纳米TiO2薄膜光阳极的制备及性能

本文以钛酸正丁酯为前驱物、乙醇作为分散剂、二乙醇胺作为螯合剂、聚乙二醇作为表面活性剂,采用溶胶-凝胶法制备得到一种TiO2溶胶,并通过乙酸或氨水作用后制得另外两种溶胶,分别在室温于ITO导电玻璃上涂制,得到5种单一粒径范围纳米TiO2薄膜和具有两种粒径范围膜层的6种纳米TiO2薄膜;XRD和SEM等测试结果表明,纳米TiO2薄膜为锐钛矿相或锐钛矿与金红石相的混合相,其粒径分布范围在15～30nm,30～50 nm,40～80 nm区间。采用浸渍法将所制备的膜进行染料的敏化,得到染料敏化纳米TiO2薄膜半导体光阳极,测试结果表明,在所制备的纳米TiO2薄膜中,具有两种粒径范围膜层的纳米TiO2薄膜的光电性能相对较好。     

二氧化钛纳米管阵列薄膜的超声辐射阳极氧化制备

通过使用铂片作为对电极在含有氢氟酸的二甲基亚砜溶液中, 将金属钛片进行阳极氧化的方法制备得到二氧化钛纳米管阵列薄膜. 在施加40 V偏压超声辐射作用下阳极氧化24 h条件下得到的二氧化钛纳米管长达到680 nm, 管内直径25 nm, 管壁厚度约3～5 nm. 采用了XRD和TEM等分析手段表征了二氧化钛纳米管阵列薄膜的微观结构和表面形貌, 分别测试了薄膜的光吸收性能、循环伏安特性和光化学转换效率, 并和碱性溶胶-凝胶方法制备的纳米晶二氧化钛薄膜作了对比研究. 实验制备的二氧化钛纳米管阵列薄膜电极的光吸收率比纳米晶二氧化钛薄膜提高了40%, 光电化学转换效率前者是后者的6倍, 实验结果表明二氧化钛纳米管阵列薄膜结构有利于加快电子的传输, 并能减少电荷复合, 采用这种二氧化钛纳米管阵列薄膜结构的染料敏化太阳能电池光电极有望进一步提高太阳能电池的效率. 本文还探讨了在超声波辐射作用下二氧化钛纳米管阵列薄膜的形成机理.     

CoFe2-xRExO4(RE=Tb,Dy)纳米晶薄膜的化学合成及磁性

以溶胶-凝胶法制备了稀土铽或镝掺杂的钴尖晶石铁氧体纳米晶薄膜.考察了Tb或Dy的掺杂量及晶化条件对晶相的影响.结果表明,稀土离子的掺杂量x超过0.3时,样品很难形成尖晶石单相.原子力显微镜对纳米晶薄膜表面形貌的观测显示,溶胶-凝胶法制备的薄膜粒度可控制在20～50nm,且具有较高的表面平整度.对于厚度为200nm的薄膜,均方根粗糙度仅为4～5nm.磁特性研究发现,掺杂Tb或Dy的样品矫顽力明显提高.     

分级骨架和多层的Pt-Ni纳米晶体用于高效氧还原和甲醇氧化反应

燃料电池是电动汽车和电子设备最有前途的清洁能源之一.Pt催化剂在氧还原反应(ORR)和甲醇氧化反应(MOR)中的电催化性能对电池系统的能源效率和电池的价格起着至关重要的作用,因此设计高效的电催化剂以最大限度地提高铂的利用率,从而增强电催化效果、降低成本,已经成为燃料电池发展的一个重要方向.早期的研究表明,铂基催化剂可以有效地提高电催化性能,并且它们的组成和形貌被认为是影响催化剂活性的两个关键因素.至今,已合成出各种各样的Pt基催化剂,如Pt-Pb/Pt核壳纳米盘、Pt3Co凹面立方体、Pt-Cu-Rh纳米笼、Pt-Pd纳米枝晶等,其中纳米枝晶结构的催化剂表现出很好的氧还原性能,其高效的催化活性被认为是暴露出的较高的比表面积促进了电子转移以及拥有较多的Pt活性位点.本文采用简单的溶剂热法合成了具有大比表面积的Pt-Ni分层骨架结构(Pt-Ni HSNs)催化剂,为了验证反应物所起的作用,通过收集不同反应时间下的产物和控制单一变量,我们发现在合成配方中加入H2SO4是此类Pt-Ni纳米晶体成功生长的关键触发因素.在H2SO4的诱导下,Pt和Ni原子倾向于沉积在(111)面,促使Pt-Ni合金沿晶面方向生长为八面体结构,在此过程中发生了粒子自组装成长以及相分离过程,最后我们用酸蚀法制造了Pt-Ni HSNs,并通过TEM,XRD和XPS表征其微观结构及组成,证实了Pt-Ni HSNs已经形成合金结构.在酸性条件下,Pt-Ni HSNs在ORR反应中展示出比商业Pt/C更好的活性.在0.9 V时的质量活性为1.25 A mgpt–1,是商业Pt/C质量活性的8.9倍,并且在10000圈的耐久性测试中,Pt-Ni HSNs的质量活性仅仅损失了21.6％,远低于Pt/C损失的活性比例.Tafel曲线和旋转环盘测试结果表明,Pt-Ni HSNs在ORR反应中发生的是4电子过程,证实了它的高活性.另外,在酸性溶液中,Pt-Ni HSNs表现出了比商业Pt/C更好的MOR催化活性,且抗CO中毒能力更强.这可归因于两点:(1)Pt-Ni HSNs是由多个小颗粒组装而成,大大提高了与电解液的接触面积;(2)它独特的骨架结构减少了颗粒间团聚的可能性,有利于质子的转移.本文为设计先进的铂基电催化剂提供了一种新的自组装方法.     

分级骨架和多层的Pt-Ni纳米晶体用于高效氧还原和甲醇氧化反应

燃料电池是电动汽车和电子设备最有前途的清洁能源之一.Pt催化剂在氧还原反应(ORR)和甲醇氧化反应(MOR)中的电催化性能对电池系统的能源效率和电池的价格起着至关重要的作用,因此设计高效的电催化剂以最大限度地提高铂的利用率,从而增强电催化效果、降低成本,已经成为燃料电池发展的一个重要方向.早期的研究表明,铂基催化剂可以有效地提高电催化性能,并且它们的组成和形貌被认为是影响催化剂活性的两个关键因素.至今,已合成出各种各样的Pt基催化剂,如Pt-Pb/Pt核壳纳米盘、Pt3Co凹面立方体、Pt-Cu-Rh纳米笼、Pt-Pd纳米枝晶等,其中纳米枝晶结构的催化剂表现出很好的氧还原性能,其高效的催化活性被认为是暴露出的较高的比表面积促进了电子转移以及拥有较多的Pt活性位点.本文采用简单的溶剂热法合成了具有大比表面积的Pt-Ni分层骨架结构(Pt-Ni HSNs)催化剂,为了验证反应物所起的作用,通过收集不同反应时间下的产物和控制单一变量,我们发现在合成配方中加入H2SO4是此类Pt-Ni纳米晶体成功生长的关键触发因素.在H2SO4的诱导下,Pt和Ni原子倾向于沉积在(111)面,促使Pt-Ni合金沿晶面方向生长为八面体结构,在此过程中发生了粒子自组装成长以及相分离过程,最后我们用酸蚀法制造了Pt-Ni HSNs,并通过TEM,XRD和XPS表征其微观结构及组成,证实了Pt-Ni HSNs已经形成合金结构.在酸性条件下,Pt-Ni HSNs在ORR反应中展示出比商业Pt/C更好的活性.在0.9 V时的质量活性为1.25 A mgpt–1,是商业Pt/C质量活性的8.9倍,并且在10000圈的耐久性测试中,Pt-Ni HSNs的质量活性仅仅损失了21.6％,远低于Pt/C损失的活性比例.Tafel曲线和旋转环盘测试结果表明,Pt-Ni HSNs在ORR反应中发生的是4电子过程,证实了它的高活性.另外,在酸性溶液中,Pt-Ni HSNs表现出了比商业Pt/C更好的MOR催化活性,且抗CO中毒能力更强.这可归因于两点:(1)Pt-Ni HSNs是由多个小颗粒组装而成,大大提高了与电解液的接触面积;(2)它独特的骨架结构减少了颗粒间团聚的可能性,有利于质子的转移.本文为设计先进的铂基电催化剂提供了一种新的自组装方法.     

纳米Au-TiO2复合薄膜的溶胶-凝胶法制备、表征和性能

用溶胶-凝胶法制备了纳米Au-TiO₂复合薄膜.X射线衍射、X射线光电子能谱、原子力显微镜、紫外-可见光谱及摩擦磨损实验研究表明,复合薄膜均匀致密,Au以纳米晶粒形式均匀、不连续分散镶嵌于TiO₂基体中,纳米Au粒径为14～25nm;复合薄膜在可见光区有较强的吸收,吸收峰位置和强度与烧结温度和金的添加量有关;复合薄膜具有良好的抗磨减摩性能,在1N负荷下,摩尔分数为5%的Au-TiO₂薄膜的摩擦系数仅为0.09～0.10,耐磨寿命多于2000滑动周次.     

铁酸镧纳米晶薄膜制备及其在MOS场效应晶体管气敏元件上的应用

纳米晶固体材料是由粒径小于100nm的微晶颗粒聚集而成的块状或薄膜人工固体,它具有特殊性能。本文采用sol-gel法制备了LaFeO_3纳米晶薄膜,并与集成电路平面工艺相结合,首次研制出了用纳米晶薄膜作为栅控制极的MOS场效应晶体管乙醇敏感元件。     

CoNi-PVP复合催化剂的制备及对乙醇电催化氧化性能研究

采用还原-高分子稳定剂(PVP)络合保护的方法制备用于催化乙醇氧化的纳米复合材料CoNi-PVP.通过红外光谱(IR)、透射电镜(TEM)、扫描电镜能谱(SEM-EDS)等技术对纳米复合催化材料进行表征.结果显示,得到的产物为Co,Ni纳米线,直径3～5 nm,长度约100 nm.利用循环伏安和计时电流法测试了其在碱性介质中对乙醇电化学氧化的催化能力.CoNi-PVP-C电极中的Co、Ni金属含量为2%,PVP∶CoNi物质量比为5∶1时,对乙醇的电化学氧化有最佳催化活性.     

水热合成微孔纳米羟基磷灰石

以Ca(NO3)2·4H2O、P2O5为原料,水-乙醇为溶剂,在碱性介质中,采用水热法合成微孔纳米羟基磷灰石晶体(HAP),研究了水-乙醇的体积比对产物组成、晶体结构的影响. 利用X射线衍射(XRD)、红外光谱(FTIR)、热分析(TG/DTA)、透射电镜(TEM)等检测技术对HAP的晶相、化学组成和形貌进行了表征和分析. 结果表明,当V(水):V(乙醇)=1:1时,可得到晶体发育完整、晶体表面孔洞分布均匀(孔密度约为3×109个/cm2)和孔径约为1～2 nm的六方柱状纳米羟基磷灰石晶体(60 nm×100 nm).     

聚苯胺纳米颗粒的制备及其电化学性能

以乙醇和水为混合溶剂,采用氧化法制备了纳米尺度的聚苯胺颗粒。采用扫描电镜、红外光谱、循环伏安、恒流充放电及交流阻抗等测试手段对其结构和电化学性能进行了测试。研究了混合溶剂的比例对产物电化学性能的影响。结果表明：聚苯胺颗粒大小为50～100 nm;以制备的聚苯胺纳米颗粒为活性物质,在1 mol/L的H2SO4电解液中,当...     

碱性介质中多孔纳米结构镍/钯-镍电极上甲醇电氧化反应(英文)

A nanostructured Ni/Pd-Ni catalyst with high activity for methanol oxidation in alkaline solution was prepared by electrodeposition followed by galvanic replacement, that is, electrodeposition of Ni-Zn on a Ni coating with subsequent replacement of the Zn by Pd at the open circuit potential in a Pd-containing alkaline solution. The surface morphology and composition of the coatings were examined by energy dispersive X-ray spectroscopy and scanning electron microscopy. The Ni/Pd-Ni coatings were porous and were composed of discrete Pd nanoparticles of about 58 nm. The electrocatalytic activity of the Ni/Pd-Ni electrodes for the oxidation of methanol was examined by cyclic voltammetry and electrochemical impedance spectroscopy. The onset potentials for methanol oxidation on Ni/Pd-Ni were 0.077 V and 0.884 V, which were lower than those for flat Pd and smooth Ni electrodes, respectively. The anodic peak current densities of these electrodes were 4.33 and 8.34 times higher than those of flat Pd (58.4 mA/cm2 vs 13.47 mA/cm2) and smooth Ni (58.4 mA/cm2 vs 7 mA/cm2). The nanostructured Ni/Pd-Ni electrode is a promising catalyst for methanol oxidation in alkaline media for fuel cell application.     

钯纳米线电极的制备及其应用于乙醇的电化学氧化研究

纳米线作为纳米科学领域中的重要一员,因其优异的光学、电学及磁学等特性引起了凝聚态物理学界、化学界以及材料科学界科学家们的极大关注,并己成为当今纳米科技研究的热点领域[1].纳米线的制备方法有多种,本文提及的模板法制备纳米线结构技术是20世纪90年代初发展起来的一种既经济又简便实用的新工艺[2].     

Electrocatalytic Oxidation of Ethanol on Flexible Three‐dimensional Interconnected Nickel/Gold Composite Foams in Alkaline Media

In this work, a porous and flexible three‐dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (～100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in‐situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ～0.63 V) in comparison with pristine NiF for ethanol oxidation are demonstrated. This potential is lower than many reported results except palladium‐ and platinum‐based catalysts, which are expensive. It is shown that both hydroxyl anions and cations affect the ethanol oxidation on the 3D electrode. The interconnected porous structure provides efficient mass diffusivity, which along with its high specific surface area combined with the catalytic nature of AuNPs, may open new opportunities for in‐inexpensive and highly efficient electro‐oxidation of ethanol for energy applications.     

A new simple preparation of platinum-nickel alloy nanoparticles and their characterization as an electrocatalyst for methanol oxidation

Pt-Ni alloy nanoparticles were produced by casting 2 or 10 mM H₂PtCl₆ solutions on a Ni column. The apparent particle size for the resultant Pt-Ni alloys increased with the concentration of the H₂PtCl₆ solution, while the content of Pt in the alloy decreased. The potential sweeps of 5 cycles in an H₂SO₄ aqueous solution for Pt-Ni (2 mM)/Ni and Pt-Ni (10 mM)/Ni electrodes led to electrochemical behavior similar to a polycrystalline Pt electrode, suggesting the formation of a few thin Pt layers on each Pt-Ni alloy surface. In electrochemical measurements, both Pt-Ni/Ni electrodes showed more negative onset potential of methanol oxidation and slower degradation of oxidation current of methanol than the polycrystalline Pt electrode. X-ray photoelectron spectroscopy of both Pt-Ni/Ni electrodes showed the shift of Pt4f peaks to a higher binding energy, suggesting that the increase in the d vacancy in the balance band 5d orbital of Pt contributed to the improved electrocatalytic activity and durability of the Pt-Ni/Ni electrodes.     

Preparation and electrochemistry of Pd-Ni/Si nanowire nanocomposite catalytic anode for direct ethanol fuel cell

A new silicon-based anode suitable for direct ethanol fuel cells (DEFCs) is described. Pd-Ni nanoparticles are coated on Si nanowires (SiNWs) by electroless co-plating to form the catalytic materials. The electrocatalytic properties of the SiNWs and ethanol oxidation on the Pd-Ni catalyst (Pd-Ni/SiNWs) are investigated electrochemically. The effects of temperature and working potential limit in the anodic direction on ethanol oxidation are studied by cyclic voltammetry. The Pd-Ni/SiNWs electrode exhibits higher electrocatalytic activity and better long-term stability in an alkaline solution. It also yields a larger current density and negative onset potential thus boding well for its application to fuel cells.     

脉冲电沉积Pd-Ni合金纳米颗粒及其甲酸电催化氧化

采用方波脉冲方法,在钯镍合金电解液中成功地电化学沉积出镍原子含量分别为12.0%、16.4%和22.6%的钯镍合金纳米颗粒. 钯镍合金纳米颗粒为球状,粒径50 ~ 80 nm. 随钯镍合金生长电位负移,合金的镍含量提高,其纳米颗粒大小基本相似但纳米颗粒数目增多,交联度提高和真实活性面积增大. 钯镍合金纳米颗粒镍含量提高,在硫酸溶液中其氢弱吸附峰电流增大. 钯镍合金纳米颗粒电极的甲酸电催化氧化活性较好,随合金纳米颗粒的镍含量提高和交联度增加,合金纳米颗粒电极的甲酸电催化氧化稳定性更高.     

Nickel foam-based composite electrodes for electrooxidation of methanol

Nickel foam and five nickel foam-based composite electrodes were prepared for being used as anode materials for the electrooxidation of methanol in KOH solution containing 0.1 and 1.0 M of methanol. The layered electrodes composed of nickel foam, platinum nanoparticles, polyaniline (PANI) and/or porous carbon (C) prepared in various assemblies. As shown by SEM analysis, depending on the preparation conditions, the electrodes of different morphologies were obtained. Using the cyclic voltammetry method, the oxidation of methanol on nickel foam electrode was observed in the potential range 0.4 V ↔ 0.7 V, where the Ni(OH)₂/NiOOH transformation occurred. The presence of Pt particles in electrode gave rise to the increase in electrocatalytic activity in this potential range. For electrodes containing dispersed platinum catalyst (Ni/Pt, Ni/PANI/Pt and Ni/C/Pt), the oxidation of methanol was noted also in the potential range −0.5 V ↔ 0.1 V. The electrocatalytic activities of the examined electrodes toward methanol oxidation at low potentials were in order Ni/Pt > Ni/C/Pt > Ni/PANI/Pt, whereas at high potentials in order Ni/PANI/Pt > Ni/Pt> Ni/C/Pt > Ni. Among the examined electrodes, the most resistant to cyclic poisoning appeared to be the Ni/C/Pt electrode. Presented at the 4Th Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005     

PtNiSnO_2/C的制备、表征及其电催化氧化乙醇活性

采用改进的B?nnemann法成功制备了Pt/C、Pt-Ni_(1/3)/C、Pt-SnO_2/C、Pt-Ni_x-SnO_2/C(x=1/4,1/3,2/3,1)阳极电催化剂。利用X射线衍射(XRD)、高分辨透射电子显微镜(HR-TEM)以及X射线光电子能谱(XPS)对催化剂晶型结构、表面形貌和表面电子结构进行了表征。运用线性扫描伏安(LSV)和电流密度-时间(j-t)曲线进行电化学测试,研究了乙醇电催化氧化(EOR)活性。并用原位红外光谱(in situ FT-IR)研究了EOR过程中产物的分布。结果表明,Pt-Ni_(1/3)-SnO_2/C是由Pt-Ni合金和SnO_2两相组成。XPS结果表明,在Pt-SnO_2中添加微量的Ni,Pt表面电子结构发生了改变。电化学结果表明,三元催化剂的EOR活性均优于二元和纯Pt,其中Pt-Ni_(1/3)-SnO_2/C的EOR活性最佳。Ni和SnO_2的加入并没有显著提高乙醇C―C键的断裂能力,但是二者的协同作用在低电位(0.1 V)下加强了乙醛的进一步氧化,生成了乙酸。     

电化学阶边精饰法制备钯镍合金纳米线的研究

运用连续恒电势三脉冲的电化学阶边精饰法在高定向石墨(HOPG)上制备钯镍合金纳米线阵列， 并研究了合金成分的影响因素. 结果表明，改变镀液组成可以调整钯镍合金成分，调整生长时间和生长电势来控制钯镍合金纳米线的直径. 用7 mmol•L^-1 PdCl2,3 mmo•L^-1 NiSO₄, 0.2 mol•L^-1 NH₄Cl，pH 8.5的混合溶液，控制脉冲电势-2.0 V形核0.2 s，在脉冲电势－0.4 V生长1 h，可以获得平均直径为200 nm, 长度约400 μm的钯镍合金纳米线阵列, 纳米线的合金成分中镍含量为12.4%(质量分数,w).     

Graphene aerogel supported Pt-Ni alloy as efficient electrocatalysts for alcohol fuel oxidation

Alcohol fuels oxidation plays a significant role in carbon sustainable cycling and high-performance catalyst with a strong anti-poisoning effect is desired. Herein, Pt-Ni alloy supported on the N-doped graphene aerogel synthesized by simple freeze-drying and annealing was demonstrated to have such catalytic ability for alcohol fuel oxidation. Pt-Ni alloy particles were found uniformly dispersed over the surface of 3D N-doped graphene aerogel. High anti-poisoning ability for CO-like intermediates...