MoS2-石墨烯的制备及其电催化析氢性能的研究

本文利用改进的Hummers方法合成层状的石墨烯,并用原位合成法在石墨烯上负载了颗粒状二硫化钼。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线光电子能谱分析仪(XPS)、粉末X-射线衍射仪(XRD)、比表面及孔隙度分析仪对所合成物质的形貌、结构、比表面积及孔径进行分析;使用电化学工作站测试催化剂的线性循环伏安和Tafel曲线来分析所合成催化剂的电化学析氢性能。结果表明在所有样品中石墨烯/二硫化钼-21.7复合物的电催化性能最好,其在电流密度为-10 mA·cm~(-2)时过电位为-193 mV。     

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

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...     

磁场对铁卟啉仿生催化性能的影响

在生命体中,细胞色素P－450单充氧酶辅基是具有铁Df琳结构的血红素．用金属叶琳作为细胞色素P－450单充氧酶的模型化合物探讨和研究人类生命现象一直是国内外化学仿生催化领域极为感兴趣的研究内容之一［’1．我们曾用p一氧代双铁叶琳作为细胞色素P－450单充氧酶的模型化合物,发现改变金属叶琳结构和金属原子电子自旋态将会引起金属叶琳磁性改变,而金属叶琳磁性改变会进一步导致金属叶琳仿生催化性能发生改变D”‘．我们认为,这一现象与人类和地球构成的生物圈可能有某些关联．为了考察地球磁场对人类生命现象的影响,我们进一步建立…     

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.     

原子数精确的金属纳米团簇在电催化领域的应用研究进展

金属纳米团簇（M NCs）是由几个到数百个金属原子组成,其尺寸一般小于2 nm。金属纳米团簇在许多催化反应中表现出高的催化活性和选择性,这与金属纳米团簇具有高的比表面积、较多暴露的活性原子,以及与金属纳米粒子（M NPs）不同的电子结构有关。金属纳米团簇确定的组成和结构使其成为一种新型模型催化剂,对纳米团簇的催化性能研究有利于人们深入理解催化剂结构-性质之间的关系,更利于催化剂的理性设计与发展。结合近几年国内外和本课题组在金属纳米团簇电催化领域的研究进展和现状,本文对该领域的代表性工作进行了简要综述,并对其未来在电催化领域的应用前景和需要解决的关键问题进行了展望。     

Ni-Fe/Ti和Ni-Fe-S/Ti的制备及其电催化水分解性能

以钛网为基底,采用电沉积法制备了Ni-Fe/Ti析氧电极,然后将得到的Ni-Fe/Ti电极通过固相硫化制备了Ni-Fe-S/Ti析氢电极. 分别考察了电沉积液中Ni ²⁺/Fe ³⁺离子摩尔浓度比和硫脲加入量对Ni-Fe/Ti和Ni-Fe-S/Ti结构和电化学性能的影响. 结果表明,随着电沉积液中Ni ²⁺含量的增加,Ni-Fe/Ti电极析氧性能先增强后减弱,Ni9Fe1/Ti电极具有最好的析氧性能;随着硫脲加入量的增加,Ni-Fe-S/Ti电极析氢性能呈现先增强后减弱的趋势,Ni9Fe1S0.25/Ti电极具有最好的析氢性能. 在50 mA·cm ^-2下,Ni9Fe1/Ti电极的析氧过电位为280 mV,Ni9Fe1S0.25/Ti电极的析氢过电位为269 mV,且均具有很好的稳定性. 将Ni9Fe1/Ti与Ni9Fe1S0.25/Ti分别作为阳极和阴极进行电催化全水分解,电流密度达到50 mA·cm ^-2所需电势仅1.69 V,表现出很好的全水解催化性能.     

磷化钴@铁-锌双金属磷化物多级纳米复合物的制备及其电催化水分解性能

氢能源因其储量丰富、高效、零污染等特性而受到广泛关注.电解水产氢作为一种有效的获取氢能源的方式成为当前研究的重点.但由于电极表面反应过电势的存在极大增加了电解水的能耗,因此需要开发高效的电催化材料以提高电解水反应动力学.考虑到实际应用,设计和构筑在同一电解液中同时具有高效催化产氢和释氧能力的双功能催化材料更为重要且更具挑战.目前,越来越多的非贵金属基双功能催化材料被开发和报道,比如过渡金属硫化物、氧化物、层状双金属氢氧化物、碳化物、氮化物和磷化物等,其中又以磷化物的研究更为广泛.金属有机骨架化合物(MOFs)因其具有独特的性能(孔隙率高、超高比表面积、可调控的化学组分和孔道结构等)在能源转化等领域得到广泛应用.但是,基于MOFs材料转化的多组分过渡金属磷化物应用于全分解水体系的报道还比较少.先前的研究表明,优化催化材料的微纳结构和化学组成是提高材料催化性能的关键.我们利用三步法(晶体生长、自组装和磷化)设计并制备了一种基于MOFs转化的新型分级纳米复合材料CoP@ZnFeP.透射电子显微镜(TEM)结果显示,自组装形成的花状Co3O4@Fe-MOF-5中空结构在磷化后形貌能够很好地保持.X射线衍射(XRD)表明, CoP@ZnFeP纳米复合物是由大量的混合纳米晶体组成,主要包括Co2P, ZnP2和Fe2P.在碱性(1.0mol/L KOH)条件下, CoP@ZnFeP纳米复合物表现出优异的催化产氢(HER)和释氧(OER)性能,其释氢和产氧的启动电位分别为–50和148m V(vs.RHE),相应的Tafel斜率分别为76和53.9m V/decade.优异的电催化性能主要归功于复合材料的多级纳米结构组元(纳米粒子、纳米笼和纳米管),其有序的多孔结构和大的比表面积有利于电解液的渗透、气体的扩散和电子的转移.作为对比,我们利用相似方法制备了CoP和ZnFeP纳米粒子的机械混合物(CoP/ZnFeP).测试数据表明, CoP@ZnFeP分级复合材料的催化性能优于CoP/ZnFeP机械混合物.鉴于CoP@ZnFeP复合材料优异的催化性能,我们将其应用于全分解水体系.在两电极体系中,达到10m A/cm~2电流密度仅需1.6V电压,表明材料具有优异的全分解水性能.同时该复合物也显示出较好的稳定性,经过24h连续水解后,电解电位仅升高70m V.但同时我们也注意到电极表面剧烈产生的气泡会对电极材料的稳定性有严重影响.此项研究可为设计高效的非贵金属催化材料应用于能源转化和储存等领域提供较好的思路和借鉴.     

溶解-再生长法构建Fe-Dy氧化物调控镍-有机框架电子结构的高性能水分解电催化剂

世界经济的快速发展加剧了能源消耗,迫切需要探索替代的可持续能源,以减少对化石燃料的依赖.电化学水分解制氢由于具有较高的能量密度,是一种很有应用前景的可再生、环境友好的能源,也被认为是最有潜力的储能和转化方法之一.为了实现高效和经济的水电解,必须制备高活性、低成本和合适的析氧反应(OER)电催化剂.OER是水分解的半反应...     

Application of metal chalcogenide-based anodic electrocatalyst toward substituting oxygen evolution reaction in water splitting

Electrochemical water splitting for producing hydrogen has received increasing attention. However, the large overpotential of oxygen evolution reaction (OER) is a bottleneck in water splitting. Exploiting value-added alternative reactions to replace the OER semi-reaction in water splitting can not only produce valuable products at both electrodes, but also reduce the overpotential of water splitting. Recently, metal chalcogenides (sulfides and selenides) have been widely studied in electrocatalytic reactions. This review concentrates on the recent application of metal chalcogenides in value-added anodic reactions by replacing the OER during electrochemical water splitting, including urea oxidation reaction (UOR), 5-hydroxymethylfurfural electrochemical oxidation reaction (HMF-EOR), which provides the guidance for the rational design of advanced metal chalcogenide electrocatalysts in renewable energy.     

非晶纳米材料用于电解水的研究进展

电催化水分解产氢作为一种有前途的制氢技术被全世界研究者广泛关注.然而,此领域仍然缺少一种高效、无污染的催化剂,以降低能耗,提升反应动力学,进而推进电解水的实际应用.近年来研究发现,具有短程有序、长程无序特征的非晶纳米材料在电解水领域表现出极其优异的性能.有趣的是,固有的无序结构赋予了非晶纳米材料丰富的高活性位点.鉴于此...     

The effect of magnetic field on the stability of (18-crown-6) complexes with potassium ion

Macrocyclic polyethers are ligands with selectivity for metal ions. In order to understand the interactions between ligand, ion and solvent we resorting to study of magnetic field effect on ion-macrocyclic complexes. Therefore, we studied the complexation between 18-crown-6 and potassium ion in water through the conductometry technique (in 25+0.05 °C) by a nonlinear least-square program (Genplot) under magnetic field.We observed that stability constants of complexes in the presence of the magnetic field, were decreased. Like-wise, we observed that, magnetic field influenced on ion, solvent and ligand one by one.     

How to minimise destabilising effect of gas bubbles on water splitting electrocatalysts?

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Use of magnetic fields in electrochemistry: A selected review

Electrochemical reactions are usually thermally activated and submitted to mass-transfer effects. Although classically, enhanced kinetics of an electrochemical reaction is obtained by heating the cell and feeding the reactant by forced convection, other means can be used to improve mass-transfer and charge-transfer. This article shortly reviews the effects of magnetic fields in electrochemistry. Using a static or an alternating magnetic field enables to enhance electrodeposition and electrocatalysis, via improved gas and species convection, electrochemical kinetics, and whole reaction efficiency. Such enhancement can mainly be related to Lorentz and Kelvin forces, magneto-hydrodynamics, chiral-induced spin selectivity, and hyperthermia, these effects being described herein.     

Atomically dispersed Mn enhanced catalytic performance for overall water splitting on graphdiyne-coated copper hydroxide nanowire

Atomic catalysts(ACs)have been considered as promising catalysts for efficient hydrogen production through water splitting.Herein,we report an AC with single Mn atoms highly dispersed on the surface of graphdiyne-coated copper hydroxide nanowire arrays(Mn-GDY/Cu(OH)x NWs).By anchoring Mn atoms on GDY,the specific surface area,the number of active sites,and the stability of catalyst are greatly improved.Detailed characteri-zations reveal that the high hydrogen and oxygen evolution reaction(HER/OER)catalytic activity of the catalyst is induced by strong incomplete charge transfer effect between the metal atoms and GDY.These advantages enable the electrocatalysts to drive a current density of 10 mA cm-2 at low overpotentials of 188 and 130 mV for OER and HER,respectively,together with excellent long-term stability.Remarkably,the alkaline electrolyzer using Mn-GDY/Cu(OH)x as both cathode and anode electrodes can reach 10 mA cm-2 only at a much low cell voltage of 1.50 V.     

光催化分解水制氢反应中助催化剂的作用及机理（英文）

近年来,随着一次能源过度消耗所带来的能源和环境问题日益突出,开发廉价、可持续的清洁能源备受关注.光催化分解水制氢可利用太阳能普遍率高和几乎免费等特点制取燃烧热值高、燃烧产物无污染的氢气能源.自从1972年日本的Fujishima教授和Honda教授首次发现TiO₂单晶电极光催化分解水可以产生氢气以来,光催化制氢被认为是实现可持续制氢最有潜力的方法之一.有效地将太阳能转换为化学能的关键是设计高效的电荷分离和运输结构.然而,现有的大多数半导体光催化剂因缺少活性位点、光生载流子易复合等缺点而无法达到较高的转换效率.因此,如何提高半导体光催化产氢的转换效率是现阶段面对的重要问题.在众多解决方法中,助催化剂的引入可以为光催化制氢反应增加活性位点,促进光生载流子的有效分离,进而有效地提高半导体光催化产氢速率.本文总结了多种不同类型的助催化剂应用于光催化产氢研究的最新进展,详细讨论了助催化剂在增强光吸收、提供活性位点、增加催化剂稳定性和促进电荷分离等方面的作用,阐明了助催化剂在光催化分解水制氢中的反应机理,同时还提出了光催化制氢的未来研究和预测.本文将助催化剂分为以下几种类别进...     

Electronic structure and visible light photocatalysis water splitting property of chromium-doped SrTiO3

Cr-doped SrTi_1−xCr_xO₃ (x=0.00, 0.02, 0.05, 0.10) powders, prepared by solvothermal method, were further characterized by ultraviolet-visible (UV-vis) absorption spectroscopy. The UV-vis spectra indicate that the SrTi_1−xCr_xO₃ powders can absorb not only UV light like pure SrTiO₃ powder but also the visible-light spectrum (λ>420 nm). The results of density functional theory (DFT) calculation illuminate that the visible-light absorption bands in the SrTi_1−xCr_xO₃ catalyst are attributed to the band transition from the Cr 3d to the Cr 3d+Ti 3d hybrid orbital. The photocatalytic activities of chromium-doped SrTiO₃ both under UV and visible light are increased with the increase in the amounts of chromium.     

Stability and crystal field splitting of N inf2 sup− in Barium Azide

The crystal field splitting of the ground²_g state and the equilibrium orientation of the N _inf2 ^sup– radical in the monoclinic barium azide are calculated employing a point ion representation of the lattice potential and assuming three different plausible trapping sites for the radical. When the N _inf2 ^– is assumed to replace an azide ion which is parallel to thec axis of the unit cell, the previously suggested trapping site, the calculated crystal field splitting is in order of magnitude agreement with the value deduced from theg shift in the ESR spectrum. The calculated orientational angle of the molecular axis with thec axis of the unit cell is 9.0 degrees which compares favorably with the experimentally determined angle of 5.0 ± 1.5 degrees. Possible reasons why the N _inf2 ^– can not be trapped at the site of an azide ion which is perpendicular to the c axis are suggested from the calculation.