十二烷基苯磺酸掺杂聚吡咯在阳极-阴极交替极化下的防污性能

采用化学氧化聚合法合成了一系列十二烷基苯磺酸掺杂的聚吡咯(PPy-DBSA), 并研究了其电化学防污性能. 循环伏安(CV)曲线表明, PPy-DBSA在天然海水中具有良好的电化学活性和稳定性. 采用循环伏安扫描方法实现阳极极化和阴极极化交替进行, 并对极化后的PPy-DBSA电极进行了抑菌性能研究, 发现PPy-DBSA在循环伏安阳极-阴极交替(-1.0~2.0 V vs. SCE)极化下, 可成功抑制微生物(大肠杆菌)的附着, 其中在-0.6~0.8 V范围内循环伏安阳极-阴极交替极化20 min时防污效果最佳, 抑菌率可达99.8%, 明显优于恒电位阳极极化和恒电位阴极极化的结果.     

电化学预处理玻碳电极示差脉冲伏安法测定水中痕量铅

将玻碳电极在pH 4.0乙酸盐缓冲溶液中,于电位+1.8 V(vs.SCE)处阳极氧化,然后在-0.8~+1.0 V电位范围内循环扫描,进行预处理。研究了铅离子在预处理玻碳电极上的电化学行为,结果表明:与未修饰的电极相比,Pb2+在该修饰电极上有一对氧化还原峰,峰电位分别为-0.57 V和-0.68 V(vs.SCE),且峰电流大大提高。据此提出了示差脉冲伏安法测定Pb2+的方法。在优化的试验条件下,氧化峰电流与Pb2+的浓度在3.2×10-7~4.2×10-5mol.L-1范围内呈线性关系。检出限(3S/N)为3.2×10-8mol.L-1。应用该预处理电极测定水样中微量铅,加标回收率在93.8%~104.7%之间,相对标准偏差(n=6)在3.1%~4.3%之间。     

聚乙撑二氧噻吩阳极降解的研究

研究了聚乙撑二氧噻吩(PEDOT)膜在水溶液中的阳极降解过程. 研究发现PEDOT的阳极过程可以分为p掺杂区[电位范围－0.3～0.5 V (相对于饱和甘汞电极; vs. SCE)]、过渡区[电位范围0.6～1 V (vs. SCE)]、过氧化区[电位范围1.2～1.6 V (vs. SCE)]三个电位区域. 用电化学阻抗谱法、循环伏安法、红外光谱技术、膜电阻测量以及电子自旋共振技术分别研究了PEDOT膜在这三个电位区域的行为. 结果表明: PEDOT膜在这三个电位区域的性质有明显不同. 在p掺杂区PEDOT膜的官能团、共轭结构、导电性均保持, 即在这个电位区发生可逆的掺杂/脱掺杂反应, 膜几乎不降解. 在过渡区和过氧化区, PEDOT膜均发生了降解. 与传统的导电聚合物在高电位的阳极降解的过氧化过程不同, 我们认为膜在较高电位(过渡区)发生一个驰豫过程, 该过程使得膜的官能团改变, 但是膜的共轭结构和导电性均保持; 而在更高的电位区(过氧化区)膜的降解和一般意义的过氧化降解相同, 此时膜的官能团、共轭结构、导电性均发生不可逆的破坏.     

铅锑合金在硫酸溶液中的阳极膜I.早期阳极膜生长动力学

本文用线性电位扫描法(20mV.s-1),自I.2V(vs.Hg/Hg2SO4)扫描至-1.2V,研究了三种铅锑合金在3.5MH2SO4溶液中(30℃),经一定时间(60,600,1200,)和240Os)1.2V阳极极化形成的阳极膜,该阳极膜的主要成分可能是PbO.PbSO4,其表面为PbO2.本文摊导出与实验一致的此种阳极膜的生长学方程式,并利用该式测得氧原子在阳极膜中的扩散系数。     

铅锑合金在硫酸溶液中的阳极膜——Ⅰ.早期阳极膜生长动力学

本文用线性电位扫描法(20 mV·s~(-1)),自1.2 V(vs.Hg/Hg_2SO_4)扫描至-1.2V,研究了三种铅锑合金在4.5 MH_2SO_4溶液中(30℃),经一定时间(60,600,1200,和2400s)1.2 V 阳极极化形成的阳极膜.该阳极膜的主要成分可能是 PbO·PbSO_4,其表面为 PbO_2.本文推导出与实验一致的此种阳极膜的生长动力学方程式,并利用该式测得氧原子在阳极膜中的扩散系数.     

中性介质中L-丝氨酸在Pt电极上解离吸附和氧化的原位FTIR研究

运用电化学循环伏安(CV)和原位红外反射光谱(in situ FTIRS)研究了中性介质中L-丝氨酸在Pt电极上的解离吸附和氧化过程. 结果表明, 在中性溶液中, 以两性离子形式存在的丝氨酸可以在很低的电位下(-0.6 V, vs. SCE)在Pt电极表面发生解离吸附, 生成强吸物种一氧化碳(COL)、(COB)和氰负离子(CN-). 研究结果还表明, 当电位低于0.7 V(vs. SCE)时, CN-能稳定存在于电极表面, 抑制丝氨酸的进一步反应. 在更高电位时则主要为丝氨酸分子的氧化过程.     

芦荟大黄素1.5阶微分阳极溶出伏安法测定及电化学性质研究

研究了芦荟大黄素在以 0 .1mol/LHAc (pH 2 .89)为支持电解质 ,玻碳电极为工作电极的吸附伏安行为 .结果表明芦荟大黄素存在一个准可逆的双电子转移过程 ,其峰电流Ip 和峰电位Ep 与溶液 pH值有关 .同时还建立了用 1.5阶微分阳极溶出伏安法测定含量的新方法 .在 - 0 .80V(vs.SCE)电位下富集 ,可得一灵敏的微分阳极溶出峰 ,峰电位Ep 为 - 0 .38V ,峰电流Ip 与芦荟大黄素的浓度在 2 .0× 10 - 7～ 8.0× 10 - 6 mol/L范围内成线性关系 ,最低检出限为 1.0× 10 - 7mol/L .该法用于含有芦荟大黄素体系的测定 ,具有简便、快速、准确等优点     

2-巯基苯并噻唑对铜缓蚀行为的表面增强红外光谱研究

2-巯基苯并噻唑(MBT)是Cu的高效缓蚀剂,但是缓蚀机理存在较大争议.本文通过电化学极化曲线从宏观角度对缓蚀效率进行评估,并利用原位衰减全反射-表面增强红外光谱技术结合理论计算研究了电位控制下的微观吸附构型.结果表明:在较高电位(大于0 V,相对饱和甘汞电极(SCE))下,MBT和金属Cu之间发生电子转移,MBT以硫醇式的环外S和N与金属Cu(I)离子配位在表面形成聚合物膜;在较低电位(小于0 V,vs SCE)下,MBT通过环外S原子以硫醇离子形式在金属Cu表面直立吸附.表面膜阻止了腐蚀介质的侵蚀,起到了较好的缓蚀效果.     

苯亚甲基丙二腈在汞阴极上的还原反应

本文应用了多种电化学方法(循环伏安法,微分脉冲极谱法等)及UV光谱,GC-MS手段研究了苯亚甲基丙二腈(BDMN)在汞阴极上的还原过程.在0.03mol.L^-1四乙基溴化铵(TEAB),50%二氧六环-水介质中BDMN还原的微分脉冲极谱图上有两个峰,第一个峰是此分子中的双键还原,生成苄基丙二腈引起的,峰电位在-0.98V(vs.SCE).第二个峰的峰电位在-1.55V(vs.SCE),此峰是BDMN的水解产物苯甲醛还原为苯甲醇产生的.BDMN的整个电极反应为ECEC过程.此处,对BDMN及二氧六环在汞电极上的吸附现象也进行了研究.     

三元络合物微分阳极溶出伏安法测定亚硝酸根

基于NOi_2~-可以与Pb~(2+)和SCN~-形成稳定的三元络合物,NO_2~-的存在会抑制Pb~(2+)的还原富集,使铅的微分溶出峰电流i_p~′减小,根据其减小值△i_p~′,可以间接测定NO_2~-。工作电极为玻碳电极,预电解电位为—0.75V(vs. SCE),铅的溶出峰电位为—0.5V(vs. SCE)。本文对测定条件,干扰及其消除方法进行了研究。测定下限为2×10~(-11) mol/L,大量硝酸根不干扰。     

Electrochemical Determination of Oxalate at Pyrolytic Graphite Electrodes

The electrocatalytic oxidation of oxalate at several carbon based electrodes including basal plane (BPPG) and edge plane (EPPG) pyrolytic graphite and glassy carbon (GC) electrode, was studied. The electrodes were examined for the sensing of oxalate ions in aqueous solutions and all three electrodes showed a response to oxalate additions. The peak of oxalate oxidation at BPPG electrode appeared at lower potential, +1.13 V vs. SCE, than at EPPG (+1.20 V vs. SCE) and GC electrode (+1.44 V vs. SCE). Oxalate oxidation at BPPG electrode was studied in more details for response characteristics (potential and current), effects of pH, temporal characteristics of response potential and current. The results indicated that oxalate oxidation proceeds as two‐electron process at the BPPG electrode with a transfer coefficient β and a diffusion coefficient D evaluated to be 0.45 and 1.03 (±0.04)×10^?5 cm² s^?1 respectively. The BPPG electrode was found to be suitable for oxalate determination in aqueous media showing linear response to oxalate concentration with a sensitivity of 0.039 AM^?1 and a limit of detection of 0.7 μM.     

Amperometric Glucose Biosensors Based on Glassy Carbon and SWCNT‐Modified Glassy Carbon Electrodes

Different carbonaceous materials, such as single‐walled carbon nanotubes (SWCNTs) and glassy carbon submitted to an electrochemical activation at +1.80 V (vs. SCE) for 900 s, have been used with the aim of comparing their performances in the development of enzyme electrodes. Commercial SWCNTs have been pretreated with 2.2 M HNO₃ for 20 h prior to use. The utility of activated GC as promising material for amperometric oxidase‐based biosensors has been confirmed. With glucose oxidase (GOx) as a model enzyme, glucose was efficiently detected up to 1 mM without the use of a mediator. Both electrodes operated in stirred solutions of 0.1 M phosphate buffer (pH 5.5), containing dissolved oxygen, at a potential of ?0.40 V vs. SCE. Although the performances of the two carbonaceous materials were comparable, the biosensors based on activated GC were characterized by a practically unchanged response 40 days after the fabrication, a better signal to noise ratio, and a little worse sensitivity. In addition, the preparation procedure of such biosensors was more simple, rapid and reproducible.     

Low Potential Detection of NADH at Titanium‐Containing MCM‐41 Modified Glassy Carbon Electrode

Titanium‐containing MCM‐41 (Ti‐MCM‐41) modified glassy carbon electrode (GCE) can exhibit an excellent electrocatalytic activity towards the oxidation of β‐Nicotinamide adenine dinucleotide (NADH). A dramatic decrease in the over‐voltage of NADH oxidation reaction is observed at 0.28 V (vs. SCE). The modified electrode is found to be stable and reproducible. The electrode shows a linear response for a wide range of 10–1200 μM NADH and the detection limit is 8.0 μM. Ti‐MCM‐41 mesoporous molecular sieves provide an efficient matrix for development of NADH biosensors and the prepared electrode not only can be used to detect the concentration of NADH in biochemical reaction, but also as the potential matrix of the construction of dehydrogenases biosensor.     

Detection of NADH and Ethanol at Titanium Containing MCM‐41 with Low Overpotential

Titanium‐containing MCM‐41 (Ti‐MCM‐41) modified glassy carbon electrode (GCE) can exhibit an excellent electrocatalytic activity towards the oxidation of β‐Nicotinamide adenine dinucleotide (NADH). A dramatic decrease in the overvoltage of NADH oxidation reaction is observed at 0.28 V vs. SCE. The application in the amperometric biosensing of ethanol using alcohol dehydrogenase enzyme (ADH) also has been demonstrated with this material. The proposed sensor shows a highly sensitivity, an acceptable reproducibility and a good stability. The linear range of ethanol is 25–1000 μM and the detection limit is 8.0 μM. Ti‐MCM‐41 modified electrode not only can be used to detect the concentration of NADH in biochemical reaction, but also as the potential matrix for the construction of dehydrogenases sensor.     

Electrocatalytic oxidation of NADH at mesoporous carbon modified electrodes

The electrochemical oxidation of β-nicotinamine adenine dinucleotide (NADH) was investigated at a glassy carbon electrode modified with carbon mesoporous materials (CMM). Due to the large surface area and electro-catalytic properties of CMM, the overpotential of the electrodes toward the oxidation of NADH is decreased by 595 mV in aqueous solution at neutral pH. The anodic peak currents increase steadily with the concentration of NADH in the range from 2 µM to 1.1 mM, the detection limit being 1.0 µM at pH 7.2 and a potential of +0.3 V vs. SCE. The apparent Michaelis-Menten constant is ～21.5 μM. The results enable NADH to be sensed at a low potential and are promising with respect to the design of dehydrogenase-based amperometric biosensors.     

Tuning the redox potential of riboflavin by zirconium phosphate in carbon paste electrodes

Modified carbon paste electrodes were prepared by inclusion of riboflavin together with zirconium phosphate (ZrP) into carbon paste. The midpoint potential for riboflavin in this electrode was found to be -0.259 V vs. SCE and shifted by 0.207 V to the positive direction, as compared to carbon paste electrode not containing ZrP. The electrode prepared was shown to electrocatalyse the anodic oxidation of the coenzyme NADH in the potential range of 0.0 to 0.25 V.     

3,6-二氧杂-1,8-辛二硫醇-汞(Ⅱ)配合物修饰碳糊电极的制备及循环伏安行为研究

利用3，6-二氧杂-1，8-辛二硫醇（H2L）和HgCl2反应，得到组成为Hg3L2Cl2的配合物。制备了Hg3L2Cl2修饰的碳糊电极，研究了在1mol／L KCl水溶液中的循环伏安行为。研究结果表明在1mol／L KCl介质中，在0．3～-0．8V（vs．SCE）范围内出现Hg3L2Cl2的还原和L^2-在汞膜表面的吸附，在一0．30—0．30V范围内出现汞膜的氧化还原反应。     

集流体对可充镁电池电解液电化学性能的影响

系统研究了铂、镍、不锈钢(SS)、铜、铝五种金属集流体和碳纤维、石墨箔、碳布三种碳纸集流体对“一代” (Mg(AlCl₂BuEt)₂/THF)、“二代” ((PhMgCl)₂-AlCl₃/THF)可充镁电池电解液阳极氧化分解电位和镁沉积-溶出性能的影响。金属镍、不锈钢、铜、铝作为可充镁电池正极的集流体时, 充电至一定电压时自身均会发生腐蚀。其中, 镍和不锈钢可用作充电电压在2.1V(vs Mg/Mg²⁺)以下正极材料的集流体; 铜可用作充电电压在1.8V(vs Mg/Mg²⁺)以下正极材料的集流体。碳集流体比金属集流体具有更高的稳定性, 其中, 碳布作为集流体, 适用于充电电压在2.25V(vs. Mg)(对“一代”电解液)和2.95V(vs Mg/Mg²⁺)(对“二代”电解液)以下的正极材料。     

姜黄素的电化学性质及其测定

在0.1 mol/L磷酸盐缓冲液(pH 3.0)中,姜黄素于玻碳电极上存在可逆的单电子转移过程,据此,本文建立了以差示脉冲伏安扫描法检测姜黄素含量的新方法.在+0.8V(vs.SCE)电位下,含姜黄素的电解液(试样)于玻碳电极上经过富集,可得一灵敏的还原峰,峰电位Ep为+0.386V.峰电流Ip与姜黄素浓度(1.0×10-8~2.5×10-7mol/L范围内)成线性关系,最低检出限为4.0×10-9mol/L.本法操作简单、快速、灵敏、准确,可用于药物中姜黄素含量直接测定.