新型的钛基Ni-Sn/Ti电极的制备及对甲醇氧化反应的电催化活性

利用电热法,一步制备出新型的钛基Ni-Sn/Ti电极(Ni8Sn/Ti, Ni7Sn3/Ti 和 Ni/Ti)。扫描电镜（SEM）图像表明,催化剂以片状的纳米颗粒形式沉积于钛基体上。利用电化学伏安技术、电位阶跃法和电化学交流阻抗谱（EIS）,研究了这些电极在1mol.L�1NaOH溶液中对甲醇氧化反应的电催化活性。研究表明,与Ni7Sn3/Ti,Ni/Ti以及多晶镍电极相比,Ni8Sn/Ti电极对甲醇氧化反应表现出更高的阳极氧化电流和更低的起始电位。EIS分析表明,在本文所考察的阳极电位和甲醇浓度下,Ni8Sn/Ti电极对甲醇氧化反应显示出极低的电荷传递电阻。结果表明,这种新型的钛基Ni8Sn/Ti电极对甲醇氧化反应具有极高的电催化活性。     

钛基纳米多孔金电极对甲醛氧化的电催化活性

采用水热法制备了钛基纳米金微粒修饰电极(Au/Ti)。扫描电镜图表明纳米金颗粒粒径大约为300 nm,在钛基体表面构成三维多孔网状结构。运用循环伏安,电位阶跃和交流阻抗等电化学技术研究了碱性介质中甲醛在Au/Ti电极上的电氧化行为。循环伏安图显示,甲醛在Au/Ti上的起始氧化电位在-0.90 V左右,相对于多晶金电极提前大约0.2 V,交流阻抗测试表明,甲醛在Au/Ti电极上电氧化表现出低的电荷传递电阻。研究结果表明钛基纳米金微粒修饰电极对甲醛氧化具有良好的电催化活性。     

Co3O4/Ti电催化膜电极制备及其苯甲醇催化氧化性能

本文采用浸渍涂覆法成功制备出多孔Ti负载纳米Co₃O₄电催化膜电极（Co₃O₄/Ti）,以该膜电极为阳极,辅助电极为阴极,构建电催化膜反应器（electrocatalytic membrane reactor,ECMR）用于可控催化氧化苯甲醇制备苯甲醛和苯甲酸,并考察了 Co₃O₄/Ti 膜电极结构、电化学性能以及ECMR不同操作参数对苯甲醇转化率、苯甲醛和苯甲酸选择性的影响. 结果表明,负载Co₃O₄纳米颗粒可以显著提高Ti膜电极的电化学性能和催化活性. 在常温常压下,当反应物苯甲醇浓度为10 mmol·L^-1,pH为7.0,停留时间为5.0 min,电流密度为2.5 mA·cm^-2,苯甲醇的转化率达到49.8%,苯甲醛选择性为51.5%,苯甲酸选择性为23.6%.     

脉冲电沉积钯镍合金纳米颗粒及其甲酸电催化氧化

采用方波脉冲方法,在钯镍合金电解液中成功地电化学沉积出镍原子含量分别为12.0%、16.4%和22.6%的钯镍合金纳米颗粒.钯镍合金纳米颗粒为球状,粒径50~80 nm.随钯镍合金生长电位负移,合金的镍含量提高,其纳米颗粒大小基本相似但纳米颗粒数目增多,交联度提高和真实活性面积增大.钯镍合金纳米颗粒镍含量提高,在硫酸溶液中其氢弱吸附峰电流增大.钯镍合金纳米颗粒电极的甲酸电催化氧化活性较好,随合金纳米颗粒的镍含量提高和交联度增加,合金纳米颗粒电极的甲酸电催化氧化稳定性更高.     

脉冲电沉积Pd-Ni合金纳米颗粒及其甲酸电催化氧化

采用方波脉冲方法,在钯镍合金电解液中成功地电化学沉积出镍原子含量分别为12.0%、16.4%和22.6%的钯镍合金纳米颗粒. 钯镍合金纳米颗粒为球状,粒径50 ~ 80 nm. 随钯镍合金生长电位负移,合金的镍含量提高,其纳米颗粒大小基本相似但纳米颗粒数目增多,交联度提高和真实活性面积增大. 钯镍合金纳米颗粒镍含量提高,在硫酸溶液中其氢弱吸附峰电流增大. 钯镍合金纳米颗粒电极的甲酸电催化氧化活性较好,随合金纳米颗粒的镍含量提高和交联度增加,合金纳米颗粒电极的甲酸电催化氧化稳定性更高.     

Ti基纳米TiO_2-CNT-Pt复合电极制备、表征及电化学性能

以电合成前驱体Ti(OEt)4直接水解法和电化学扫描电沉积法制备Ti基纳米TiO2-CNT-Pt(Ti/nanoTiO2-CNT-Pt)复合电极.透射电镜(TEM)和X射线衍射(XRD)测试表明,锐钛矿型纳米TiO2粒子(粒径5～10nm)和碳纳米管(CNT)结合形成网状结构,Pt纳米粒子(平均粒径9nm)均匀地分散在纳米TiO2-CNT复合膜表面.循环伏安及计时电流测试表明,Ti/nanoTiO2-CNT-Pt复合电极具有高活性表面,对甲醇的电化学氧化具有高催化活性和稳定性,Pt载量为0.32mg/cm2时,常温常压下甲醇氧化峰电流达到480mA/cm2.     

甲醇在铂修饰的氧化钛电极上电催化氧化行为的研究

运用电化学方法评价了电化学阴极还原-阳极氧化两步法制得的以钛为基体的铂修饰的钛氧化物(Pt-TiO_x/Ti)电极对甲醇电催化氧化的性能,结果表明,制得的修饰电极对甲醇氧化呈现了很高的电催化活性和好的稳定性.通过X光电子能谱(XPS)、扫描隧道显微镜(STM)和现场傅立叶变换红外(FTIR)反射光谱等技术,发现修饰电极对甲醇氧化具有高的电催化性能,可归属于纳米级Pt粒子在TiO_x中的高度分散及由于Pt和TiO_x的相互作用,使电极表面对甲醇氧化中间产物CO的吸附量大大降低.     

Pd/Fe3O4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容。本文用硼氢化钠还原法制备了钯纳米颗粒, 然后沉积在Fe3O4/C复合物表面, 得到了不同Fe₃O₄负载量的Pd/Fe₃O₄-C催化剂. 透射电镜（TEM）图显示钯纳米颗粒均匀地分散在Fe₃O₄/C表面. 对制备好的Pd/Fe₃O₄-C催化剂进行了循环伏安法（CV）、计时电流（CA）和电化学阻抗谱（EIS）的测试, 研究了其在碱性介质中对C1-C3醇类（甲醇、乙醇和丙醇）氧化的电催化活性. 结果表明, 所制备的不同Fe₃O₄负载量的Pd/Fe₃O₄(2%)-C,Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C和Pd/C催化剂中, Pd/Fe₃O₄(5%)-C催化剂表现出最高的醇氧化电流密度. 依据循环伏安（CV）数据,Pd/Fe₃O₄(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍. Pd/Fe₃O₄(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂. 制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下: 正丙醇﹥乙醇﹥甲醇﹥异丙醇. 此外, 碳粉中Fe₃O₄纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.     

辐射状钯纳米花的可控合成及其电催化性能的研究

水体系中,以十六烷基三甲基溴化铵(CTAB)和L-精氨酸为表面活性剂,抗坏血酸还原PdCl42-,制得了直径范围在50~80 nm之间的辐射状钯纳米花.实验表明,CTAB和L-精氨酸对辐射状钯纳米花的形成起着协同作用.此外,还研究了辐射状钯纳米花对甲酸氧化的电催化活性.在0.5 mol/L H2SO4+0.5 mol/L HCOOH溶液中的循环伏安结果表明,辐射状钯纳米花修饰电极在酸性溶液中电催化氧化甲酸的峰电流密度约为101 mA/mg,明显优于实心钯纳米粒子修饰的电极(峰电流密度为50 mA/mg),且表现出较高的稳定性.     

Pd/Fe_3O_4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性（英文）

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容.本文用硼氢化钠还原法制备了钯纳米颗粒,然后沉积在Fe_3O_4/C复合物表面,得到了不同Fe_3O_4负载量的Pd/Fe_3O_4-C催化剂.透射电镜(TEM)检测显示,钯纳米颗粒均匀地分散在Fe_3O_4/C表面.对制备好的Pd/Fe_3O_4-C催化剂进行了循环伏安法(CV)、计时电流(CA)和电化学阻抗谱(EIS)的测试,研究了其在碱性介质中对C1-C3醇类(甲醇、乙醇和丙醇)氧化的电催化活性.结果表明,所制备的不同Fe_3O_4负载量的Pd/Fe_3O_4(2%)-C、Pd/Fe_3O_4(5%)-C、Pd/Fe_3O_4(10%)-C和Pd/C催化剂中,Pd/Fe_3O_4(5%)-C催化剂表现出最高的醇氧化电流密度.依据循环伏安(CV)数据,Pd/Fe_3O_4(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍.Pd/Fe_3O_4(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂.制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下:正丙醇乙醇甲醇异丙醇.此外,碳粉中Fe_3O_4纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.     

Preparation and Electrochemical Properties of the Pd-modified Cu Electrode for Nitrate Reduction in Water

The reduction of nitrate has gained renewed attention due to environmental problems like overfertilization and the increasing costs of purification of drinking water. The usual techniques (e.g. ion-exchange and biofiltration) have some disadvantages1. So …     

Formation and electrocatalytic properties of Pd deposits on Mo obtained by galvanic displacement

A Pd-Mo electrocatalytic system was obtained by forming palladium particles on the Mo surface that contacted a PdCl₂ solution under open-circuit conditions. The state of palladium on the electrode surface depended on the contact displacement time. Palladium particles 5–10 nm in size formed on the surface of the Pd(Mo) electrode after palladium deposition for 1 min. The specific rates of formic acid oxidation on the Pd(Mo) electrode were smaller than those on the Pd/Pt electrode. On the Pd(Mo) electrode, anode currents of methanol oxidation were recorded at a potential of 0.4 V. The difference in the effects of the Mo substrate on the activity of Pd particles in the electrooxidations of HCOOH and CH₃OH was explained by the difference in the mechanisms of these reactions.     

Preparation of palladium nanoparticles–titanium electrodes as a new anode for direct methanol fuel cells

Pd nanoparticle/Ti electrodes are prepared by electroless plating of palladium on titanium plates. The morphology and surface analysis of Pd nanoparticle/Ti electrodes are investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The results indicate that palladium nanoparticles are homogeneously deposited on the surface of titanium plates. The electro-catalytic activity of Pd nanoparticle/Ti electrodes in the methanol electro-oxidation is studied by cyclic voltammetry and chronoamperometry methods. The results show that the electro-catalytic oxidation of methanol on the Pd nanoparticle/Ti electrode improved compare to pure palladium electrode and confirmed the better electro-catalytic activity and stability of these new electrodes.     

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.     

纳米钯膜电极的制备、结构表征和特殊反应性能

用循环伏安方法制备纳米钯膜电极,运用扫描隧道显微镜和原位红外光谱等方法研究其结构和反应性能.STM图像表明,制备的纳米钯膜具有特殊的层状结构,纳米级厚度的层状晶体由直径6nm左右的Pd微晶聚集而成.发现当钯膜厚度为几个纳米时,CO的吸附表现出异常红外效应,即红外谱峰反向和红外吸收显著增强(增强因子可达42.6).纳米钯膜电极对氢的反应也具有特殊的性能,与氢向钯晶格扩散吸收过程相比较,氢吸脱附的表面过程成为主要反应.研究结果还指出,纳米钯膜电极的异常红外效应和对氢反应的特殊性能与钯膜厚度密切关联,并可归结为钯膜材料的纳米尺度效应.     

电沉积-置换法制备Pt/Ti对电极及其对染料敏化太阳能电池性能的提升

采用电沉积-置换法在Ti片上制备了染料敏化太阳能电池(DSSC)的对电极Pt/Ti. 形貌表征结果显示, 与传统热解法制备的Pt/FTO对电极相比, Pt/Ti对电极Ti基底上Pt催化颗粒的粒径和分散性得到显著改善. 光电流-光电压特性曲线测试结果表明, 以Pt/Ti为对电极的DSSC与以Pt/FTO为对电极的DSSC相比, 光电转化效率提高了20.8%. 由于Pt颗粒分散性和粒径的改善所引起的Pt催化性能的提高、 Pt/Ti对电极更低的电阻以及Ti基底更好的反光性能是提升DSSC性能的原因.     

Electrocatalytic activity of a novel titanium-supported nanoporous gold catalyst for glucose oxidation

A novel Ti-supported gold catalyst (nanoAu/Ti) with a nanoporous 3D texture has been fabricated using a hydrothermal method. Au particles were stably deposited on the Ti surface from the mixture of aqueous tetrachlororoauric acid and polyethylene glycol at 180 °C. Voltammetry (CV) and chronoamperometry were used to characterize the nanoAu/Ti electrode and assess its electroactivity towards glucose oxidation. Compared to polycrystalline Au, the nanoAu/Ti electrode shows similar CV profiles in alkaline solution. However, in an alkaline solution containing 10 mM glucose, the nanoAu/Ti electrode presents much higher anodic current densities and a more negative onset potential (ca. ?0.75 V) for glucose oxidation than a bulk Au electrode. Analysis for Tafel plot of the nanoAu/Ti electrode shows that electro-oxidation of glucose takes place via a one-electron rate-determining step. Results indicate a high and (relatively) stable electrocatalytic activity of the nanoAu/Ti for glucose oxidation.     

Bismuth modified Pd/C as catalysts for hydrogen related reactions

The electrocatalytic activity of bimetallic BiPd catalysts supported on Sibunit carbon towards hydrogen oxidation/evolution reactions (HOR/HER) was studied in a gas diffusion electrode (GDE) setup. Catalysts were synthesized by deposition of Pd on the carbon support, followed by impregnation of Pd/C precursor with Bi(NO₃)₃ solution and reduction in hydrogen. Transmission electron microscopy and local EDX elemental analysis revealed that BiPd/C catalysts contain bimetallic particles with narrow size distribution with maxima at 3.2–4.1 nm. X-ray diffraction evidenced that bimetallic particles are constituted by Pd–Bi solid solution. It was shown that modification of Pd/C by bismuth increases the specific activity of palladium towards HOR/HER by a factor of 3.     

Nanoporous Pt Catalyst Modified by Sn Electrodeposition for Electrochemical Oxidation of Formaldehyde

A nanoporous Pt particles‐modified Ti (nanoPt/Ti) electrode was prepared through a simple hydrothermal method using aqueous H₂PtCl₆ as a precursor and formaldehyde as a reduction agent. The nanoPt/Ti electrode was then modified with limited amounts of tin particles generated by cyclic potential scans in the range of ?0.20 to 0.50 V in a 0.01 mol·L^?1 SnCl₂ solution, to synthesize a Sn‐modified nanoporous Pt catalyst (Sn/nanoPt/Ti). Electroactivity of the nanoPt/Ti and Sn/nanoPt/Ti electrodes towards formaldehyde oxidation in a 0.5 mol·L^?1 H₂SO₄ solution was evaluated by cyclic voltammetry and chronoamperometry. Electrooxidation of formaldehyde on the nanoPt/Ti electrode takes place at a potential of 0.45 V and then presents high anodic current densities due to the large real surface area of the nanoPt/Ti electrode. The formaldehyde oxidation rate is dramatically increased on the Sn/nanoPt/Ti electrode at the most negative potentials, where anodic formaldehyde oxidation is completely suppressed on the nanoPt/Ti electrode. Chronoamperogramms (CA) of the Sn/nanoPt/Ti electrode display stable and large quasi‐steady state current densities at more negative potential steps. Amperometric data obtained at a potential step of 100 mV show a linear dependence of the current density for formaldehyde oxidation upon formaldehyde concentration in the range of 0.003 to 0.1 mol·L^?1 with a sensitivity of 59.29 mA·cm^?2 (mol·L^?1)^?1. A detection limit of 0.506 mmol·L^?1 formaldehyde was found. The superior electroactivity of the Sn/nanoPt/Ti electrode for formaldehyde oxidation can be illustrated by a so‐called bifunctional mechanism which is involved in the oxidation of poisoning adsorbed CO species via the surface reaction with OH adsorbed on neighboring Sn sites.     

Electrocatalytic hydrogenation of 4-chlorophenol on the glassy carbon electrode modified by composite polypyrrole/palladium film

A polypyrrole/palladium composite film was prepared on a glassy carbon electrode by the electrochemical deposition method. The palladium particles were uniformly dispersed on a polypyrrole film that was previously electrodeposited on a glassy carbon electrode. By controlling the polymerization process of pyrrole, a highly porous polypyrrole film was obtained; this kind of structure provided more surface areas for depositing palladium particles. The sizes of Pd particles deposited on the porous polypyrrole film are about 15-30 nm. The X-ray photoelectron spectroscopy results showed there was strong interaction between polypyrrole film and palladium particles. This modified electrode showed excellent current efficiency (49.5%) for electrochemical hydrogenation of 4-chlorophenol and the phenol was the sole product. The potential effect on the dechlorination process was also investigated.