纳米纤维素/碳纳米管/纳米银线柔性电极的制备

目的以竹粉为原料制备纳米纤维素,并将其作为基底材料制备纳米纤维素/碳纳米管/纳米银线复合电极,应用于柔性超级电容器。方法采用化学机械处理法,将竹粉通过化学处理以及研磨、超声等处理,制备成纳米纤维素悬浮液;分别将多壁碳纳米管和纳米银线超声分散于溶剂中;最后,通过层层自组装制备纳米纤维素/碳纳米管/纳米银线复合电极,同时,作为对照组,制备纳米纤维素/碳纳米管复合电极。结果纳米纤维素纤丝的直径大约为30~100 nm,相互之间缠绕成网状结构,是很好的支撑材料,纳米纤维素/碳纳米管/纳米银线复合电极具有很好的成膜性和电化学性能,在扫描速率为30 m V/s时,面积比电容达到77.95 m F/cm~2。结论以纳米纤维素为基底,通过层层自组装方法制备的纳米纤维素/碳纳米管/纳米银线复合电极具有较好的电化学性能,可作为柔性超级电容器的电极。     

纳米铝粒子电极的脱/嵌锂离子特性

带直流电弧等离子体气相蒸发法制备球状Al纳米粒子,并对其进行了XRD、TEM以及电极的脱/嵌锂离子循环性能表征。结果表明,制备出的Al粒子大小约为100 nm,表面包覆一层厚度不到1nm的非晶氧化物。使用Al纳米粒子制做的负极极片组装电池,研究了电流密度对其电化学特性的影响。结果表明,电池的首次充放电曲线和前10次循环性能曲线表明,电流密度最小的Al电极首次放电容量最大,为951.9 mAh/g.首次容量损失也最大,其循环稳定性能也相应变差:而电流密度最大的Al电极首次放电容量为879.7mAh/g,其循环稳定性能最佳。首次放电结束后,在电极材料中出现了两种化合物AlLi和Al₂Li₃,与测试出的放电容量相符。     

硅油两步脱水法可控制备纳米二氧化钛透镜

利用纳米粒子由下而上的组装来制备具有亚波长特征结构的新材料已成为操控并利用光的重要手段。本研究报道了一种新的纳米组装技术——即硅油两步脱水法, 该方法利用油水界面的流变性和限制效应, 实现了可批量、高重复性地将15 nm的二氧化钛(TiO₂)纳米粒子组装成具有高折射率、高透明度的光学材料, 并对其组装过程及机理进行了详细的分析。此外, 该方法还可实现TiO₂纳米粒子与其他纳米材料, 如金(Au)纳米粒子、Au纳米棒、Au纳米立方块或氧化石墨烯之间均匀的复合, 制备出TiO₂/Au或TiO₂/氧化石墨烯复合材料。其中, TiO₂纳米粒子的复合可使Au纳米粒子、Au纳米棒或Au纳米立方块的表面等离子体吸收峰产生显著的红移, 表明该组装法为未来制备功能性复合光电器件提供了有效的途径。     

自组装时间和高温处理对Au/BDD电极表面形貌的影响及电化学性能分析

应用静电力自组装的方法在掺硼金刚石薄膜(BDD)电极表面制备了纳米Au颗粒的单层膜,通过高温加热使纳米Au颗粒牢固修饰在BDD薄膜表面。采用SEM和XPS对其表面形貌进行了表征,纳米Au颗粒在BDD薄膜表面分散均匀,且不存在团聚现象。采用循环伏安法和电化学阻抗谱对其电化学性能进行了研究,并对多巴胺进行了检测。结果表明:修饰后的BDD电极界面间电子转移速率显著提高,且对多巴胺表现出良好的电催化性;氧化峰电位由0.52V减小为0.3V,且氧化峰电流为BDD电极的1.9倍,检测限为3.0×10-6 mol/L,且在多巴胺和尿酸的混合溶液中有很强的选择性,为生物分子的检测提供了新方法。     

预掺杂法制备Au/TiO2纳米管薄膜及其光电性能研究

提出了一种在TiO_2纳米管(TNT)阵列形成之前将贵金属纳米粒子作为掺杂剂引入的预掺杂法,该方法可以有效地避免传统掺杂方法中贵金属粒子堵塞纳米管管口的问题。首先采用磁控溅射法在FTO导电玻璃基底上制备Au/Ti双层金属薄膜,然后将上层金属Ti膜进行电化学阳极氧化,退火后即可获得Au/TNT电极薄膜。利用扫描电子显微镜、X射线衍射和X射线光电子能谱分别对Au/TNT电极薄膜的微观结构和组成成分进行了观察和表征,确定Au元素存在于复合薄膜中的同时,还发现位于薄膜底部的Au纳米颗粒,经阳极氧化和退火后,扩散到了上层的TNT阵列薄膜中。测试发现,可见光照射下,Au/TNT电极薄膜的光电流密度和光催化降解率分别约为纯TNT阵列薄膜的2.0和1.3倍。因此,采用预掺杂法制备光电性能优良的Au/TNT电极薄膜是可行有效的。     

Au纳米粒子/双层TiO2周期结构的制备及其对乙醇的电催化性质

利用二次阳极氧化法成功制备了双层TiO₂纳米管周期结构。通过改变氧化电压可以有效地调整双层TiO₂纳米管的管径, 从而控制样品的形貌。通过实验优化确定双层TiO₂周期结构的制备条件为一次氧化电压60 V, 二次氧化电压40 V。利用原位光还原法, 在TiO₂周期结构表面负载了Au纳米粒子并研究了前驱体溶液浓度与光照时间对样品的影响。在0.05 mmol/L HAuCl₄溶液中光照90 min后得到的Au纳米粒子具有最优的形貌与分布。这种绿色的原位光还原法因为避免使用保护剂与还原剂而有效提高了Au纳米粒子的催化活性。制备所得的Au/TiO₂周期异质结构可以直接作为工作电极用于乙醇的电催化氧化, 并表现出了良好的催化活性与稳定性。除了Au纳米粒子, 其他金属纳米粒子如Ag、Pd、Cu等均可通过该方法成功负载于双层TiO₂纳米管周期结构上。这种新型的异质结纳米结构作为燃料电池的阳极材料表现出了巨大的潜力。     

纳米纤维素/碳纤维-聚苯胺/碳纳米管电极的制备

目的以纳米纤维素/碳纤维复合膜为导电基底,制备纳米纤维素/碳纤维-聚苯胺/碳纳米管超级电容器电极。方法利用超声处理和真空抽滤制备纳米纤维素/碳纤维复合膜;利用原位聚合法制备聚苯胺和聚苯胺/碳纳米管复合材料;通过真空抽滤法制备纳米纤维素/碳纤维-聚苯胺电极和纳米纤维素/碳纤维-聚苯胺/碳纳米管电极。结果在纳米纤维素/碳纤维复合膜中,碳纤维形成了互穿导电网络结构,是良好的超级电容器电极导电基体;纳米纤维素/碳纤维-聚苯胺/碳纳米管电极具有良好的电化学性能,在扫描速率为5 mV/s的条件下,质量比电容为380.74 F/g,且在1000次循环测试后,电容保留率为88.05%。结论以纳米纤维素/碳纤维导电复合膜作为基体制备的纳米纤维素/碳纤维-聚苯胺/碳纳米管电极具有良好的电化学性能,可以作为超级电容器电极。     

Au-Pt海胆状纳米结构的合成研究

采用油胺为还原剂和稳定剂,通过晶种生长法制备了Au-Pt海胆状纳米结构,研究了各种合成条件对产物结构及形貌的影响。结果表明,空气气氛下不能合成Au-Pt双金属杂聚体结构;Pt(acac)2和H2PtCl6·6H2O两种Pt前体对于产物形貌没有明显影响;强极性的1-十八烯参与合成反应时不易得到海胆状的双金属结构;不同Au/Pt配比对产物形貌影响的研究指出,Au-Pt海胆状杂聚体结构的形成是因为后还原的Pt会倾向性地沉积到先还原成核的Au纳米颗粒的特定表面。一锅法合成得到了AuPt合金结构,表明后还原的Pt以Au为晶种,在小尺寸效应作用下使颗粒发生纳米尺度的原子扩散形成了带浓度梯度的AuPt合金。     

Au修饰SnO2复合纳米材料的制备和气敏性能

以氯金酸和乙酰丙酮氯化锡为主要材料,通过一步水热法制备了SnO₂和Au修饰的SnO₂（Au/SnO₂）纳米粒子.使用TEM、EDS、XRD和XPS等手段对样品的形貌、组成及结构进行表征,研究了两种材料对乙醇的气敏性能.结果表明,两种纳米颗粒的尺寸都比较均一,平均直径约为9-12 nm;SnO₂为四方金红石结构,Au为面心立方结构;在Au/SnO₂样品中,Au与SnO₂的重量比为2.6%,Au元素主要以Au⁰的价态存在并含有少量的Au³⁺价态;与纯SnO₂纳米粒子相比,Au修饰可显著提高气敏元件对乙醇响应的灵敏度和选择性。     

石墨烯支持Pt纳米粒子修饰电极的制备及电催化活性研究

采用一步电化学法制备了石墨烯支持Pt纳米粒子修饰电极(Nano-Pt/ERGO/GCE),利用交流阻抗研究了电极的性能以及该修饰电极的电催化活性。结果表明,采用循环伏安法制备石墨烯支持Pt纳米粒子,具有制备方法简单且纳米粒子粒径可控等优点。与单独的Pt纳米粒子修饰电极相比,Nano-Pt/ERGO/GCE电极表面Pt粒子分布更均匀,对甲醇的氧化具有极强的电催化活性。研究成果在甲醇燃料电池的研发中具有潜在的应用价值。     

Au-Pt纳米颗粒/石墨烯-纤维素微纤维复合电极的制备与电化学性能

石墨烯和金属纳米是优异的导电纳米材料,为构建具有高效活性表面积的电化学传感界面,以玻碳电极作为导电基底,采用滴涂法结合一步电沉积成功制备了Au-Pt纳米颗粒/还原氧化石墨烯-纤维素微纤维(Au-Pt NPs/RGO-CMF)复合材料。SEM、原子力显微镜(AFM)、EDS和拉曼光谱分析表明,Au-Pt纳米颗粒均匀分布在RGO-CMF的薄层上,同时实现了氧化石墨烯(GO)还原为RGO。以铁氰化钾作为氧化还原探针对界面的电化学性质进行研究,在优化的实验条件下(循环伏安法电沉积:电位为?1.2~0 V,周期为20,电解质pH值为6,滴涂GO-CMF体积为8 μL),得到Au-Pt NPs/RGO-CMF复合材料的高效活性表面积(3.54 cm2)远远优于裸玻碳电极(1.52 cm2)。表明构建界面具有高的电催化活性,为传感器的进一步应用提供理论支持。      

Immobilization of Prussian Blue nanoparticles onto thiol SAM modified Au electrodes for electroanalytical or biosensor applications

Poly(vinylpyrrolidone) (PVP)-protected Prussian Blue (PB) nanoparticles were prepared by simply mixing FeCI3 and K4Fe(CN)6 with absence or presence of HCI or/and KCI in water solution. The obtained PB nanoparticles were immobilized onto thiol self-assembled monolayer (SAM) modified Au electrodes. L-cysteine (Cys) and 1,8-octanedithiol (ODT) were compared as a bridge between the gold surface and the PB nanoparticles. The results show that PB prepared from the initial solution with KCI gives preferred electrochemical response and that Cys/Au shows improved immobilization effect of PB than ODT/Au. The obtained PB/Cys/Au electrodes exhibit electrocatalytic activity toward H2O2 reduction and DL-homocysteine (HCys) oxidation. Glucose oxidase (GOX) was immobilized onto PB modified electrode to explore the potentials for the design of oxidase-based biosensors. It is possible to anchor PB nanoparticles and develop their application on electroanalysis and biosensing.     

Investigation of space charge at pentacene/Au interface with UV/ozone treatment by a near-field microwave microprobe

The near-field microwave microprobe (NFMM) and Kelvin-probe measurements were performed to evaluate the conductivity in terms of surface potential of pentacene films on Au electrode. The UV/ozone treated and untreated Au electrodes were prepared to reveal the relationship between the electrical conductivity and interfacial electrostatic charging phenomena. For the pentacene film deposited on the Au electrode with UV/ozone treatment, holes were displaced from Au electrode to pentacene film, resulting the accumulation of apparent positive charges in the interfacial region of pentacene film around Au electrode. The NFMM measurement revealed that the reflection coefficient of microwave, S₁₁ increased with UV/ozone treatment, indicating the resistance decrease of the surface. Accumulation of positive charge in the interfacial region of Au electrode/pentacene film is one of the essential reasons for the increase of the conductivity of pentacene film.     

Superoxide dismutase-based third-generation biosensor for superoxide anion

A third-generation biosensor for superoxide anion (O2-) was developed by immobilizing superoxide dismutase (SOD) on a self-assembled monolayer of cysteine on gold electrode; i.e., a SOD/cysteine-modified gold electrode (SOD/Cys/Au) was fabricated. A rapid and direct electron transfer of SOD was realized at the gold electrode by using the cysteine molecule as an electron-transfer promoter. The promoted direct electron transfer of SOD and biomolecular recognition by the exploitation of specific and significant enzyme-substrate reactivity of SOD toward O2- combined with the low operating potential enabled a sensitive measurement of O2-. At SOD/Cys/Au, O2- could be specifically oxidized and reduced to O2 and hydrogen peroxide, respectively, through the inherent catalytic reaction of SOD. This allowed us to measure O2- by polarizing the electrode both anodically and cathodically. We could successfully measure O2- by suitably polarizing the electrode, typically at 300 and -200 mV versus Ag/AgCl without the virtual interference from physiological levels of H2O2, ascorbic acid, uric acid, and metabolites of neurotransmitters. The response mechanism of SOD/Cys/Au to O2- and its sensor characteristics are also presented and discussed.     

Preparation and catalytic activity of Au-Pd, Au-Pt, and Pt-Pd binary metal dendrimer nanocomposites

Catalytic activity of Au-Pt, Au-Pd, and Pt-Pd dendrimer nanocomposites for reduction of p-nitrophenol was investigated in water. The bimetallic dendrimer nanocomposites were prepared by simultaneous reduction with sodium borohydride in the presence of poly(amidoamine) (PAMAM) dendrimers with amine and carboxyl terminal groups. Average diameters of the obtained particles were 2-4 nm by transmission electron microscopy. From UV-vis spectroscopy, it was found that the particles were not mixtures of monometallic particles but binary ones. X-ray photoelectron spectroscopy showed that formation of binary composite particles prevents palladium atoms from oxidation. The Au-Pd and Pt-Pd binary particles exhibited higher catalytic activity than monometallic ones. On the other hand, catalytic activity of Au-Pt binary particle was comparable to that of platinum nanoparticles.     

Simple and convenient preparation of Au-Pt core-shell nanoparticles on surface via a seed growth method

Au-Pt core-shell nanoparticles were prepared on glass surface by a seed growth method. Gold nanoparticles were used as seeds and ascorbic acid-H₂PtCl₆ solutions as growth solutions to deposit Pt shell on the surface of gold nanoparticles. These core-shell nanoparticles and their growth process were examined by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and field-emission environmental scanning electron microscopy and the results indicated that the deposition speed was fast and nanoparticles with obvious core-shell structure could be obtained after 2 min. Moreover, this seed growth method for preparation of the core-shell nanoparticles is simple and convenient compared with other seed growth methods with NH₄OH as a mild reductant. In addition, electrochemical experiments indicated that these Au-Pt core-shell nanoparticles had similar electrochemical properties to those of the bulk Pt electrode.     

金/钯哑铃状纳米晶的制备及其催化对硝基苯酚还原研究

采用晶种-溶液生长法制备了单分散性良好、长径比均一的Au纳米棒, 利用H₂PdCl₄作为前驱体, CTAC作为软模版, 抗坏血酸作为还原剂对Au纳米棒进行改性合成了金/钯哑铃状结构纳米晶(Au/Pd NDs)。采用透射电子显微镜(TEM)、X射线能谱仪(EDS)和紫外-可见分光光度计(UV-Vis-NIR)对样品的结构和形貌进行表征, 探讨了铃铛状结构形成的机理, 并研究了其对硼氢化钠还原对硝基苯酚反应的催化性能。结果表明: 大量的多晶钯颗粒定向选择生长在金纳米棒(AuNRs)两端, 形成哑铃状结构; 通过调控还原剂与前驱体的比例, 铃铛尺寸连续可调。当钯的分散性好且总的催化活性位点多时, 金/钯哑铃状结构纳米晶催化对硝基苯酚还原的效率高。钯颗粒尺寸为20.7 nm的Au/Pd NDs(0.04 mg/mL)催化对硝基苯酚还原的反应速率常数可达0.44 min^-1, 证明其是一种非常有效的催化剂。     

Au-CZT与Au/Cr-CZT接触性能比较

本文通过附着力测试,应力模拟和IV特性及多道能谱分析对Au-CZT与Au/Cr-CZT接触进行研究。结果表明采用Au/Cr复合电极可提高电极附着强度和热稳定性。在老化实验中,Au-CZT界面附着力下降了61.98%,而Au/Cr-CZT仅降低28%。Au/Cr电极器件的漏电流较低,241Am射线下能谱响应更佳。分析其原因可能是Au与CZT间的Cr层降低了接触层内的热应力,合金化过程促进了金-半界面的互扩散,使Au和CZT更易形成欧姆接触,综合考虑Au/Cr复合电极能获得比Au电极更理想的接触性能。     

A biomimetic phospholipid/alkanethiolate bilayer immobilizing uricase and an electron mediator on an Au electrode for amperometric determination of uric acid.

A biomimetic bilayer membrane immobilizing uricase (urate oxidase; EC 1.7.3.3) (UOx) and a redox agent of 1-methoxy-5-methylphenazinium (MMP) was fabricated on an Au electrode substrate with use of the Au substrate coated with a self-assembled monolayer of n-octanethiolate (OT/Au) and L-alpha-phosphatidylcholine beta-oleoyl-gamma-palmitoyl (PCOP). The preparation was carried out by successively immersing an Au electrode substrate in an ethanol solution of OT, an MMP aqueous solution, and a suspension of proteoliposome formed by PCOP containing UOx and MMP. The prepared electrode exhibited such fast steady amperometric responses to uric acid as to allow its determination within 20 s after injecting uric acid, indicating that UOx-catalyzed electrochemical oxidation of uric acid was accomplished with assistance of electron mediation by MMP between UOx and the Au substrate. An increase in the response currents with increasing concentration of uric acid was obtained in a concentration range of uric acid found in healthy human blood. Any interference in the current response that is caused by direct anodic oxidation of uric acid or ascorbic acid was not observed at the prepared sensor electrode because the densely packed bilayer effectively blocked the diffusion of these substrates toward the Au surface, making it possible to determine amperometrically uric acid at the electrode with high precision.