可控形貌的双金属纳米晶催化剂的研究进展

本文在简要介绍双金属纳米晶的结构类型的基础上,总结了近年来所发展的控制双金属纳米晶形貌的主要合成方法,并探讨了它们在燃料电池以及固液气催化反应中的应用前景。     

Pt/Au双金属纳米微粒的催化性能

制备了不同比例的Pt/Au双金属纳米微粒,应用UV-VIS、TEM等手段对其结构进行了表征,并比较了它们对丁醛氢化还原反应的催化活性.     

Rh/Co双金属纳米颗粒的制备及其催化制氢性能

以ISOBAM-104为保护剂,采用共还原法制备了一系列不同组成的Rh/Co双金属纳米颗粒(BNPs)。采用紫外-可见吸收光谱、透射电镜及高分辨透射电镜对纳米颗粒的结构及组成进行了表征。结果表明,所制备的Rh/Co BNPs的粒径小于6.0nm,具有合金结构。催化制氢实验结果表明,Rh_(20)Co_(80)BNPs具有最高的催化制氢活性,其TOF值可高达12880mol-H_2·h~(-1)·mol-Rh~(-1),远高于Rh和Co单金属纳米颗粒的催化活性。     

含Co或Ni的双金属及三金属纳米颗粒制备方法及其催化制氢性能

常见的氢气储存方法有液态储氢、高压气态储氢、有机化合物储氢、金属氢化物储氢、吸附储氢及液相化学储氢材料储氢等,其中液相化学储氢材料由于具有含氢量高、且可按时即需释放氢气的优点,引起了研究人员的广泛关注;选择合适的催化剂催化液相储氢材料制氢已成为一个研究热点。含有Co或Ni的双金属或三金属纳米颗粒是一种极具应用前景的催化剂,具有价格低廉、储量丰富和催化性能优异等众多优点。本文综述了含Co或Ni的双金属或三金属纳米颗粒的制备方法及其催化制氢性能,并提出了其目前研究中存在的问题和未来潜在的发展方向。     

置换反应制备Pd-Fe双金属催化剂及其催化加氢性能

以Fe(CO)5为前体采用超声法合成纳米Fe胶体粒子,通过Fe胶体与PdCl2发生金属置换反应制备出活性炭负载Pd-Fe双金属催化剂.研究了表面活性剂聚乙烯吡咯烷酮对制备负载型催化剂的影响.采用XRD、H2程序升温还原(H2-TPR)、TEM、EDX等表征手段对催化剂进行表征,以苯乙炔加氢反应为探针反应考察了Fe含量对于催化剂催化性能的影响.结果表明加氢催化活性较差的金属组分Fe在合适的比例下可以促进Pd基催化剂的加氢催化活性和选择性,然而,过多的Fe也会降低其催化活性.     

尺寸比例可调的Au-Ni双金属纳米颗粒的制备

本文采用贵金属诱导还原法制备了一种Ni端尺寸可调的Au-Ni双金属纳米颗粒.该反应以十八胺为还原剂,硝酸镍和氯金酸为反应物,反应中Au3+首先被还原成Au0,随着温度上升,Ni2+从Au0获得电子而被还原成Ni0,十八胺持续提供电子,得到了雪人状的Au-Ni双金属纳米颗粒.采用I2/KI水溶液和0.5%(质量分数)盐酸分别对Au端和Ni端进行择性蚀刻,通过调节蚀刻时间,连续调控两端尺寸,可以达到完全刻蚀,最终制备了一种两端尺寸比例连续可调的Au-Ni双金属纳米颗粒.蚀刻后得到的新鲜表面为进一步功能复合提供了反应场所.     

纳米铜催化剂在有机反应中的应用

包括铜及其化合物在内的纳米铜催化剂具有催化活性高、应用范围广、环境友好、价格低廉、能多次循环利用等优点,受到了有机化学研究人员越来越多的重视。本文介绍了近年来纳米铜催化剂在有机合成中的应用,包括形成C-C/N/O/S/Se键、成环以及加氢脱氢等一系列反应。     

双金属催化剂催化间苯氧基苯甲醛加氢反应

利用硼氢化钠还原含其它金属盐的氯铂酸形成双金属合金纳米催化剂.Ru和Co的加入能提高催化剂的活性,当Pt/Ru摩尔比为5∶1、Pt/Co摩尔比为7∶1时,双金属协同效应最明显;Cu、Au、Ni的加入不同程度的降低了催化剂的活性.对Pt/Ru和Pt/Co体系,PVP的含量和反应温度都对催化反应的活性有影响.     

置换反应制备Pd-Fe双金属催化剂及其催化加氢性能

以Fe(CO)5为前体采用超声法合成纳米Fe胶体粒子,通过Fe胶体与PdCl2发生金属置换反应制备出活性炭负载Pd-Fe双金属催化剂。研究了表面活性剂聚乙烯吡咯烷酮对制备负载型催化剂的影响。采用XRD、H2程序升温还原（H2-TPR）、TEM、EDX等表征手段对催化剂进行表征,以苯乙炔加氢反应为探针反应考察了Fe含量对于催化剂催化性能的影响。结果表明加氢催化活性较差的金属组分Fe在合适的比例下可以促进Pd基催化剂的加氢催化活性和选择性,然而,过多的Fe也会降低其催化活性。     

电位置换反应在空心结构Pt基燃料电池纳米催化剂中的研究进展

Pt基催化剂是质子交换膜燃料电池难以替代的催化剂,然而低储量高成本的Pt严重制约其商业化进程。如何在减少贵金属Pt用量的同时提高其电催化性能是该领域的核心问题之一。空心结构纳米催化剂活性面积大,催化活性高,稳定性好且显著减少贵金属的用量,其制备方法众多,其中电位置换法无需额外的去核、无需对模板表面进行功能化且易于控制,是制备空心结构纳米材料的主要方法。本文综述了近年来国内外利用电位置换反应制备空心Pt基纳米催化剂的最新进展,并对其发展和应用前景进行了展望。     

In Situ Formation of Liquid Metals via Galvanic Replacement Reaction to Build Dendrite-Free Alkali-Metal-Ion Batteries

Galvanic replacement reactions have been studied as a versatile route to synthesize nanostructured alloys. However, the galvanic replacement chemistry of alkali metals has rarely been explored. A protective interphase layer will be formed outside templates when the redox potential exceeds the potential windows of nonaqueous solutions, and the complex interfacial chemistry remains elusive. Here, we demonstrate the formation of room-temperature liquid metal alloys of Na and K via galvanic replacement reaction. The fundamentals of the reaction at such low potentials are investigated via a combined experimental and computational method, which uncovers the critical role of solid-electrolyte interphase in regulating the migration of Na ions and thus the alloying reaction kinetics. With in situ formed NaK liquid alloys as an anode, the dendritic growth of alkali metals can be eliminated thanks to the deformable and self-healing features of liquid metals. The proof-of-concept battery delivers reasonable electrochemical performance, confirming the generality of this in situ approach and design principle for next-generation dendrite-free batteries.     

炭负载Pd/Ce双金属催化剂对Heck反应的催化性能

通过简便的方法制备了炭负载Pd/Ce双金属催化剂,利用Pd/Ce双金属催化剂的协同效应提高催化剂对Heck反应的催化效率。 以碘苯与丙烯酸的Heck芳基化反应为模型反应,研究了反应条件对催化剂催化性能的影响。 结果显示,在反应温度为130 ℃,反应时间为5 h,N,N-二甲基甲酰胺(DMF)作为溶剂和三丁胺(Bu₃N)作为碱的条件下,炭负载Pd/Ce双金属催化剂对丙烯酸和碘苯的Heck芳基化反应具有良好的催化性能,产率达到70%以上。 另外,该催化剂属于非均相催化剂,催化剂易与反应溶液分离;也可以重复利用,使用3次反应产率仍达到66.9%,显示了炭负载Pd/Ce双金属催化剂良好的催化活性。     

In Situ Formation of Liquid Metals via Galvanic Replacement Reaction to Build Dendrite‐Free Alkali‐Metal‐Ion Batteries

Galvanic replacement reactions have been studied as a versatile route to synthesize nanostructured alloys. However, the galvanic replacement chemistry of alkali metals has rarely been explored. A protective interphase layer will be formed outside templates when the redox potential exceeds the potential windows of nonaqueous solutions, and the complex interfacial chemistry remains elusive. Here, we demonstrate the formation of room‐temperature liquid metal alloys of Na and K via galvanic replacement reaction. The fundamentals of the reaction at such low potentials are investigated via a combined experimental and computational method, which uncovers the critical role of solid‐electrolyte interphase in regulating the migration of Na ions and thus the alloying reaction kinetics. With in situ formed NaK liquid alloys as an anode, the dendritic growth of alkali metals can be eliminated thanks to the deformable and self‐healing features of liquid metals. The proof‐of‐concept battery delivers reasonable electrochemical performance, confirming the generality of this in situ approach and design principle for next‐generation dendrite‐free batteries.     

The Fourth Alloying Mode by Way of Anti‐Galvanic Reaction

Anti‐galvanic reaction (AGR) not only defies classic galvanic theory but is a promising method for tuning the compositions, structures, and properties of noble‐metal nanoparticles. Employing AGR for the preparation of alloy nanoparticles has recently received great interest. Herein, we report an unprecedented alloying mode by way of AGR, in which foreign atoms induce structural transformation of the mother nanoparticles and enter the nanoparticles in a non‐replacement fashion. A novel, active‐metal‐doped, gold nanoparticle was synthesized by this alloying mode, and its structure resolved. A CdSH motif was found in the protecting staples of the bimetal nanoparticle. DFT calculations revealed that the Au₂₀Cd₄(SH)(SR)₁₉ nanoparticle is a 8e superatom cluster. Furthermore, although the Cd‐doping does not essentially alter the absorption spectrum of the mother nanocluster, it distinctly enhances the stability and catalytic selectivity of the mother nanoclusters.     

贵金属固体催化剂的纳米结构及催化性能

 综述了贵金属催化剂纳米结构的形成和制备方法,以及催化活性与纳米粒子尺寸的关系. 还以负载型双金属催化剂为例,介绍了催化剂中的短程有序结构.     

Au-Pt催化剂的控制合成及其对乙醇电氧化性能

乙醇电氧化（EOR）是直接乙醇燃料电池和电解乙醇制氢共有的阳极反应.Au@Pt核壳和AuPt合金是广泛使用的两种电催化材料,迄今尚无两者对EOR性能的对比研究.以CO作为还原剂和淬灭剂合成了近似Pt单层的Au@Pt/C催化剂,作为对照,以NaBH₄还原法合成了相同Au∶Pt物质的量比和金属载量的AuPt/C催化剂;运用透射电子显微镜（TEM）、扫描透射电子显微镜-能谱仪（STEM-EDS）、X射线粉末衍射（XRD）和X射线光电子能谱（XPS）等手段综合表征了两者结构之差异,同时以电化学循环伏安法和计时电流法测试了在碱性体系中其对EOR的电催化性能.结果表明,相比于商业化的Pt/C和Au/C,Au@Pt/C和AuPt/C对EOR的活性和稳定性均有着显著提升;Au@Pt/C对EOR的电催化活性和对C-C键断裂能力略优于AuPt/C.双金属催化剂中Au与Pt之间的晶格应力和部分电荷转移等效应可能是其性能提升的主要原因.     

Synthesis and Characterization of Pd@MxCu1−x (M=Au,Pd, and Pt) Nanocages with Porous Walls and a Yolk–Shell Structure through Galvanic Replacement Reactions

This paper describes the synthesis of Pd@M_xCu_1?x (M=Au, Pd, and Pt) nanocages with a yolk–shell structure through galvanic replacement reactions that involve Pd@Cu core–shell nanocubes as sacrificial templates and ethylene glycol as the solvent. Compared with the most commonly used templates based on Ag, Cu offers a much lower reduction potential (0.34 versus 0.80 V), making the galvanic reaction more easily to conduct, even at room temperature. Our structural and compositional characterizations indicated that the products were hollow inside, and each one of them contained porous M–Cu alloy walls and a Pd cube in the interior. For the Pd@Au_xCu_1?x yolk–shell nanocages, they displayed broad extinction peaks extending from the visible to the near‐IR region. Our mechanistic study revealed that the dissolution of the Cu shell preferred to start from the slightly truncated corners and then progressed toward the interior, because the Cu {100} side faces were protected by a surface capping layer of hexadecylamine. This galvanic approach can also be extended to generating other hollow metal nanostructures by using different combinations of Cu nanostructures and salt precursors.     

Mannich反应合成3,6(8)-二取代-2,4-二氢-1,3-苯并(口恶)嗪及其杀菌活性

以取代苯酚、多聚甲醛和取代苯胺为原料,在无催化剂的条件下,通过Mannich缩合反应合成了一系列新型3,6(8)-二取代-2,4-二氢-1,3-苯并(口恶)嗪类化合物.结果表明,取代苯酚和取代苯胺的取代基为供电子基时,合成产物的产率高于吸电子取代基的.产物的结构用1H NMR、13C NMR、IR和MS等进行了表征.初步测试了目标化合物的杀菌活性,部分化合物具有较好的杀菌活性.当浓度为25 mg/L时,化合物4j和4d对菌核病菌的抑制率分别为86.1％和81.5％,化合物4i对灰霉病菌的抑制率为81.6％.