni(OH)_2/RGO复合材料为Ni(OH)_2纳米片与RGO片相互插层的结构,当氨水的浓度为3 mol/L,GO:Ni(OH)_2=1:8(质量比)时复合电极材料在0.2C的放电比容量高达334.9 mAh/g,5C的放电比容量为260.2 mAh/g,保持在β-Ni(OH)_2理论比容量的90%,表现出良好的倍率性能和循环性能。     

具有高比电容的纳米Ni-MOF/GO的制备及赝电容特性研究

以不同温度和不同制备时间作为实验条件，采用溶剂热法制备了1^#、2^#、3^#三类Ni-MOF材料。然后，将MOF材料中的3^#和氧化石墨烯(GO)等多孔碳材料复合，测得其具有优异的电化学性能。3^#在50mA/g时的比电容达700F/g,在500mA/g通过100次循环后仍有电容为222F/g,可保持3^#器件初始电容的58.9%以上。3^#/GO在500mA/g时表现出412F/g的高质量比电容，并且在100次循环后，保持其初始电容的72%以上。该器件的最大能量密度和最大功率密度分别为11.58Wh/kg和46.32W/kg。通过X射线衍射、X射线光电子能谱技术、比表面积和氮气吸脱附、红外光谱和扫描电子显微镜等测试，证实了GO能显著地改善MOF赝电容的电化学性能。     

AgI/NH2-UiO-66(Zr)异质结制备及其可见光催化性能

开发可见光响应型金属有机框架材料(MOFs)异质结,有望高效利用太阳能进行催化降解/减毒环境污染物。以氯化锆(ZrCl₄)和2-氨基对苯二甲酸(2-ATA)为原料,用溶剂热法制备了NH₂-UiO-66(Zr)作为基底MOFs,采用对离子沉淀法在其表面负载AgI,制备一系列AgI/NH₂-UiO-66(Zr)异质结复合光催化剂。通过XRD、BET、TEM、UV-Vis DRS、FT-IR、TGA及光电化学测试等手段对材料进行结构和光电响应性质表征。以Cr(VI)为模型污染物,探究复合材料在可见光照射下的光催化性能,以及影响其性能的各种因素：pH、初始Cr(VI)浓度、催化剂投加量、捕获剂种类及浓度。实验结果显示：当AgI负载量为20%时,优选得到的AgI/NH₂-UiO-66(Zr)具有最佳的光催化性能,可见光照射120 min后,Cr(VI)还原率为97.8%,远高于纯AgI和NH₂-UiO-66(Zr),拟合的一级动力学常数k分别是AgI和NH₂-UiO...     

FeOOH-Ni(OH)2复合材料的制备及其电催化析氧性能

以碳纤维布（CFC）为基底,通过两步法(恒电流电沉积法、溶剂热法)成功制备了FeOOH-Ni(OH)₂复合材料。与FeOOH和Ni(OH)₂相比,该FeOOH-Ni(OH)₂复合材料作为电催化剂时,电催化析氧反应(OER)活性显著提高。在1 mol/L KOH电解质溶液中,达到10 mA·cm?2电流密度时所需要的过电位仅为270 mV,Tafel斜率为78 mV/dec,电化学阻抗谱进一步揭示了电解过程中良好的动力学特性。FeOOH-Ni(OH)₂复合材料在碱性介质中具有优异的稳定性,其在高电流密度下(50 mA·cm?2)的过电势经过连续24 h的测试之后几乎没有发生明显变化。FeOOH和Ni(OH)₂之间的强电子相互作用和协同效应有效提高了电导性,促进了电荷转移;此外,这种核壳结构有效增强了电催化活性面积,进而增强了其电催化析氧性能。      

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。     

Size dependence electrocatalytic activity of gold nanoparticles decorated reduced graphene oxide for hydrogen evolution reaction

It is promising for AuNPs/RGO composites to be exploited for hydrogen evolution reaction (HER), due to the collaborative effects between the electrocatalytic Au nanoparticles (AuNPs) and conductive reduced graphene oxide (RGO). In this work, we used a simple way to decorate AuNPs onto the RGO surface by one pot in situ reduction both HAuCl₄ and GO, for which the controlled average size of AuNPs (2.7, 11.5 and 45.7 nm) is adjusting with the mass ratio of HAuCl₄ and GO. The obtained materials, AuNPs/RGO composites, show excellent electrocatalytic activity for the HER that critical dependence on the particle size of AuNPs. The results show that AuNPs/RGO with AuNPs size of 11.5 nm exhibits superior electrochemical activity: low onset potential of 0.029 V versus the reversible hydrogen electrode as well as a small Tafel slope of 86 mV per decade.     

Self‐Sacrificial Template‐Directed Vapor‐Phase Growth of MOF Assemblies and Surface Vulcanization for Efficient Water Splitting

Direct use of metal–organic frameworks (MOFs) with robust pore structures, large surface areas, and high density of coordinatively unsaturated metal sites as electrochemical active materials is highly desirable (rather than using as templates and/or precursors for high‐temperature calcination), but this is practically hindered by the poor conductivity and low accessibility of active sites in the bulk form. Herein, a universal vapor‐phase method is reported to grow well‐aligned MOFs on conductive carbon cloth (CC) by using metal hydroxyl fluorides with diverse morphologies as self‐sacrificial templates. Specifically, by further partially on‐site generating active Co₃S₄ species from Co ions in the echinops‐like Co‐based MOF (EC‐MOF) through a controlled vulcanization approach, the resulting Co₃S₄/EC‐MOF hybrid exhibits much enhanced electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of 84 and 226 mV required to reach a current density of 10 mA cm^?2, respectively. Density functional theory (DFT) calculations and experimental results reveal that the electron transfer between Co₃S₄ species and EC‐MOF can decrease the electron density of the Co d‐orbital, resulting in more electrocatalytically optimized adsorption properties for Co. This study will open up a new avenue for designing highly ordered MOF‐based surface active materials for various electrochemical energy applications.     

Inlaying Ultrathin Bimetallic MOF Nanosheets into 3D Ordered Macroporous Hydroxide for Superior Electrocatalytic Oxygen Evolution

Controllable synthesis of ultrathin metal–organic framework (MOF) nanosheets and rational design of their nano/microstructures in favor of electrochemical catalysis is critical for their renewable energy applications. Herein, an in situ growth method is proposed to prepare the ultrathin NiFe MOF nanosheets with a thickness of 1.5 nm, which are vertically inlaid into a 3D ordered macroporous structure of NiFe hydroxide. The well‐designed composite delivers an efficient electrocatalytic performance with a low overpotential of 270 mV at a current density of 10 mA cm^?2 and stable electrolysis as long as 10 h toward the electrochemical oxygen evolution reaction, much superior to the state‐of‐the‐art RuO₂ electrocatalyst. A comprehensive analysis demonstrates that the excellent performance originates from the desirable combination of the highly exposed active centers in the ultrathin bimetallic MOF nanosheets, effective electron conduction between MOF nanosheets and ordered macroporous hydroxide, and efficient mass transfer across the hierarchically porous hybridization. This study sheds light on the exploration of powerful protocols to gain diverse high‐performance MOF nanosheets and may open a perspective to achieve their efficient electrocatalytic performance.     

A Freestanding 3D Heterostructure Film Stitched by MOF-Derived Carbon Nanotube Microsphere Superstructure and Reduced Graphene Oxide Sheets: A Superior Multifunctional Electrode for Overall Water Splitting and Zn–Air Batteries

Developing a scalable approach to construct efficient and multifunctional electrodes for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is an urgent need for overall water splitting and zinc–air batteries. In this work, a freestanding 3D heterostructure film is synthesized from a Ni-centered metal−organic framework (MOF)/graphene oxide. During the pyrolysis process, 1D carbon nanotubes formed from the MOF link with the 2D reduced graphene oxide sheets to stitch the 3D freestanding film. The results of the experiments and theoretical calculations show that the synergistic effect of the N-doped carbon shell and Ni nanoparticles leads to an optimized film with excellent electrocatalytic activity. Low overpotentials of 95 and 260 mV are merely needed for HER and OER, respectively, to reach a current density of 10 mA cm⁻². In addition, a high half-wave potential of 0.875 V is obtained for the ORR, which is comparable to that of Pt/RuO₂ and ranks among the top of non-noble-metal catalysts. The use of an “all-in-one” film as the electrode leads to excellent performance of the homemade water electrolyzer and zinc–air battery, indicating the potential of the film for practical applications.     

In-situ formed NiS/Ni coupled interface for efficient oxygen evolution and hydrogen evolution

High-performance electrocatalysts for water splitting are desired due to the urgent requirement of clean and sustainable hydrogen production.To reduce the energy barrier,herein,we adopt a facile in-situ surface modification strategy to develop a low-cost and efficient electrocatalyst for water splitting.The synthesized mulberry-like NiS/Ni nanoparticles exhibit excellent catalytic performance for water splitting.Small overpotentials of 301 and 161 mV are needed to drive the current density of 10 mA cm~(-2) accompanying with remarkably low Tafel slopes of 46 and 74 mV dec~(-1) for oxygen evolution reaction(OER) and hydrogen evolution reaction(HER),respectively.Meanwhile,a robust electrochemical stability is demonstrated.Further high-resolution X-ray photoelectron spectroscopy analyses reveal that the intrinsic HER activity improvement is attributed to the electron-enriched S on the strongly coupled NiS and Ni interface,which simultaneously facilitates the important electron transfer,consistent with the electrochemical impedance results.The post characterizations demonstrate that surface reconstructed oxyhydroxide contributes to the OER activity and NiS/Ni is an OER precatalyst.This structure construction with in-situ formation of active interface provides an effective way to design efficient electrocatalysts for energy conversion.     

水热合成镍铜复合磷化物及其电催化析氢与肼氧化性能

以镍网(NM, Nickel Mesh)为基体、NaH₂PO₂·H₂O为磷源、CuSO₄·5H₂O为铜源、NiSO₄·6H₂O为镍源, 采用一步水热法合成镍铜磷复合电催化剂, 对制备工艺进行优化, 并通过不同方法进行形貌、结构、组成和电催化性能表征。结果表明：当溶液中镍、铜、磷的配比为8: 1 :20时, 在140 ℃水热合成24 h, 制得主晶相为Ni₂P和Cu₃P、具有三级微纳结构的镍铜磷复合电催化剂。在电流密度为10 mA·cm ^-2时, NiCuP/NM的催化析氢及肼氧化过电势分别为165和49 mV; 在双电极体系中, 同电流密度下的分解槽压仅为0.750 V, 催化24 h后分解槽压几乎保持不变, 展现出优异的催化稳定性。无论三电极体系还是双电极体系均表现出优异的催化活性。分析认为, 电催化活性面积为空白镍网的近14倍, 为电催化过程提供了大量的活性位点; 掺入P改变了Ni、Cu原子的电子结构, 提高了材料的本征肼氧化活性, 两者的协同作用促进了电催化活性的提升。本研究为纳米尺度的合成提供了一个新的视角, 有望推动新型纳米孔结构材料在燃料电池和传感器应用中的发展。     

脱合金化制备纳米多孔Ni-Fe合金及其电催化性能

采用真空熔炼与固溶相结合的方法获得原子分数为Ni_30-xFe_xMn₇₀(x=0,10,20)的前驱体合金,通过脱合金化方法制备纳米多孔Ni及Ni-Fe合金,采用X射线衍射(XRD)、扫描电子显微镜(SEM)分析合金相组成和微观结构,运用线性扫描伏安法、交流阻抗、方波电位法及计时电位法研究电极的析氢电催化性能。结果表明:加入Fe获得了片状结构的纳米多孔Ni-Fe合金,提高了纳米多孔Ni的表面积,且Fe与Ni产生协同效应,能够有效提高合金的析氢电催化活性。当Fe含量为10%(原子分数)时,脱合金化得到的纳米多孔Ni-Fe合金表面积最大,析氢电催化性能最好,在0.1A/cm^2电流密度下,析氢过电位仅56mV,经10h连续电解,表现出良好的电催化活性和电化学稳定性。     

非晶Nd-Ni-B/NF稀土复合电极材料的制备及其析氢性能

本研究采用简单的一步化学沉积法制备非晶纳米Nd-Ni-B/NF稀土复合电极并研究其析氢(Hydrogen evolution reaction, HER)性能。通过各种测试方法对纳米电极材料进行物相分析和形貌表征,并探索其电催化析氢性能和稳定性。结果表明, 稀土Nd可提高电极的电催化析氢性能, 当硝酸钕浓度为3 g?L^-1时, 恒温35 ℃下施镀1 h, 制备的Nd-Ni-B/NF电极析氢性能最佳。Nd-Ni-B/NF(Nickel foam)电极在1.0 mol?L^-1KOH 溶液中, 20 mA?cm^-2电流密度下的析氢过电位仅为180 mV, Tafel斜率为117 mV?dec^-1, 析氢反应由Volmer-Heyrovsky步骤控制。此外, Nd-Ni-B/NF电极具有优越的电化学稳定性, 在持续电解12 h或2000次循环伏安测试后, 催化剂的活性没有明显衰减。