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.     

Au-Ni异质结纳米晶的尺寸调控

系统研究了贵金属引导还原法制备Au-Ni异质结纳米晶中的尺寸控制规律, 并通过TEM、紫外-可见光谱对样品进行了表征. 研究表明: 在240 ℃条件下, Au-Ni异质结的合成过程中, 减少Au前驱体用量, 并不能减小异质结中Au端颗粒的尺寸, 此时其尺寸保持不变而Ni端颗粒的尺寸明显增大; 在反应体系中引入适量的双十二烷基二甲基溴化铵(DDAB)会使异质结Au端颗粒尺寸相应减小, 同时Ni端颗粒尺寸保持不变, 进而实现异质结两端颗粒尺寸的选择性调控. 要实现Au、Ni端颗粒尺寸的同时减小需降低反应温度, 但一定范围内的升高温度则不会产生明显作用. 以上研究不单提供了纳米异质结的调控方法, 也为进一步研究Au-Ni双金属纳米晶的催化等性能打下了材料基础.     

尺寸可控、高热稳定性有序介孔碳Au催化剂的合成

纳米Au催化剂被认为是具有商业价值的用于醇选择氧化的第二代催化剂.这是因为Au氧化还原电势高,化学稳定性好,可抑制易使Pt族元素中毒的胺等的毒化;其次,对于一些特定选择氧化和还原反应而言,具有较优的反应选择性.目前较多的研究集中在调变Au纳米颗粒与氧化物载体的相互作用,获得协同效应.例如,利用CeO2纳米晶为载体,沉积Au纳米颗粒(约3 nm),使CeO2部分还原为非计量比的催化材料,活化氧并获得高选择氧化性能.碳是相对惰性的载体,与Au相互作用力弱,因此可被用于研究Au纳米颗粒本征催化性能.但负载碳金催化剂在焙烧甚至还原过程中易团聚,且在反应中易流失,可能导致活性下降.利用胶体沉积法可获得介孔碳担载纳米Au催化剂,对葡萄糖选择氧化具有很高的催化活性和选择性.但是,制备中使用的保护剂残留经常被忽略.由于立体效应或电子结构调变作用,保护剂可能影响Au催化剂活性或稳定性.我们前期建立了反应单体参与的自组装技术合成功能化介孔碳路线,一步在介孔碳骨架中掺杂氧化物纳米催化剂.本文从介孔催化材料的结构出发,设计“镶嵌”在碳骨架中的纳米Au颗粒.采用配位作用辅助表面活性剂自组装技术,以苯酚和甲醛为碳前体,引入含巯基硅烷偶联剂,通过配位作用稳定金离子,获得尺寸可控介孔碳限域纳米Au催化剂.低温炭化中,由于巯基-金的配位作用阻抑金属移动或团聚,高温下聚合物炭化为相对刚性的碳骨架.此时,Au纳米颗粒被相邻介孔孔墙限制.硅烷偶联剂可除去,不影响碳载体,并可产生丰富二级孔道,获得多级孔道介孔碳材料.X射线衍射和透射电镜结果显示,所合成的催化剂中Au颗粒的尺寸可控,为3-18nm,且具有单分散性,均匀地分散在整个介孔碳骨架中,其含量为1.1-9.0 wt％.金碳催化剂具有有序的二维六方介孔结构.能量散射谱(EDX)也证明了催化剂只含有C,O和Au元素,没有S和Si元素的残留.X射线光电子能谱(XPS)结果显示催化剂表面的Au含量远远低于ICP的测试结果,也证明了Au纳米颗粒分布在介孔碳骨架内,同时只含有C,O和Au元素也与EDX相符.X射线近边吸收谱结果表明,随着颗粒尺寸的减小,Au表面电子性质发生改变.N2吸脱附等温线显示,有序介孔碳金催化剂具有典型的第Ⅳ型曲线,说明孔径分布范围较窄,主孔道尺寸为3.4-5.7 nm.值得注意的是,低压力段吸附量显示明显突跃,暗示其具有一套约为2 nm的次级介孔.所有的催化剂都具有高的比表面积(1269-1743 m2/g)和大的孔体积(0.79-1.38 cm3/g).Au纳米颗粒具有高的热稳定性,在惰性气氛中,即使在600℃也未见明显聚集长大.进一步讨论了合成中影响金纳米颗粒尺寸的重要影响因素.(1)巯基含量:通过调节巯基组分的含量,可以调控催化剂中Au纳米颗粒的尺寸(9-18 nm).需要强调的是,Au纳米颗粒尺寸与巯基在新合成材料中的浓度有关,当巯基含量在所研究的范围中时(1.55-3.06 mmol/g),Au纳米颗粒尺寸仅仅与巯基浓度有关,而与Au浓度无关.(2)硫酸预炭化处理:新合成的材料经过一步硫酸预炭化处理,可以得到尺寸为3 nm的有序介孔碳金催化剂.表征结果证明,经过硫酸预碳化处理,大量表面活性剂被除去,同时聚合物载体发生部分碳化,有助于在后续高温炭化中保护3 nm金颗粒不团聚.尺寸可控、高热稳定性、无配体保护的有序介孔碳负载Au催化剂有望应用在催化和传感器等领域.     

尺寸可控、高热稳定性有序介孔碳Au催化剂的合成（英文）

纳米Au催化剂被认为是具有商业价值的用于醇选择氧化的第二代催化剂.这是因为Au氧化还原电势高,化学稳定性好,可抑制易使Pt族元素中毒的胺等的毒化;其次,对于一些特定选择氧化和还原反应而言,具有较优的反应选择性.目前较多的研究集中在调变Au纳米颗粒与氧化物载体的相互作用,获得协同效应.例如,利用CeO_2纳米晶为载体,沉积Au纳米颗粒(约3 nm),使CeO_2部分还原为非计量比的催化材料,活化氧并获得高选择氧化性能.碳是相对惰性的载体,与Au相互作用力弱,因此可被用于研究Au纳米颗粒本征催化性能.但负载碳金催化剂在焙烧甚至还原过程中易团聚,且在反应中易流失,可能导致活性下降.利用胶体沉积法可获得介孔碳担载纳米Au催化剂,对葡萄糖选择氧化具有很高的催化活性和选择性.但是,制备中使用的保护剂残留经常被忽略.由于立体效应或电子结构调变作用,保护剂可能影响Au催化剂活性或稳定性.我们前期建立了反应单体参与的自组装技术合成功能化介孔碳路线,一步在介孔碳骨架中掺杂氧化物纳米催化剂.本文从介孔催化材料的结构出发,设计"镶嵌"在碳骨架中的纳米Au颗粒.采用配位作用辅助表面活性剂自组装技术,以苯酚和甲醛为碳前体,引入含巯基硅烷偶联剂,通过配位作用稳定金离子,获得尺寸可控介孔碳限域纳米Au催化剂.低温炭化中,由于巯基-金的配位作用阻抑金属移动或团聚,高温下聚合物炭化为相对刚性的碳骨架.此时,Au纳米颗粒被相邻介孔孔墙限制.硅烷偶联剂可除去,不影响碳载体,并可产生丰富二级孔道,获得多级孔道介孔碳材料.X射线衍射和透射电镜结果显示,所合成的催化剂中Au颗粒的尺寸可控,为3-18nm,且具有单分散性,均匀地分散在整个介孔碳骨架中,其含量为1.1-9.0wt%.金碳催化剂具有有序的二维六方介孔结构.能量散射谱(EDX)也证明了催化剂只含有C,O和Au元素,没有S和Si元素的残留.X射线光电子能谱(XPS)结果显示催化剂表面的Au含量远远低于ICP的测试结果,也证明了Au纳米颗粒分布在介孔碳骨架内,同时只含有C,O和Au元素也与EDX相符.X射线近边吸收谱结果表明,随着颗粒尺寸的减小,Au表面电子性质发生改变,N_2吸脱附等温线显示,有序介孔碳金催化剂具有典型的第Ⅳ型曲线,说明孔径分布范围较窄,主孔道尺寸为3.4-5.7nm.值得注意的是,低压力段吸附量显示明显突跃,暗示其具有一套约为2 nm的次级介孔.所有的催化剂都具有高的比表面积(1269-1743m~2/g)和大的孔体积(0.79-1.38cm~3/g).Au纳米颗粒具有高的热稳定性,在惰性气氛中,即使在600℃也未见明显聚集长大.进一步讨论了合成中影响金纳米颗粒尺寸的重要影响因素.(1)巯基含量:通过调节巯基组分的含量,可以调控催化剂中Au纳米颗粒的尺寸(9-18nm).需要强调的是,Au纳米颗粒尺寸与巯基在新合成材料中的浓度有关,当巯基含量在所研究的范围中时(1.55-3.06mmol/g),Au纳米颗粒尺寸仅仅与巯基浓度有关,而与Au浓度无关.(2)硫酸预炭化处理:新合成的材料经过一步硫酸预炭化处理,可以得到尺寸为3 nm的有序介孔碳金催化剂.表征结果证明,经过硫酸预碳化处理,大量表面活性剂被除去,同时聚合物载体发生部分碳化,有助于在后续高温炭化中保护3nm金颗粒不团聚.尺寸可控、高热稳定性、无配体保护的有序介孔碳负载Au催化剂有望应用在催化和传感器等领域.     

载体对Au/BN催化剂苯甲醇选择性氧化性能的影响

本研究以三种不同结构特点的氮化硼(BN)充当载体,负载Au纳米颗粒进行苯甲醇选择性氧化反应,发现载体的结晶性、比表面积对活性相Au的尺寸具有显著影响.Au/BN500的比表面积是晶化程度高的Au/BN600、Au/BN700催化剂的四倍以上.相较于Au/BN700而言,Au/BN500催化剂Au纳米颗粒具有更好的分散性...     

Au/ZrO2催化CO氧化反应中ZrO2纳米粒子的尺寸效应

从同一ZrO(OH)2出发制备了三种不同尺寸的ZrO2纳米颗粒(ZrO2-CP：40-200nm,ZrO2-AN;18～25nm,ZrO2-AD：10～15nm),采用沉积-沉淀方法制备了相应的Au/ZrO2催化剂,用XRD,XRF,TEM和低温N2吸附对ZrO2和Au/ZrO2进行了表征．XRD和TEM分析表明Au/ZrO2样品中Au粒子的平均尺寸为4～5nm,而Zr02的晶相和颗粒大小没有因为“负载”Au粒子而发生变化．CO催化氧化反应的结果表明,Au／ZrO2催化活性随着ZrO2纳米粒子尺寸的减小活性明显增加．TEM／HRTEM结果表明,Au／ZrO2催化剂中Au粒子与ZrO2颗粒接触界面随ZrO2颗粒尺寸的减小而明显增加,这很可能是含有更小尺寸ZrO2纳米粒子的Au／ZrO2催化剂具有更高催化活性的重要原因。     

单个纳米颗粒的光散射检测技术进展

纳米颗粒因其在生物医学和生物分析领域具有重要的应用前景而备受关注.单个纳米颗粒的光散射检测技术是一种简单、有效地对纳米颗粒的尺寸、尺寸分布及浓度等进行表征的分析方法,尤其在揭露纳米颗粒的内在异质性方面具有独特优势.然而瑞利散射强度随粒径减小呈六次方衰减,使得小尺寸单个纳米颗粒的检测非常具有挑战性.本文对近年发展起来的多种单个纳米颗粒的光散射检测技术进行综述.     

二维g-C3N4表面Au粒子尺寸调节的界面电子传输行为及光催化性能

目前,环境污染与能源危机是直接影响着人类生存与发展的两大难题.以半导体材料作为催化剂、太阳能作为驱动力的光催化技术由于具有成本低廉、清洁环保、反应条件温和等优点被认为是解决上述问题最具开发价值的理想方法,并得到科研工作者的广泛研究与关注.近几十年的研究表明,该技术在有机污水处理及光催化还原CO2转化成高能燃料领域均有良好表现.本文采用高温热聚合及酸处理剥离技术,以尿素作为原料,成功制备出薄层二维g-C_3N_4(CN)纳米片材料,并以该材料作为载体及催化主体,通过恒温水浴还原技术在其表面负载不同尺寸的Au纳米粒子,成功制备出一系列Au/CN复合光催化材料.运用系统的表征及测试手段,对所制备的二维光催化材料的晶相结构、化学组分、形貌和表面特征及光电化学特性进行了详细表征与研究,并针对该二维材料表面Au纳米粒子的尺寸效应、表面效应和等离子体共振效应(LSPR)等特性研究了复合材料界面间电子的传输效率与迁移机制.尺寸较小的Au纳米粒子的费米能级到CN导带底端的距离较短,其表面原子比例及缺陷含量较高,有利于Au纳米粒子对光生电子的捕获并抑制电子空穴对的复合.由于LSPR效应,可见光下Au表面可产生大量高能热电子并注入到CN表面,从而抑制光生电子从CN导带到Au表面的传输.三维时域有限差分法(FDTD)模拟结果显示, Au纳米颗粒的尺寸越大,拥有的LSPR效应越强,其表面热电子含量越高,光电子传输抑制现象越强烈.光电化学性能分析(PEC)结果显示,在颗粒分布密度合理的情况下,具有较小尺寸Au纳米颗粒的复合材料内部光生电子空穴对的分离效率越高.光催化实验表明,在Au纳米粒子分布合理的情况下,拥有最小Au纳米颗粒尺寸的3-Au/CN样品表现出最好的光催化活性.在可见光条件下照射30 min,该样品对罗丹明B水溶液(RhB, 10 mg/L)的光降解效率高达92.66%;紫外光条件下照射8h,该样品光催化还原CO_2转化成CO和CH_4的产率分别为77.5和38.5μmol/g,约是纯CN还原性能的6倍和10倍.结合文献报道及上述实验结果,我们提出了一个尺寸影响的光催化作用机制.     

Au纳米标记物增强电化学免疫分析大肠杆菌的研究

通过在Au纳米颗粒表面修饰辣根过氧化酶(HRP)标记的大肠杆菌抗体制备了一种新型的Au纳米标记物, 并将该纳米标记物应用于增强电化学免疫分析大肠杆菌. 经过酶联免疫反应后, Au纳米标记物、免疫磁性颗粒(IMB)和大肠杆菌形成了IMB/抗体-大肠杆菌-Au纳米标记物的三明治式免疫复合物. 以3,3,5,5-四甲基联苯二胺(TMB)溶液作为底物, 采用电化学与流动注射检测(FIA)相结合的技术测定HRP的活性. 检测到的电流大小与免疫复合物上HRP的量成正比, 从而与大肠杆菌的浓度成正比. Au纳米颗粒增加了HRP的负载量, 增强了电化学信号, 大大提高了大肠杆菌的检测灵敏度. 实验结果表明, 大肠杆菌浓度在 1.0×102～5.0×104 cfu•mL－1范围内与电流大小成线性相关, 最低检测限达50 cfu•mL－1, 若对大肠杆菌样品溶液进行预浓缩, 将得到更宽的检测范围和更低的检测限. 本方法总的分析时间比其他方法短, 在1 h内就能完成对大肠杆菌样品的快速检测.     

三维石墨烯金属网固相萃取测定有机磷农药残留

以金属网为基体材料,通过化学键合的方式将氧化石墨烯和Au纳米颗粒层层组装到金属网表面,得到一种Au纳米颗粒改性的石墨烯气凝胶修饰的金属网萃取材料,并应用于有机磷农药的富集检测.与商用的萃取材料进行对比,相较于SAX、C18、-NH2、Carb、Florisil等材料,金纳米颗粒改性的三维石墨烯气凝胶金属网对有机磷农药分...     

铁氧化物/金磁性核壳纳米粒子的制备及其富集与SERS研究

本文用种子生长法制备铁氧化物/金磁性核壳纳米粒子, 并利用SERS对其磁场靶向性进行了检测.     

Controlling the structure and size of Au nanocrystals by annealing and ion sputtering

In situ thermal annealing was used for the first time to observe directly that Au nanoparticles, which were originally fully embedded in the near-surface region of TiO(2), can be tailored into hemispheres exposed at the surface at elevated temperature. Precise control of the size of the Au hemispheres was achieved by subsequent low-energy ion sputtering. This method can be used to control the structure and size of a wide variety of nanoparticles in a matrix where surface structure and particle size are required to obtain specific material properties.     

Size‐Controlled Synthesis of Highly Monodisperse Gold Nanoparticles without a Size‐Selection and Long Range Ordered 2‐D Arrangement

A simple method is used to control the size of cetyltrimethylammoniumbromide‐protected Au nanoparticles by a reversal micelle in safe organic solvent. These Au nanoparticles can be evolved to highly monodisperse Au nanoparticles capped 1‐dodecanthiol in the 2, 3, and 5 nm diameter by refluxing at～160°C for 7 hours. Their ultraviolet visible spectroscopy (UV‐vis), x‐ray diffraction (XRD, transmission electron microscopy (TEM) showed that all the three different size gold nanoparticles(NPs) displayed high size homogenous properties and easy formed large areas of long ordered two‐dimensional arrangement at the air/solid interface.     

金核银壳纳米粒子薄膜的制备及SERS活性研究

采用柠檬酸化学还原法制备金溶胶, 通过自组装技术在石英片表面制备金纳米粒子薄膜, 在银增强剂混合溶液中反应获得金核银壳纳米粒子薄膜. 用紫外-可见吸收光谱仪和原子力显微镜(AFM)研究了不同条件下制备的金核银壳纳米粒子薄膜的光谱特性和表面形貌, 并以结晶紫为探针分子测量了金核银壳纳米粒子薄膜的表面增强拉曼光谱(SERS). 结果表明, 金纳米粒子薄膜的分布、银增强剂反应时间的长短对金核银壳纳米粒子薄膜的形成均有重要影响. 制备过程中, 可以通过控制反应条件获得一定粒径的、具有良好表面增强拉曼散射活性的金核银壳纳米粒子薄膜.     

Modification of Escherichia coli single-stranded DNA binding protein with gold nanoparticles for electrochemical detection of DNA hybridization

The unique binding event between Escherichia coli single-stranded DNA binding protein (SSB) and single-stranded oligonucleotides conjugated to gold (Au) nanoparticles is utilized for the electrochemical detection of DNA hybridization. SSB was attached onto a self-assembled monolayer (SAM) of single-stranded oligonucleotide modified Au nanoparticle, and the resulting Au-tagged SSB was used as the hybridization label. Changes in the Au oxidation signal was monitored upon binding of Au tagged SSB to probe and hybrid on the electrode surface. The amplified oxidation signal of Au nanoparticles provided a detection limit of 2.17 pM target DNA, which can be applied to genetic diagnosis applications. This work presented here has important implications with regard to combining a biological binding event between a protein and DNA with a solid transducer and metal nanoparticles.     

An Electrochemical Sensor Based on Gold Nanoparticles Incorporated in Mesoporous MFI Zeolite for Determination of Purine Bases in DNA

An electrochemical sensor was developed based on gold nanoparticles incorporated in mesoporous MFI zeolite for the determination of purine bases. Au nanoparticles (AuNPs) were incorporated into the mesoporous MFI zeolite (AuNPs/m‐MFI) by post‐grafting reaction. The composite materials were characterized by transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and electrochemical methods. Au nanoparticles with a size of 5‐20 nm are uniformly dispersed in the pores of mesoporous MFI zeolite. And the morphology of MFI zeolite can be perfectly kept after pore expansion and Au nanoparticles incorporation. The electrocatalytic oxidation of purine bases (guanine and adenine in DNA) is investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The surface‐confined Au nanoparticles provide the good catalytic activity for oxidation of purine bases. The simultaneous detection of guanine and adenine can be achieved at AuNPs/m‐MFI composites modified glassy carbon electrode (GCE). The electrochemical sensor based on AuNPs/m‐MFI exhibits wide linear range of 0.5–500 μM and 0.8–500 μM with detection limit of 0.25 and 0.29 μM for guanine and adenine, respectively. Moreover, the electrochemical sensor is applied to evaluation of guanine and adenine in herring sperm DNA samples with satisfactory results.     

Facile synthesis of gold nanoparticles with narrow size distribution by using AuCl or AuBr as the precursor

Gold(I) halides, including AuCl and AuBr, were employed for the first time as precursors in the synthesis of Au nanoparticles. The synthesis was accomplished by dissolving Au(I) halides in chloroform in the presence of alkylamines, followed by decomposition at 60 degrees C. The relative low stability of the Au(I) halides and there derivatives eliminated the need for a reducing agent, which is usually required for Au(III)-based precursors to generate Au nanoparticles. Controlled growth of Au nanoparticles with a narrow size distribution was achieved when AuCl and oleylamine were used for the synthesis. FTIR and mass spectra revealed that a complex, [AuCl(oleylamine)], was formed through coordination between oleylamine and AuCl. Thermolysis of the complex in chloroform led to the formation of dioleylamine and Au nanoparticles. When oleylamine was replaced with octadecylamine, much larger nanoparticles were obtained due to the lower stability of [AuCl(octadecylamine)] complex relative to [AuCl(oleylamine)]. Au nanoparticles can also be prepared from AuBr through thermolysis of the [AuBr(oleylamine)] complex. Due to the oxidative etching effect caused by Br(-), the nanoparticles obtained from AuBr exhibited an aspect ratio of 1.28, in contrast to 1.0 for the particles made from AuCl. Compared to the existing methods for preparing Au nanoparticles through the reduction of Au(III) compounds, this new approach based on Au(I) halides offers great flexibility in terms of size control.     

Sonochemical synthesis of gold nanoparticles: effects of ultrasound frequency

The rate of sonochemical reduction of Au(III) to produce Au nanoparticles in aqueous solutions containing 1-propanol has been found to be strongly dependent upon the ultrasound frequency. The size and distribution of the Au nanoparticles produced can also be correlated with the rate of Au(III) reduction, which in turn is influenced by the applied frequency. Our results suggest that the rate of Au(III) reduction as well as the size distribution of Au particles are governed by the chemical effects of cavitation and are not significantly affected by the physical effects accompanying ultrasound-induced cavitation.     

Polyelectrolyte‐Functionalized Gold Nanoparticle Scaffold for the Sensing of Heparin and Protamine in Serum

We describe a shape‐controlled synthesis of polyelectrolyte‐functionalized flowerlike and polyhedral Au nanoparticles and the development of a nanoarchitectured platform for the selective and highly sensitive detection of protamine and heparin by voltammetric, impedimetric, and microgravimetric techniques. The functionalized Au nanoparticles were chemically synthesized in aqueous solution at room temperature in the presence of the polyelectrolyte (either protamine or heparin). The charge on the polyelectrolyte controlled the shape and surface morphology of the nanoparticles. The negatively charged heparin‐functionalized Au nanoparticles have multiple branched flowerlike shapes with an average size of 50 nm, whereas the cationic protamine‐functionalized nanoparticles are of polyhedral shape with an average size of 25 nm. Both flowerlike and polyhedral nanoparticles have (111), (200), (220), and (311) planes of a face‐centered cubic lattice of Au. Voltammetric, impedimetric, and microgravimetric sensing platforms based on functionalized Au nanoparticles have been developed for the sensing of heparin and protamine. The sensing platforms are developed by self‐assembling the functionalized nanoparticles on a thiol‐functionalized three‐dimensional silicate network. The microgravimetric sensing platform shows very high sensitivity and it can detect heparin and protamine at concentrations as low as 0.05 μg mL^?1. The selectivity of the sensing platform towards heparin was examined with potential interferents such as hyaluronic acid (HA) and chondroitin‐4‐sulfate (CS). Both HA and CS did not interfere with the measurement of heparin. The practical application of the sensing platform was demonstrated by measuring the concentration of heparin and protamine in human serum samples. The sensing platform could successfully quantify the concentration of heparin and protamine in the real serum samples with excellent recovery. The sensing platform was robust and could be used for repeated measurement without compromising the sensitivity.