TiN基IrO2-Ta2O5涂层析氢电极的催化性能

 采用热分解法制备了以离子镀TiN膜为基体的IrO2-Ta2O5涂层电极,通过循环极化曲线并结合扫描电镜、 X射线能谱和X射线衍射研究了涂层的析氢电催化性能. 结果表明,涂层呈多孔多裂纹的结构,焙烧温度对涂层的表面形貌和电催化活性影响很大. 420 ℃下焙烧的涂层具有最优的电催化活性. 涂层电极的析氢反应电极电位为-0.26 V(vs SCE), 低析氢过电位下的Tafel斜率为-0.04 V, 而在高析氢过电位下,电极表面吸附的大量氢原子改变了氧化物电极的结构,从而抑制了氧的阴极还原反应.     

铂电极上吸附芳香分子的表面增强红外光谱研究

应用衰减全反射表面增强红外吸收光谱法分别研究了0.1 mol•L^－1 HClO₄中对硝基苯甲酸(PNBA)和0.1 mol•L^－1 KClO₄中吡啶(Py)在铂电极上的吸脱附. 结果表明在较高电位下(0.3～0.7 V vs. SCE) PNBA是通过其羧基脱质子后羧酸根的两个氧原子等位吸附在Pt电极表面, 而随着电位的负移, 除PNBA逐步脱附外, 还呈现出单个氧原子吸附的谱学特征. 光谱强度与电位的关系表明PNBA在铂电极表面吸脱附的中间电位约为0.2 V vs. SCE. 吡啶的吸附主要是通过氮原子的孤对电子及脱氢后的α碳原子与Pt电极表面键合. 在较宽的电位区间(0.4～－0.4 V vs. SCE)吡啶的吸附方式和取向基本维持不变.     

铂电极上锑吸附原子对1,2-丙二醇电催化氧化性能的影响

运用电化学循环伏安(CV)和电化学原位石英晶体微天平(EQCM)研究了Pt电极表面不可逆吸附Sb原子的电化学特性以及Pt电极上Sb吸附原子对0.1mol·L-1H2SO4溶液中1,2 丙二醇电催化氧化性能的影响.研究发现,当扫描电位的上限Eu≤0.50V(SCE)时,Sb可以稳定地吸附在Pt电极表面,饱和覆盖度为0.34;通过控制电位扫描上限和扫描圈数剥离部份Sb可方便地得到Sbad的不同覆盖度;Pt电极表面Sb吸附原子能在较低的电位下吸附氧,可显著提高1,2 丙二醇电催化氧化活性.与Pt电极相比较,Sb饱和吸附原子修饰的Pt电极使1,2 丙二醇氧化的峰电流增加了近2倍.作者还从表面质量变化提供了吸附原子电催化作用的新数据.     

酸性和碱性介质中甘氨酸解离吸附和氧化的EQCM研究

用电化学石英晶体微天平(EQCM)研究酸性和碱性介质中甘氨酸在Pt电极上的吸附和氧化过程.结果表明,甘氨酸的解离吸附和氧化行为与溶液的酸碱性密切相关.酸性溶液中甘氨酸吸附较弱,碱性溶液中则产生强吸附物,且当电位低于0V(vs.SCE)时可吸附于Pt电极表面.此外,碱性溶液中甘氨酸还表现出较高的电氧化活性.通过EQCM定量检测上述过程中Pt电极表面的质量变化,测定了不同电位区间(氢区、双电层区和氧区)每传递一个电子所对应的电极表面吸附物种的平均摩尔质量.     

血红蛋白在碳纳米管修饰碳糊电极上的直接电化学行为

利用吸附法将血红蛋白(Hb)固定在碳纳米管修饰碳糊电极表面,制成稳定的固载Hb碳纳米管修饰电极,研究了Hb在碳纳米管修饰电极上的直接电化学行为.固载Hb的碳纳米管修饰电极在pH=7.0的PBS（磷酸盐缓冲溶液）中有一对相当可逆的循环伏安氧化还原峰,为Hb血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰.式电位为－0.160 V(vs SCE),随扫描速度变化很小.电子转移数为1.021,近似为一个辅基发生电子转移.Hb在碳纳米管修饰电极表面的电子转移常数为0.0816 s－1,远大于亚甲蓝作媒介体时Hb的电子转移反应速率常数.应用于过氧化氢、三氯乙酸和硝基苯等的电催化还原,固定在碳纳米管修饰碳糊电极的血红蛋白表现出稳定且较高的催化活性.     

碳纳米管修饰电极上葡萄糖氧化酶的直接电子转移

制备了碳纳米管修饰玻碳电极(CNT/GC), 利用吸附的方法将葡萄糖氧化酶(GOx)固定到CNT/GC电极表面, 形成GOx-CNT/GC电极．研究了GOx的直接电子转移, 实验结果表明, GOx在CNT/GC电极表面没有发生变性, 能进行有效和稳定的直接电子转移反应, 其循环伏安图上表现出一对很好的、几乎对称的氧化还原峰; 式量电位E^0’几乎不随扫速(至少在10~140 mV·s^−1的扫速范围内)而变化, 其平均值为−0.456±0.0008 V (vs. SCE); GOx在CNT/GC电极表面直接电子转移的速率常数为1.74±0.42 s^−1, 比文献中报道的值大了数十倍; 进一步的实验结果显示, 固定在CNT/GC电极表面的GOx能保持其对葡萄糖氧化的生物电催化活性, 而且电催化活性很稳定. 文中制备碳纳米管修饰电极和固定酶的方法具有简单和易于操作等优点, 可用于获得其他生物氧化还原蛋白质和酶的直接电子转移.     

FeCl_2-K_2MoS_4体系电催化还原乙炔为乙烯

采用控电位电解、循环伏安法和交流阻抗法研究了FeCl_2-K_2MoS_4体系对乙炔在石墨电极上还原为乙烯的电催化活性及反应机理。实验结果表明,当石墨阴极的电位控制在-1.50V(vs.SCE)时,FeCl_2+K_2MoS_4的DMF溶液对C_2H_2还原为C_2H_4表现出明显的电催化活性和高的选择性。在-0.5～-1.0V时Mo(Ⅵ)还原为Mo(Ⅴ);在按连串的电子传递机理进行的Mo(Ⅴ)→Mo(Ⅲ)反应的电位区间(-1.0～-1.50V)溶液中所形成的络合品种传递电子的能力更强。Mo(Ⅲ)可能是络合物的电活性成分。     

二氢辅酶的电催化氧化: I: α-萘甲酰尼罗蓝修饰电极性能研究

新的电子传递中间体α-萘甲酰尼罗蓝(NNB)能强烈吸附在石墨上以构成修饰电极。在-0.5V至+0.6V(vs. SCE)电位区内, 固定化的NNB表观出相当可逆的氧化还原行为, 总反应中有2个电子和2个质子参加。在pH7.0缓冲溶液中其表面标准电位E°'为-170mV, 表观电子传递常数kg为3s^-^1。NNB对还原辅酶NADH的电化学氧化有明显催化作用, 可使氧化过电位降低550mV。NADH的电催化遵循EC机理, 催化反应步骤为速度决定步骤, 其速度常数为3×10^3dm^3.mol^-^1.s^-^1。NNB在中性和弱碱性介质中的稳定性优于其它电子传递中间体, 是有前途的电催化剂。     

二氢辅酶的电催化氧化: I: α-萘甲酰尼罗蓝修饰电极性能研究

新的电子传递中间体α-萘甲酰尼罗蓝(NNB)能强烈吸附在石墨上以构成修饰电极。在-0.5V至+0.6V(vs. SCE)电位区内, 固定化的NNB表观出相当可逆的氧化还原行为, 总反应中有2个电子和2个质子参加。在pH7.0缓冲溶液中其表面标准电位E°'为-170mV, 表观电子传递常数kg为3s^-^1。NNB对还原辅酶NADH的电化学氧化有明显催化作用, 可使氧化过电位降低550mV。NADH的电催化遵循EC机理, 催化反应步骤为速度决定步骤, 其速度常数为3×10^3dm^3.mol^-^1.s^-^1。NNB在中性和弱碱性介质中的稳定性优于其它电子传递中间体, 是有前途的电催化剂。     

草酸在铂基Sb-Pb表面合金电极上的催化还原

将Sb Pb Pt/GC表面合金电极应用于草酸的电催化还原,发现所制备的催化剂电极具有较高的电催化活性,草酸还原的起始电位约－0.4 V,与通常使用的铅阴极相比,正移了大约600 mV.电化学原位红外反射光谱研究,证实所研制的催化剂可在较低的过电位下还原草酸生成乙醛酸,并具有较好的选择性.对于所研制的表面合金电催化剂的实际应用进行了探讨.     

Electroreduction of 6-amino-5-nitroso-1,3-dimethyluracil on an active carbon fiber electrode in caffeine green synthesis

The primary electroreduction behavior of 6-amino-5-nitroso-1,3-dimethyluracil (ANDMU) on an active carbon fiber (ACF) electrode in acidic aqueous solution was studied by cyclic voltammetry and ultraviolet spectrophotometry for application in electrochemical synthesis and electrosorption separation in the caffeine industry. On the ACF electrode at potentials more negative than ?0.3 V versus SCE, ANDMU could be electro-reduced to 5,6-diamino-1,3-dimethyluracil. The mechanism of electroreduction of ANDMU is possibly coupling of two electron-transfer steps with electrocatalytic hydrogenation. ANDMU could also be electro-oxidized on an ACF electrode at potentials more positive than 0.8 V versus SCE. The potential window of ANDMU on the ACF electrode is deduced to be ?0.3 to 0.8 V versus SCE under these experimental conditions. The results are indicative of high feasibility of electrochemical hydrogenation of ANDMU on an ACF electrode in caffeine green synthesis.     

Direct Electrochemistry of Hemoglobin and Its Electrocatalysis Based on Hyaluronic Acid and Room Temperature Ionic Liquid

A biocomposite material of hyaluronic acid (HA) and room temperature ionic liquid, 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate (BMIMBF₄) was fabricated and characterized by voltammetry and electrochemical impedance spectroscopy. Hemoglobin (Hb), as a model protein, was immobilized in this biocomposite on glassy carbon electrode to investigate its direct electrochemistry. A pair of well‐defined, quasireversible cyclic voltammetric peaks appeared with the formal potentials (E°′) at ?0.360 V (vs. SCE). The Hb modified electrode exhibited an excellent electrocatalytic activity to the reduction of H₂O₂ with a wide linear range, good selectivity, sensitivity and reproducibility, which had potential application to fabrication the third‐generation biosensor.     

吲哚美辛在单壁碳纳米管修饰电极上的电化学行为

运用伏安法研究了吲哚美辛在单壁碳纳米管修饰电极上的电化学行为.在0.1 mol/L HAc-NaAc缓冲溶液(pH 4.5)中,吲哚美辛于0.91 V (vs.SCE)电位处有一个峰形很好的氧化峰.与裸玻碳电极相比,吲哚美辛在修饰电极上的电位正移了约30 mV,峰电流增加了近10倍,表明该修饰电极对吲哚美辛有较强的电催化作用.搅拌条件下开路富集2 min,氧化峰电流与吲哚美辛在5.5×10-7～1.1×10-5 mol/L浓度范围内呈良好的线性关系,检出限为1.1×10-7 mol/L.该方法可用于药剂中吲哚美辛的分析.     

Sb在Au电极上不可逆吸附的电化学过程

用电化学循环伏安法和电化学石英晶体微天平(EQCM)技术研究了Sb在Au电极上不可逆吸附的电化学过程. 研究结果表明, 在-0.25 V到0.18 V(vs SCE)范围内, Sb可在Au电极上稳定吸附, 并且在0.15 V附近出现特征氧化还原峰. 根据EQCM实验数据, 在电位0.18 V时, Sb在Au电极上的氧化产物是Sb2O3; 同时Sb的吸附阻止了电解液中阴离子和水在Au电极上的吸附. 当电极电位超过0.20 V时, Sb2O3会被进一步氧化成Sb5+化合物, 同时逐渐从Au电极表面脱附.     

Adjustable bidirectional extracellular electron transfer between Comamonas testosteroni biofilms and electrode via distinct electron mediators

Bidirectional extracellular electron transfer of strain Comamonas testosteroni I2 was for the first time investigated with electrochemical active biofilms developed under different conditions. The electrochemical active biofilm developed under microbial fuel cell conditions was capable of anodic electron transfer via attached redox species with standard potential of 0.04 V (vs. SCE). Meanwhile the above redox species lost its catalytic capability when the biofilm was developed under a constant potential (− 0.4 V vs. SCE). Instead, the microbe adjusted its electron transfer strategy to a soluble shuttle (standard potential − 0.20 V vs. SCE) and enabled a cathodic current. Air exposure experiment verified that the soluble shuttle at negative potential had a positive response to the oxygen; meanwhile the anodic electron transfer via the attached species was rarely influenced.     

乙二醛在Ti/纳米TiO2-Pt修饰电极上的电催化氧化

采用溶胶-凝胶和电沉积法制备Ti基纳米TiO2-Pt(Ti/纳米TiO2-Pt)修饰电极. X射线衍射(XRD)表明纳米TiO2为锐钛矿型, 扫描电镜(SEM)显示Pt纳米粒子在纳米TiO2多孔膜的表面呈现簇分散状态, 平均粒径约25 nm. 通过循环伏安(CV)和计时电流法研究了Ti/纳米TiO2-Pt修饰电极对乙二醛直接电氧化的电催化活性, 结果表明, 修饰电极对乙二醛的直接电氧化呈现良好的催化活性, 在0.60和1.23 V(vs SCE)出现两个氧化峰, 二者电流密度分别为16 和42 mA·cm-2, 约为纯Pt电极的2倍和1.5倍, 反应过程受浓差扩散控制.     

Direct Electrochemistry of Hemoglobin Immobilized in Sodium Alginate Film on the Ionic Liquid [BMIM]PF6 Modified Carbon Paste Electrode

In recent years the direct electron transfer of redox protein on electrode surface has attracted great attentions1. Different kind of modified electrode and various supporting films for immobilization of proteins had been proposed. But most of them are ba…     

Electrochemical and Spectroelectrochemical Studies on Pyridoxine Hydrochloride Using a Poly(methylene blue) Modified Electrode

The electrochemical redox processes of pyridoxine hydrochloride (VB₆) at a poly(methylene blue) film modified glass carbon electrode (PMBE) in a phosphate buffer solution (PBS, pH 8.0) were studied by cyclic voltammetry. The VB₆ electrode reaction with quasi‐reversible characteristics was diffusion‐controlled at low scan rates and adsorption‐controlled at high scan rates. The anodic peak current positive to 0.6 V (vs. SCE) was found to be proportional to the concentration of VB₆ in the range of 0.010 to 1.03 mg?mL^?1 with a detection limit of 1.34 μg mL^?1. Fluorescence and UV‐vis absorption spectroelectrochemical measurements suggest that the pyridine ring was not destroyed over the potential range from ?0.8 to 1 V (vs. SCE), and the electrocatalytic generation of pyridoxal was anodically started at 0.57 V.     

Electrochemical Behavior of Irreversibly Adsorbed Sb on Au Electrode

The electrochemical processes of irreversibly adsorbed antimony (Sb_ad) on Au electrode were investigated by cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). CV data showed that Sb_ad on Au electrode yielded oxidation and reduction features at about 0.15 V (vs saturated calomel electrode, SCE). EQCM data indicated that Sb_ad species were stable on Au electrode in the potential region from −0.25 to 0.18 V (vs SCE); the adsorption of Sb inhibited the adsorption of water and anion on Au electrode at low electrode potentials. Sb₂O₃ species was suggested to form on the Au electrode at 0.18 V. At a potential higher than 0.20 V the Sb₂O₃ species could be further oxidized to Sb(V) oxidation state and then desorbed from Au electrode.     

碳载Pt/Sb_(ad)电极上乙醇电催化氧化特征和原位FTIR反射光谱研究

用电化学循环伏安法和原位 FTIR反射光谱法研究了 Sb在碳载纳米 Pt膜电极 (nm -Pt/ GC)表面不可逆吸附的电化学特性及酸性介质中乙醇的吸附和电催化氧化特性 .结果指出 ,当扫描电位的上限 Eu≤0 .5 0 V(SCE)时 ,Sbad可以稳定地吸附在 nm-Pt/ GC电极表面 .与未修饰的 nm-Pt/ GC电极上结果相比 ,Sbad修饰的 nm-Pt/ GC/ Sbad/ (nm-Pt/ GC)的催化活性显著增加 .测得当覆盖度θsb=0 .1 3 7时 ,修饰电极对乙醇的电催化活性最高 ,乙醇氧化的峰电位负移了 0 .1 5 V,峰电流增大了 1倍 .原位 FTIR反射光谱的结果从分子水平揭示了 Sb修饰对乙醇氧化反应途径的选择功能 .