Keggin 型磷钨酸盐修饰碳糊电极传感多巴胺的研究

多金属氧酸盐作为一类阴离子簇合物,由于其结构的多样性和尺寸大小的可调变性,在电化学、催化和药学等领域引起了人们的广泛关注.本文制备了多酸Co(C₁₅N₆H₁₂)₂[PW₁₂O₃₈]·5H₂O（Co[PW₁₂O₃₈]）修饰碳糊电极并通过电化学阻抗谱、循环伏安法以及差分脉冲伏安法对多巴胺的传感性能进行了研究.对其制备条件和检测条件分别进行了优化.在优化条件下,制备的传感器对多巴胺具有良好的选择性和灵敏度的检测能力.多巴胺的线性响应范围为8.0x10^-6 mol·L^-1至3x10^-5 mol·L^-1,灵敏度为0.039 μA·(μmol·L^-1)^-1,检出限（S/N=3）为5.4 x10^-6 mol·L^-1. 制备的多酸修饰碳糊电极用于检测多巴胺表现出良好的稳定性和重现性,并且对抗坏血酸、尿酸等常见的干扰物质,具有良好的抗干扰性. 多酸修饰的碳糊电极制备过程简单方便,成本低,传感性能良好,对应用于电化学传感器检测多巴胺具备潜在的应用前景.      

Potentiometric determination of hydrogen peroxide at MnO2-doped carbon paste electrode

A novel hydrogen peroxide (H₂O₂) potentiometric sensor, made with a MnO₂-doped carbon paste electrode (CPE), is reported. Under optimum conditions, the electrode gives a Nernstian response for H₂O₂ in the concentration range 3.00×10⁻⁷–3.63×10⁻⁴ mol/l, with a slope of 21–19.4 mV/pH₂O₂ and a detection limit of 1.2×10⁻⁷mol/l H₂O₂. In addition, this sensor offers some analytical characteristics such as sensitivity, good reproducibility and a simple preparation procedure. The effects of both the components of the electrode and other conditions on the potential response of the sensor, as well as the possible response mechanism, are discussed.     

Ti表面修饰纳米TiO2膜电极的电催化活性

用电化学合成法在Ti表面修饰一层纳米TiO₂膜,TEM和XRD测试表明晶型为锐钛矿型,晶粒平均尺寸为25nm.用循环伏安法、循环方波伏安法和电解合成法研究了纳米TiO₂膜电极在硫酸介质中的氧化还原行为以及对硝基苯还原的电催化活性。结果表明,纳米TiO₂膜电极具有异相氧化还原催化行为,膜中的Ti(Ⅳ)/Ti(Ⅲ)作为媒质间接电还原硝基苯为对氨基苯酚,收率和电流效率分别达91.6%和95.2%.     

Pt/DNA-MWCNTs/GC电极制备及其H2O2还原的电催化活性

将DNA功能化多壁碳纳米管（MWCNTs）复合材料修饰于玻碳基底（GC）表面制得DNA-MWCNTs/GC电极,并在此基础上电沉积负载Pt纳米颗粒构建了一种新型无酶H₂O₂传感电极. 利用扫描电子显微镜（SEM）表征制得的修饰电极,同时通过循环伏安法和计时电流法研究了该传感电极的H2O2响应性能. 结果表明,该传感电极的H₂O₂检测在0.04 ~ 18.07 mmol·L^-1浓度范围内成线性相关,检出限3.85 μmol·L^-1（S/N = 3）,且有良好的重现性、稳定性与选择性.     

基于Nafion固定磷钼酸和石墨烯共修饰PEDOT膜电极的电化学过氧化氢传感器

以玻碳电极（GCE）为基底电化学聚合制得聚3,4-乙烯二氧噻吩（PEDOT）膜修饰电极,再通过Nafion共固定磷钼酸和石墨烯构建了一种新型的无酶电化学H₂O₂传感器. 利用扫描电子显微镜（SEM）表征制得的修饰电极,并通过循环伏安法和计时电流法研究了传感器对H₂O₂的响应性能. 结果表明,在优化条件下,该传感器对H₂O₂还原具有良好的电催化性能,检测H₂O₂的线性范围为2.91×10^-6 ~ 1.83×10^-2 mol•L^-1,检出限和灵敏度分别为9.90×10^-7 mol•L^-1（S/N = 3）和112.5 μA•（mmol•L^-1）^-1. 此外,该传感器还具有良好的重现性和选择性.     

Immobilization of Hemoglobin on Cobalt Nanoparticles-modified Indium Tin Oxide Electrode:Direct Electrochemistry and Electrocatalytic Activity

A cobalt nanoparticles-attached indium tin oxide(CoNPs/ITO) electrode was applied to the immobilization of hemoglobin(Hb) and an Hb modified CoNPs/ITO electrode(Hb/CoNPs/ITO) was prepared. The direct electron transfer of Hb was shown by the well-behaved voltammetric responses for Hb/CoNPs/ITO electrode and the effects of scan rate and pH value were observed. Based on the catalytic activity of Hb immobilized on the CoNPs/ITO electrode toward the reduction of H₂O₂, a mediator-free H₂O₂ sensor was developed. A linear relationship existed between the catalytic current and the H₂O₂ concentration in a range of 1.0―100.0 μmol/L with a detection limit (S/N=3) of 0.2 μmol/L.     

"三明治夹心"型Ni-P@Ni-B/Ni电极的制备及高效全pH下的催化制氢性能

通过化学镀法制备了具有“三明治夹心”结构的Ni-P@Ni-B/Ni催化电极. 该催化材料为直径1 μm左右的微球. 电化学性能测试结果表明, 在电流密度为10 mA/cm ²时, 其在0.5 mol/L PBS缓冲液(pH=7)中的过电位仅为287 mV, 在此电位下连续工作24 h后, 电流密度仅衰减了7.6%. 同时Ni-P@Ni-B/Ni在酸性(0.5 mol/L H₂SO₄)和碱性(1 mol/L KOH)条件下也具有优异的析氢反应催化活性, 达到相同电流密度时过电位分别为199和79 mV. 该工作为全pH环境下高效电解水制氢提供了新思路.     

MOF derived Co3O4/N-doped carbon nanotubes hybrids as efficient catalysts for sensitive detection of H2O2 and glucose

Developing enzyme-free sensors with high sensitivity and selectivity for H2O2 and glucose is highly desirable for biological science.Especially,it is attractive to exploit noble-metal-free nanomaterials with large surface area and good conductivity as highly active and selective catalysts for molecular detection in enzyme-free sensors.Herein,we successfully fabricate hollow frameworks of Co3O4/N-doped carbon nanotubes(Co3O4/NCNTs)hybrids by the pyrolysis of metal-organic frameworks followed by calcination in the air.The as-prepared novel hollow Co3O4/NCNTs hybrids exhibit excellent electrochemical performance for H2O2 reduction in neutral solutions and glucose oxidation in alkaline solutions.As sensor electrode,the Co3O4/NCNTs show excellent non-enzymatic sensing ability towards H2O2 response with a sensitivity of 87.40μA(mmol/L)^-1 cm^-2,a linear range of 5.00μmol/L-11.00 mmol/L,and a detection limitation of 1μmol/L in H2O2 detection,and a good glucose detection performance with 5μmol/L.These excellent electrochemical performances endow the hollow Co3O4/NCNTs as promising alternative to enzymes in the biological applications.     

Preparation and Electrochemical Behaviors of AA-PEGMA Copolymer Film Electrode

A new kind of comblike copolymer film composed of acrylic acid-polyethylene glycol monomethyl ether acrylate copolymer(AA-PEGMA copolymer) was successfully synthesized to immobilize hemoglobin(Hb). FTIR, UV-Vis and CD spectra suggest that Hb kept its original structure in the AA-PEGMA copolymer film without denaturation. A pair of well-defined, quasi-reversible cyclic voltammetric peaks at around –270 mV vs. saturated calomel electrode(SCE) for the Hb Fe(Ⅲ)/Fe(Ⅱ) redox couple was observed on the film-modified electrode in phosphate buffer solution(PBS, pH=7.0). The formal potential of Hb/AA-PEGMA copolymer film-modified electrode is linearly dependent on solution pH with a slope of –46.3 mV/pH, illustrating that one-proton transfer was accompanied with each electron transfer. Furthermore, the modified electrode displayed electrocatalytic response to the reduction of H₂O₂ with a linear range of 3.5―126 μmol/L and a detection limit of 1.17 μmol/L. In conclusion, the AA-PEGMA copolymer film was proved to be an excellent matrix for the immobilization and electrochemistry of proteins.     

Multi-functional Photoelectric Sensor Based on a Three-fold Interpenetrated Cd(II) Coordination Polymer for Sensitively Detecting Different Ions

Athree-fold interpenetrated cadmium coordination polymer[Cd₃(BTC)₂(H₂O)₉]·2H₂O(CP 1)(H₃BTC=1,3,5-benzenetricar-boxylic acid) was selected and synthesized to investigate its photoelectric properties. CP 1 showed excellent sensitivity for Cr₂O₇^2- and Fe³⁺, low limit of detection(LOD:0.39 µmol/L for Cr₂O₇^2- and 1.72 µmol/L for Fe³⁺) and stability as electrochemical sensor. More importantly, fluorescence sensing studies indicated that CP 1 exhibits sensing activity for Fe³⁺, Fe²⁺, and MnO₄^- with good cyclic stability and selectivity. Low LOD and high-sensitivity capability of CP 1 make it a potential multifunctional photoelectric sensor.     

钴原卟啉附修饰玻碳电极为基底的胆固醇酶电极

本文利用钴原卟啉对H₂O₂氧化有很高催化活性的特点,以钴原卟啉修饰玻碳电极为基底,戊二醛交联法固定胆固醇氧化酶,以电聚合邻苯二胺膜抗干扰、抗毒化.得到了线性范围为0.1～2mmol/L,响应时间在30s以内,可连续使用150次的胆固醇酶电极.     

磁性印迹纳米粒子固定血红蛋白修饰磁性电极构建过氧化氢传感器

采用表面印迹技术,以磁性二氧化硅纳米粒子（Fe₃O₄@SiO₂ NPs）作为载体、血红蛋白（Hb）为模板分子、正硅酸乙酯（TEOS）为印迹聚合物单体,制备了Hb印迹Fe₃O₄@SiO₂的磁性印迹纳米粒子（MMIPs NPs）. MMIPs NPs具有磁性内核和血红蛋白印迹壳层的核壳结构,可以富集并固定Hb. 使用壳聚糖将MMIPs NPs固定于磁性电极表面,构建血红蛋白类酶生物传感器,研究了Hb对过氧化氢（H₂O₂）的催化活性. MMIPS NPS相比于磁性非印迹纳米粒子（MNIPS NPS）,催化电流增加了14.3%. 采用磁性电极,MMIPS NPS、Hb和O₂的顺磁性使得该类酶生物传感器对H₂O₂的催化电流增加了60.0%. 血红蛋白类酶生物传感器电流响应与H₂O₂浓度在25 ~ 200 μmol·L^-1间呈线性关系,检出限为3 μmol·L^-1（S/N=3）,表明该类酶传感器对H₂O₂具有良好的催化性能.     

铂微粒修饰的氧化钛电极对甲醇的电催化氧化性能

直接甲醇质子交换膜燃料电池(DMPEMFC)可用作未来电动车辆的动力电源,但要达到实际应用还有大量问题有待进一步解决.目前限制DMPEMFC实际应用的主要问题是甲醇阳极氧化催化剂低的活性、高的价格及催化剂的毒化.     

甘氨酸修饰的Pt(111)电极上的氧还原

利用单晶旋转圆盘电极技术（Hanging Meniscus Rotating Disk Electrode,　HMRD）在硫酸和高氯酸溶液中分别研究了甘氨酸修饰的Pt(111)电极表面氧分子的电催化还原反应. 实验发现：在硫酸溶液中,经甘氨酸修饰的Pt(111)电极表面的氧还原活性明显提高,其中氧还原的半波电位与Pt(111)电极的相比正移约0.1 V,而在高氯酸溶液中,甘氨酸修饰的Pt(111)电极的活性几乎没有发生变化. 该实验结果表明：甘氨酸修饰的Pt(111)电极一方面抑制了SO₄^2-在电极表面的吸附,另一方面又能在电极表面提供相邻的空位供氧分子吸附. 通过与文献中报道的CN^-修饰的Pt(111)电极上的氧还原结果的对比,可以推测甘氨酸修饰的Pt(111)电极表面氧还原活性提高是由于甘氨酸在Pt(111)表面可能先被氧化成CN^-后吸附在电极表面,进而促进了氧分子的电催化还原反应.     

基于对羟基苯硼酸为前驱体的金纳米粒子修饰电极电化学检测过氧化氢

以对羟基苯硼酸为前驱体,利用H₂O₂可以定量氧化对羟基苯硼酸产生对羟基苯酚的原理,以反应产物对羟基苯酚为电化学信号物质,结合金纳米粒子修饰玻碳电极（AuNPs/GCE）,发展了一种间接检测H₂O₂的电化学方法. 由于AuNPs/GCE具有有效电子传递性能和比表面积大等优点,对硼酸氧化产物具有较高的催化活性,因此在含1.0 mmol•L^-1对羟基苯硼酸的0.1mol•L^-1 pH 7.5 PBS中,AuNPs/GCE可以检测到1.0 ~ 1.0 × 10³ μmol•L^-1的H₂O₂,检测限为0.5μmol•L^-1. 同时,该方法具有良好的选择性和重现性,且操作简单、速度快、价格低廉,非常适用于实际样品中H₂O₂含量的测定.     

Au/L-Met/GC电极的H2O2电催化氧化

在无额外的添加剂和保护剂的情况下,以柠檬酸钠还原氯金酸制得链状金纳米粒子,使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察样品. 层层自组装技术可将金纳米粒子自组装,并分别以L-甲硫氨酸（L-Methionine,L-Met）、硫脲（Thiourea,TU）、丙烯基硫脲（Allyl thiourea,ATU）和聚乙烯吡咯烷酮（Polyvinylpyrrolidone,PVP）交联剂自组装于玻碳基底,即得金纳米粒子修饰电极. 以[Fe(CN)₆]^3-/4-氧化还原电对为探针,考察该修饰电极的电化学性质. Au/L-Met/GC电极有最佳电化学性能,循环伏安曲线和计时电流曲线测试表明,Au/L-Met/GC电极的H₂O₂电催化氧化有较高的灵敏度,线性范围2×10^-7 ~ 3×10^-3 mol·L^-1,检出限6.67×10^-8 mol·L^-1.     

高温质子交换膜燃料电池的复合催化层电极

高温质子交换膜燃料电池具有耐毒化,稳定性好的优势,是具有较强应用前景的一种能源转换装置。 本文制备了具有复合催化层结构的气体扩散电极,用于增强燃料电池阳极的催化性能。 在气体扩散电极中,将偏氟乙烯-六氟丙烯共聚物和聚苯基咪唑聚合物作为催化剂的粘结材料,调节了电极界面的浸润结构。 通过对电极表面形貌和润湿性的表征,发现该种结构的催化层孔隙率和粗糙度更高,双层结构的润湿性差别明显(接触角分别为149°和19°),这有利于形成稳定的三相反应界面。 测试结果表明,该种结构的催化层能够有效提高催化材料的利用效率,燃料电池对氢气燃料的峰值功率密度提高约22%。 与此同时,使用含一氧化碳质量浓度为10000和30000 mg/m³的氢气燃料,电池峰值功率密度能够分别保持82.1%和71.4%,证明该燃料电池对一氧化碳杂质保持了良好的耐毒性。     

Microwave-assisted One-pot Synthesis of Ag NPs/C and Its Application in H2O2 and Glucose Detection

The facile preparation of Ag NPs/C via a one-pot strategy was carried out by microwave treatment of a mixed aqueous solution of AgNO₃ and glucose at 180℃ for 20 min without the presence of extra reducing agent. The as-synthesized Ag NPs/C showed high catalytic performance toward the reduction of H₂O₂. The H₂O₂ sensor constructed with as-synthesized Ag NPs/C exhibited a short amperometric response time of less than 2 s. The linear range was approximately (0.1-50) mmol/L(r=0.997), and the detection limit was approximately 3.3 μmol/L at a signal-to-noise ratio of 3. A glucose biosensor was fabricated by immobilizing glucose oxidase onto Ag NPs/C- modified glassy carbon electrode to detect glucose. The glucose sensor had a wide linear response range of 2-22 mmol/L(r=0.999) and a detection limit of 190 μmol/L.     

New All-solid-state Carbonate Ion-selective Electrode with Ag2CO3-BaCO3 as Sensitive Films

A new all-solid-state carbonate ion-selective electrode was fabricated via electrochemical and ion-exchange reactions with Ag nanoparticles and Ag₂CO₃-BaCO₃ as ion-to-electron transducer and ion-selective layer, respectively. This paper presented the detailed procedures of the construction of the electrode, the applications of the electrode in various experiments, and the corresponding chemical reaction principles involved. The fabricated electrode was characterized by means of scanning electron microscopy(SEM), energy dispersive spectrometer(EDS), and electrochemical analyses. The electrode exhibited stable linear responses to carbonate anions(10^-5-10^-1 mol/L) with average slope of the curve being -26.56 mV per decade, and showed negligible responses to NO₃^- , SO₄^2-, and Sal^- anions. The electrode was further used to measure the concentration of carbonate anions in boiler water. The measured concentration was lower than that determined via titration. Overall, the electrode exhibited the advantages of miniaturized size, robust construction, and compatibility with other equipment and thus could be ideally integrated into various sensor platforms to collect chemical data from industrial heat exchangers.     

The Electrode Behavior and the Storing Capacity from Liver Ferritin of Dasynatis Akajei

Ferritin, a metallic protein, is a special biological large molecule that plays two central physiological functions in living cell simultaneously^[1]. In addition, the ferritin is able to express two functions having activity of H₂-uptake and exhibiting electrode behavior that picks the electrons up from a bare platinum electrode directly under anaerobic condition^[2-3]. In this paper, a direct electrochemical technology under aerobic conditions is employed to study kinetics of iron release from liver ferritin of Dasyatis akajei (DALF). Using aerobic condition, an electron tunnel across the ferritin shell plays still a critical role in taking the electrons from a bare platinum electrode for iron release without any mediator aid. Moreover, using similar condition, two reduction potentials of the ferritin core with -135 mV and -416 mV vs. NHE are measured by the technology. Unlike other processes of iron release, a kinetic study for complete iron release is confirmed to show a triphasic behavior defined as zero-order reaction. DALF is known to heme bind to generate a hemeoprotein, named DALF_h The heme function has been investigated to accelerate rate of iron release. Using similar studies, the kinetic datum indicates that the rate of iron release depends tightly on not only the reduction potential of the electrode, but also the regulation capacity of protein shell itself.