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.     

Electrocatalytic Determination of Ampicillin Using Carbon-Paste Electrode Modified with Ferrocendicarboxylic Acid

Abstract

A carbon-paste electrode spiked with ferrocenedicarboxylic acid (FDCMCPE) was constructed by incorporation of ferrocenedicarboxylic acid in a graphite powder–paraffin oil matrix. It has been shown by direct current cyclic voltammetry and double-step chronoamperometry that this electrode can catalyze the oxidation of ampicillin (AMPC) in aqueous buffered solution. It has been found that under the optimum condition (pH 10.0) in cyclic voltammetry, the oxidation of AMPC occurred at a potential of about 480 mV on the surface of the modified carbon-paste electrode. The kinetic parameters such as electron-transfer coefficient, α, and rate constant for the chemical reaction between AMPC and redox sites in FDCMCPE were also determined using electrochemical approaches. Under the optimized conditions, the electrocatalytic oxidation peak current of AMPC showed two linear dynamic ranges with a detection limit of 0.67 µmol L^?1 AMPC. The linear calibration was in the range of 2.34–30 µmol L^?1 and 40–700 µmol L^?1 AMPC using the differential pulse voltammetric method. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of AMPC in real samples such as drugs and urine.     

酚类化合物在二氧化锡微粒修饰碳纤维电极上的氧化及检测

采用金属有机化学气相沉积技术制备了SnO2 修饰碳纤维微柱电极 ,讨论了电极的表面结构和稳定性 ,并利用循环伏安法分析了酚类化合物在电极上的电化学行为。该电极对酚类化合物有明显的电催化活性 ,并能防止酚类物质在碳纤维电极表面的电聚合。以 3 氯苯酚为测试物 ,其检测的线性浓度范围为 2× 10 -6～ 1.2× 10 -5mol/L     

一氧化氮在聚钴-席夫碱修饰电极上的电催化氧化

研究了一种新合成的杂环席夫碱Ｎ,Ｎ’－二乙酰吡啶缩双苯胺在铂电极上的电化学聚合、聚合膜与钴（Ⅱ）的配合反应及聚合物膜的电化学性质。实验结果表明,该席夫碱可在电极表面通过电化学聚合反应形成具有良好的机械、化学和电化学稳定性的聚合物膜,该聚合物膜可与钴离子形成稳定的配合物,这种配合物对和分子一氧化氮的电化学氧化有显著的催化作用。     

Electrocatalytic Oxidation of Nitric Oxide on an Electrode Modified with Fullerene Films

Fullerene was immobilized on the surface of a glassy carbon electrode and reduced by an electrochemical method to form a partially reduced fullerene film. The films on the electrode showed stable electrocatalytic activity towards the oxidation of nitric oxide (NO). The catalytic current was proportional to the concentration of nitric oxide. Based on this property, a method for the detection of nitric oxide in aqueous solution is proposed. The detection conditions, such as supporting electrolyte, scan rate and thickness of the film were optimized. Under the optimized conditions, the catalytic currents increase linearly with the concentration of NO in the range of 3×10^–71.0×10^–4M, and the detection limit is 7.4×10^–8M. In addition, the modified electrode is very selective with respect to interferences including ascorbic acid, dopamine, and nitrite when further modified by a Nafion film on the surface of the electrode. The experimental results indicate that the partially reduced fullerene can act as an NO sensor featuring fast response and high stability.     

Electrocatalytic Oxidation of Formaldehyde on Copper Oxide Nano-crystalline Modified Glassy Carbon Electrode

This research found a cheap and efficient catalyst for electrooxidation of formaldehyde (HCHO). A CuO nano‐crystalline modified glassy carbon electrode (GCE) was fabricated and had an excellent electrocatalytic activity towards the oxidation of HCHO. Both the effect of potential scan rate and the effect of HCHO concentration on the electrocatalytic oxidation performance of the electrode were investigated. The amperometric current response of the electrode was proportional to HCHO concentration in the range of 1.0 µmol·L^?1–10.0 mmol·L^?1 with a detection limit (s/n=3) of 0.25 µmol·L^?1. The electrode was stable, showing the CuO nano‐crystlline is promising for applications in fuel cells and electrochemical sensors.     

铂、钌共修饰的氧化钛电极对甲醇的电催化氧化

燃料电池;铂、钌共修饰的氧化钛电极对甲醇的电催化氧化     

Direct Electrocatalytic Oxidation of Cysteine and Cystine Based on Nafion/Lead Oxide‐Manganese Oxide Combined Catalyst

This article reports direct electrocatalytic oxidation of cysteine (CySH) and cystine (CyS‐SCy) at an inexpensive Nafion/lead oxide‐manganese oxide combined catalyst in physiological pH. The synthesized lead oxide‐manganese oxide material is simply mixed with Nafion in the form of cast solution and modified on a disposable screen‐printed carbon electrode (designated as SPE/Nf‐PMO) for biosensing application. Electrochemical study with a standard redox couple of quinone/hydroquinone demonstrates an enhanced current response at the combined catalyst compared to its individual component. Surface characterization further provides information regarding the structural morphology of the catalyst to its catalytic performance. Direct electrocatalytic oxidation signals are observed at +0.75 and +1.20 V vs. Ag/AgCl for cysteine and cystine, respectively, at the SPE/Nf‐PMO. To extend the applicability, we further apply the proposed system for the detection of cysteine and cystine by flow injection analysis (FIA). Under optimized conditions, the detection limit (S/N=3) is 0.43 μM and 0.33 μM for cysteine and cystine, respectively.     

Enhanced Electrocatalytic Oxidation of Paracetamol at DNA Modified Gold Electrode

Cysteine monolayer has been assembled onto bare gold electrode (SAM/Au), and subsequently deoxyribonucleic acid (DNA) has been successfully immobilized at the SAM/Au electrode. The thus modified electrode is assigned DNA/SAM/Au. Modification steps of the electrode were followed electrochemically using K₄[Fe(CN₆)] electrochemical marker. Also, the build‐up of the modified electrode composition is followed using EDX and the crystallographic orientation is inspected using XRD. The electrochemical behavior of paracetamol (PC) at DNA/SAM/Au electrode is investigated. Interestingly, the sluggish irreversible behavior of PC at the bare gold electrode is converted to a quasi‐reversible one at DNA/SAM/Au electrode pointing to some interaction between the immobilized DNA and PC. The enhanced electrochemical behavior of PC at modified DNA/SAM/Au electrode is successfully used for a sensitive electrochemical determination of PC. Square wave voltammetry (SWV) was used for this purpose. The concentration of PC was in linear relation with the peak current at the optimum conditions within the range 10.0–110.0 μg mL^?1 with correlation coefficient (R²) of 0.998. Also, the standard deviation (SD) and relative standard deviation (RSD) were calculated and found to be 0.817 and 1.52, respectively, indicating the significance of the present method.     

石墨烯修饰玻碳电极对多巴胺的电催化氧化

通过3-巯丙基三乙氧基硅烷(METMS)将氧化石墨烯(GO)固载到玻碳电极(GCE)表面, 用电化学方法还原GO制备石墨烯修饰玻碳电极(rGO-METMS-GCE). 利用傅里叶变换红外光谱(FTIR)、 拉曼光谱(Raman)、 扫描电子显微镜(SEM)和原子力显微镜(AFM)等技术对GO和rGO-METMS-GCE的结构和表面形貌进行表征. 采用循环伏安(CV)和差分脉冲溶出伏安(DPV)法研究了rGO-METMS-GCE对多巴胺(DA)的电催化氧化性能及反应机理. 结果表明, 与裸GCE相比, DA在rGO-METMS-GCE电极上的氧化还原峰电流(i_pa和i_pc) 增大4倍, 氧化峰电位负移106 mV, 氧化峰与还原峰电位差(ΔE_p)从202 mV降低至66 mV, DA电化学氧化可逆性明显改善, 表明rGO-METMS-GCE对DA电化学氧化具有显著电催化作用. DA在rGO-METMS-GCE上的反应机理为单电子转移过程.     

芦丁碳纳米管修饰玻碳电极电催化氧化肼的研究

应用循环伏安法研究了芦丁碳纳米管修饰玻碳电极(Rt-MWNT/GC)的电化学行为及其对肼的电催化氧化.实验表明,该修饰电极能使肼的氧化电位降至260 mV附近,表现出良好的电催化作用.安培法测得催化电流与肼浓度在2.5×10-6～1.0×10-4 mol·L-1范围内呈线性关系,检出限5×10-7 mol.L-1.     

银掺杂聚谷氨酸修饰电极对抗坏血酸的催化氧化

通过循环伏安法(CV)制备了银掺杂聚谷氨酸修饰玻碳电极(Ag/PGA/GCE),研究了抗坏血酸(AA)在该修饰电极上的电化学行为。结果表明:Ag/PGA/GCE对AA的氧化具有良好的电催化活性,可显著降低AA的氧化电位,同时增强AA的氧化峰电流。利用该修饰电极成功检测了药片中的AA含量。     

抗坏血酸在聚对羟基苯甲酸修饰玻碳电极上的催化电氧化行为

通过循环伏安(CV)制备了聚对羟基苯甲酸(poly-PHB)修饰的玻碳电极. 考察了电极对抗坏血酸(AA)电氧化的催化性能. 结果显示,聚对羟基苯甲酸修饰玻碳电极对AA氧化有很好的电催化作用. 在修饰电极上产生的峰电流比在未修饰电极上产生的氧化峰电流大4倍,氧化峰电位负移205 mV. 氧化峰电流与AA浓度在2.6×10-5～3.68 ×10-4 mol/L范围内呈线性关系,相关系数为0.998 4,检测限为5×10-6 mol/L(S/N=3). 在AA与多巴胺(DA)共存的体系中,能排除DA对抗坏血酸测定的干扰.     

Electrocatalytic Oxidation and Determination of Norepinephrine at Poly(Cresol Red) Modified Glassy Carbon Electrode

A glassy carbon electrode (GCE) was modified with electropolymerized films of cresol red in pH 5.6 phosphate buffer solution (PBS) by cyclic voltammetry (CV). The modified electrode shows an excellent electrocatalytic effect on the oxidation of norepinephrine (NE). The peak current increases linearly with the concentration of NE in the range of 3×10^?6–3×10^?5 M by the differential pulse voltammetry. The detection limit was 2×10^?7 M. The modified electrode can also separate the electrochemical responses of norepinephrine and ascorbic acid (AA). The separation between the anodic peak potentials of NE and AA was 190 mV by the cyclic voltammetry. And the responses to NE and AA at the modified electrode were relatively independent.     

CO在铂修饰的氧化钛电极上电催化氧化行为的研究

通过阴极还原-阳极氧化法制备了Pt—TiO2／Ti电极，研究了CO在该电极上的电化学行为和电极制备条件对CO电催化氧化的影响．结果表明，与Pt电极相比．CO在Pt—TiO2／Ti电极上的氧化峰峰电位负移了100mV，并且表现出较好的稳定性．通过XPS技术对Pt—TiO2／Ti电极进行了表征．发现Pt以金属形式存在，Ti以TiO2形式存在．Pt—TiO2／Ti电极能抗CO中毒的原因可能是因为TiO2的掺杂使引起催化剂中毒的桥式吸附的CO物种在复合催化剂上的吸附率较低所致．     

碳纳米管修饰电极上沙丁胺醇电催化氧化研究

将多壁碳纳米管(MWNT)分散在疏水性表面活性剂双十六烷基磷酸(DHP)溶液中形成稳定、均相的分散液,然后制备多壁碳纳米管-DHP复合膜修饰玻碳电极(MWNT-DHP/GCE).应用方波伏安法研究了沙丁胺醇在修饰电极上的电化学行为,结果表明,碳纳米管复合膜修饰电极对沙丁胺醇的氧化有良好的电催化活性,其氧化反应为一电子一质子过程,氧化电位比裸玻碳电极负移40 mV,峰电流增加了4.5倍.在最佳测试条件下,氧化峰电流与沙丁胺醇浓度在8.3×10-7~3.3×10-6mol/L范围内呈良好线性关系,开路富集2min,检出限达1.8×10-7mol/L.该修饰电极具有良好的重现性、稳定性.     

N-乙酰-L-半胱氨酸在咖啡酸修饰碳糊电极上的电催化氧化

研究了N-乙酰-L-半胱氨酸（N-acetyl-L-cysteine,NAC）在咖啡酸（CFA）修饰碳糊电极（CFA/CPE）上的电催化行为。结果表明,NAC在裸碳糊电极（CPE）上的直接电化学氧化过程十分迟缓,而CFA/CPE对NAC的电化学氧化具有良好的催化作用。用循环伏安法（CV）、计时电流法（CA）测定了NAC在CFA/CPE上的电极过程动力学参数。电荷传递系数α=0.79,电催化氧化反应速率常数k=（4.40±0.10）×10^3（mol.L^-1）^-1.s^-1。用微分脉冲伏安法（DPV）测得催化氧化峰电流与NAC浓度在1.0×10^-6～7.5×10^-4mol.L^-1范围内呈良好的线性关系,线性回归方程为Ipa（μA）=4.075c（mmol.L^-1）＋2.671,r=0.9988,检出限为1.7×10^-7mol.L^-1。用该方法对市售药品富露施中的NAC含量进行测定,结果令人满意。     

碳纳米管负载纳米铂修饰电极及电催化氧化H2O2的研究

采用化学气相沉积法在碳纳米管(CNT)上负载Pt纳米颗粒,并制备了CNT-Pt修饰玻碳电极(CNT-Pt/GCE).研究了该修饰电极在磷酸缓冲液中对H2O2的电催化氧化作用以及实验条件的影响.计算了H2O2在CNT-Pt/GCE上的电极反应速率常数.结果表明,CNT-Pt/GCE对H2O2的电化学氧化具有良好的催化作用,电极反应速率常数比铂电极高约2.65倍.初步探讨了电催化氧化机理,为酶电化学传感器的研制提供了一条新的途径.     

铁氰化钆修饰电极对鸟嘌呤的电催化氧化及应用

用电化学沉积法制备了稀土铁氰化钆修饰玻碳电极(GdHCF/GC/CME),考察了该电极对鸟嘌呤的电催化氧化性能,同时根据Fenton反应产生的羟基自由基对鸟嘌呤的氧化作用和修饰电极氧化作用之间的竞争机理,对抗坏血酸清除羟基自由基进行了初步评价.实验结果表明,修饰电极对鸟嘌呤具有很好的电催化氧化性能.在HAc-NaAc缓冲液(pH=5.1)中,鸟嘌呤在1.0×10-6～4.6×10-5 mol/L浓度范围内与其氧化峰电流呈良好的线性关系,其线性回归方程为Ip(μA)=0.1112C 2.8715,r=0.9889;检出限为3.3×10-7 mol/L.以此电极评价抗坏血酸对羟基自由基的清除作用,取得了较好的效果,为羟基自由基清除剂的筛选提供了一种新的方法.