纳米TiO_2-Pt复合膜电极间接电催化氧化甘油为甘油醛的研究

运用电沉积法在纳米TiO2膜上电沉积分散的Pt微粒制成钛基纳米TiO2-Pt复合膜(nano TiO2-Pt)修饰电极,采用循环伏安法和电解氧化法,研究了复合膜电极的电催化活性以及氧化甘油为甘油醛的过程。结果表明,纳米TiO2为锐钛矿型,Pt纳米粒子均匀分散在TiO2多孔膜的表面和内部。复合膜电极在常温常压下对甘油的电化学氧化具有高催化活性和稳定性,在25~30℃下,电流密度为25 m A/cm2时,电流效率达84%,电解产率达89.6%。     

钛丝负载Pt/TiO2电极的制备及其电催化测定化学需氧量研究

采用阳极氧化的方法,在钛丝上制备TiO2纳米管阵列薄膜,用恒电流沉积的方法在TiO2纳米管表面沉积Pt纳米晶,制备了钛丝负载的Pt/TiO2电极.用SEM对电极的形貌进行了表征,纳米管长度在3.5～10 μm之间与氧化电压和氧化时间密切相关,Pt纳米晶均匀沉积在TiO2纳米管表面.用极化曲线、循环伏安曲线、电流-时间曲线对Pt/TiO2电极的电催化性能进行表征.当沉积电流密度大于1.0 mA/cm2时,制备的Pt/TiO2电极的电催化性能显著高于Pt电极.而且,在甲醛等五种有机物溶液中的电催化结果表明,净电流和理论COD之间表现出很好的线性相关性,说明钛丝负载的Pt/TiO2电极可用于电催化快速检测水体中的化学需氧量.     

电合成法制备纳米材料及纳米材料电极上的电催化合成

通过电化学合成前驱体直接水解法制备纳米TiO2 粉体和纳米TiO2 膜电极。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 膜电极对有机合成反应的电催化活性。发现纳米TiO2 膜电极在 0 2～ - 1 2V扫描电位区间有两对氧化还原峰 (峰电位Epc1=- 0 5 6V ,峰电位Epc2 =- 0 95V ,扫描速度 10 0mV·s-1) ,具有异相氧化还原催化行为。电解结果表明 ,纳米TiO2 膜中的Ti(Ⅳ ) /Ti(Ⅲ )氧化还原电对作为媒质 ,异相间接电还原硝基苯为对氨基苯酚 (收率91 6 % ,电流效率 95 2 % )和草酸为乙醛酸 (收率 96 5 % ,电流效率 90 % )。     

甲醇在铂微粒修饰碳纳米管/纳米TiO2-聚苯胺膜电极上的电催化氧化

在0.5mol·L-1硫酸介质中,采用循环伏安的电化学聚合方法,以50mv·s-1的扫描速度,在-0.1～0.9V范围内以碳纳米管/纳米TiO2(CNT/nanoTiO2)电极为基体聚合得到了聚苯胺(PAn)复合膜电极,用循环伏安法研究了CNT/nanoTiO2-PAn-Pt电极在0.5mol·L-1H2SO4溶液中的电化学行为以及对甲醇氧化的电催化行为。结果表明,CNT/nanoTiO2-PAn-Pt电极对甲醇的氧化具有很高的电催化活性,并同时存在PAn的协同催化作用。在Pt载量为0.56mg/cm2时,甲醇氧化峰电流达到152mA/cm2,随着Pt载量的增加,甲醇的氧化峰电流最高可达410mA/cm2。     

纳米TiO2/CNT/ZrO2膜电极的制备及其对2-吡啶甲醛的电催化还原

通过溶胶-凝胶法在Ti表面修饰一层纳米TiO2/CNT/ZrO2复合膜,采用循环伏安和电解合成法研究了复合膜电极在离子液体1-甲基-3-乙基咪唑四氟硼酸盐([EMI]BF4)中对2-吡啶甲醛的电催化还原活性. 结果表明,复合膜为多孔网状结构,粒径约20 nm的TiO2和ZrO2晶粒负载在管径40~60 nm的碳纳米管(CNT)上,纳米TiO2中掺杂ZrO2和CNT后电极催化性能显著改善. 在[EMI]BF4中,控制电位为-1.40 V,用复合膜电极作阴极,Ti(IV)/Ti(III)氧化还原电对作为媒质间接电还原2-吡啶甲醛为2-哌啶甲醇,平均电流效率为85.6%,产率为83%. 反应机理为电化学偶联随后化学催化反应.     

温度及电解液浓度对电沉积法制备Pt/C电极的影响

用电化学沉积法在活性炭表面沉积Pt来制备Pt/C电极。发现改变电沉积温度和电解液中氯铂酸的浓度制备的Pt/C电极,对甲醇及CO氧化的电催化活性有很大不同。沉积条件为80℃、5 mmol.L-1H2PtC l6 0.5 mol.L-1H2SO4与沉积条件为25℃、15 mmol.L-1H2PtC l6 0.5 mol.L-1H2SO4时沉积出的Pt/C电极对甲醇氧化呈现出较高的电催化活性。     

LSMCD法制备纳米(Pb,La)TiO3薄膜

研究了利用液态源雾化化学沉积(LSMCD)法制备纳米(Pb,La)TiO3薄膜的工艺. XRD和SEM分析表明:沉积4次,采用RCA热处理,在Pt/Ti/SiO2/Si基板上成功制备出具有钙钛矿结构的、晶粒粒径约60nm、厚度约180nm的纳米颗粒PLT薄膜.该方法既可以较精确的控制薄膜的化学计量比及掺杂浓度,又可采用控制超声雾化沉积的时间和次数来有效的控制膜厚及晶粒的大小.该工艺的沉积速率约为3nm/min.     

激光加热法制备TiO2和Pt/TiO2纳米颗粒

氧化钛(TiO2)纳米颗粒和金属／氧化钛(M／TiO2)复合纳米颗粒具有优异的物理和化学性质。实验用CO2连续激光直接加热法制备TiO2纳米颗粒和铂/氧化钛(Pt／TiO2)复台纳米颗粒．并用TEM．XRD．和HRTEM等技术对所制备的纳米颗粒进行了表征。用平均粒径为1．0μm的金红石相TiO2粉体压制成的细圆棒料为前驱物．制备的纳米TiO2颗粒呈球形，平均粒径约为30nm．96．2％为锐钛矿相。用TiO2/PtCl2混合物制成的细圆棒料为前驱物，制备的Pt／TiO2纳米复台颗粒平均粒径约为40nm，Pt颗粒被TiO2包裹，并和TiO2分离形成粒径为2～3nm的颗粒．复合粉体内的TiO2有95％以上属锐钛矿相。     

纳米TiO2-Pt修饰电极的制备、性能及应用

采用电化学合成法和电沉积法制备高活性钛基纳米TiO₂-Pt(Ti/nano-TiO₂-Pt)修饰电极,通过循环伏安法研究并比较了钛基纳米TiO₂膜电极、纯Pt电极、Ti/nano-TiO₂-Pt电极在H₂SO₄溶液中的电化学行为以及Ti/nano-TiO₂-Pt电极对Mn²⁺氧化为Mn³⁺的电催化性能.结果表明纳米TiO₂-Pt修饰电极对Mn²⁺的电氧化有高催化活性.Mn²⁺氧化峰电位为1.28 V（vs SCE）,比纯Pt电极负移0.12 V;析氧电位为1.40 V,比纯Pt电极高0.08 V.Ti/nano-TiO₂-Pt修饰电极催化性能优于纯Pt电极和纳米TiO₂膜电极,非均相电解氧化效率可达90%以上.电解得到的Mn³⁺可一步氧化甘油为甘油醛,收率为96%.     

甲醇在碳载纳米Pt电极上的电化学研究

应用循环伏安法制备了nano-Pt/GC修饰电极,优化了铂微粒在电极表面的沉积条件,并用扫描电子显微镜(SEM)和在硫酸中的循环伏安曲线对其进行了表征。结果表明铂微粒较为均匀地分散在玻碳电极表面,粒径约为140nm,电极具有很大的比表面积。循环伏安实验结果表明nano-Pt/GC电极对甲醇电氧化的催化活性明显高于铂片电极,在该修饰电极上甲醇正向扫描和反向扫描时的氧化峰电位分别是0.67V和0.49V,峰电流为61.00mA/cm2和50.50mA/cm2,分别是铂片电极上的3.13倍和3.10倍,有效地提高了金属铂的利用率,铂微粒在电极表面的最佳沉积条件是循环次数为100次和沉积速度为5mV/s。     

乙二醛在纳米TiO2-Pt电极上的电催化氧化

通过电沉积修饰铂微粒制备Ti基纳米TiO₂-Pt（Ti/nano-TiO₂-Pt）修饰电极,采用循环伏安法研究了乙二醛在Ti/nano-TiO₂-Pt上的电催化氧化。结果表明：Ti/nano-TiO₂-Pt修饰电极对乙二醛的氧化呈现较高的电催化活性,可作为乙二醛电氧化合成乙醛酸的高活性催化电极。     

乙醇在SnO2掺杂的TiO2-Pt复合纳米催化剂上的电催化氧化

通过溶胶凝胶和电沉积法制备了SnO₂掺杂的钛基纳米TiO₂-Pt（nano-TiO₂-Pt）复合纳米催化剂。XRD和SEM的研究结果表明,SnO₂的掺杂改变了TiO₂的结构。通过对它们的电化学性质的比较发现,SnO₂的掺杂使nano-TiO₂-Pt复合纳米催化剂的电化学活性表面积增加,常温常压下对乙醇的电化学氧化电位负移,氧化能力明显提高。     

Electrocatalytic activity of Pt nanoparticles deposited on porous TiO2 supports toward methanol oxidation

Porous TiO₂ thin films were prepared on the Si substrate by hydrothermal method, and used as the Pt electrocatalyst support for methanol oxidation study. Well-dispersed Pt nanoparticles with a particle size of 5–7 nm were pulse-electrodeposited on the porous TiO₂ support, which was mainly composed of the anatase phase after an annealing at 600 °C in vacuum. Cyclic voltammetry (CV) and CO stripping measurements showed that the Pt/TiO₂ electrode had a high electrocatalytic activity toward methanol oxidation and an excellent CO tolerance. The excellent electrocatalytic performance of the electrode is ascribed to the synergistic effect of Pt nanoparticles and the porous TiO₂ support on CO oxidation. The strong electronic interaction between Pt and the TiO₂ support may modify CO chemisorption properties on Pt nanoparticles, thereby facilitating CO oxidation on Pt nanoparticles via the bifunctional mechanism and thus improving the electrocatalytic activity of the Pt catalyst toward methanol oxidation.     

铂微粒修饰聚苯胺膜电极对甲酸电催化氧化的研究

采用循环伏安法研究Pt盘电极 (Pt)、铂微粒修饰Pt盘电极 [Pt(Pt) ]和Pt微粒修饰聚苯胺膜电极 [PAN(Pt) ]对甲酸电催化氧化行为的影响 ,比较了它们对甲酸电催化氧化的活性 ,发现PAN(Pt)电极对甲酸电催化氧化的表观电流密度为 3 79× 10 2 mA·cm-2 ,分别比Pt、Pt(Pt)和Pt-PDMA/Pt电极约高 2 35、2 5和 6 3倍。峰电位比Pt PDMA/Pt电极约低 0 16V。     

甲醇在聚苯胺载铂电极上的电催化氧化

用循环伏安法在玻碳电极上电聚合导电高分子聚苯胺用于附载Pt，提高了Pt的分散度。发现甲醇在Pt／PAN／GC电极和Pt／GC电极上均能自发解离出强吸附中间体CO，证实聚苯胺膜的存在有利于提高电极对甲醇的电催化氧化活性，CO在Pt／PAN／GC电极上的氧化峰电流明显高于Pt／GC电极。通过比较甲醇的电催化氧化活性可知，Pt/PAN／GC电极催化氧化甲醇的峰电流为58．68mA/cm^2和50．00mA／cm^2，是Pt／GC电极氧化峰电流的1．6倍和1．7倍。     

Effects of conductive polyaniline (PANI) preparation and platinum electrodeposition on electroactivity of methanol oxidation

A modified galvanostatic method, termed the ‘pulse galvanostatic method’ (PGM) was used to synthesize nanofibular polyaniline (PANI). In contrast to granular PANI prepared by the conventional galvanostatic method (GM), nanofibular PANI has better conductivity and higher specific surface area. The nanofibular PANI electrode modified by Pt microparticles, at the same Pt loading, exhibits a considerably higher electrocatalytic activity on the methanol oxidation than that of the granular PANI electrode modified by Pt microparticles. Furthermore, the PGM method can be used as a good method for Pt microparticle electrodeposition. The composite electrode composed of PANI and Pt microparticles has the best electrocatalytic activity in the experimental range. The effects of Pt loading and methanol concentration, on the electrocatalytic activity for methanol oxidation have also been researched.     

Electrocatalytic oxidation of methanol on Cu modified polyaniline electrode in alkaline medium

Electrolytically deposited Cu on polyaniline film covered Pt substrate (Cu/PANI/Pt) is used as anode for the electrooxidation of methanol in alkaline medium. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry, impedance spectroscopy, chronomethods, rotating disc voltammetry and polarization studies. The morphology and composition of the modified film were obtained using SEM and EDAX techniques. The electrooxidation of methanol in NaOH is found to be more efficient on Cu/PANI/Pt than on bare Cu (Cu), electrodeposited Cu on Cu (Cu/Cu) and electrodeposited Cu on Pt (Cu/Pt) substrates. Partial chemical displacement of dispersed Cu on PANI with Pt or Pd further improved its performance towards methanol oxidation.     

Activity of a novel titanium-supported bimetallic PtSn/Ti electrode for electrocatalytic oxidation of formic acid and methanol

Bimetallic platinum–tin nanoparticles were co-deposited on a titanium surface using a simple one step hydrothermal method process. The electrochemical catalytic activity of this titanium-supported nanoPtSn/Ti electrode towards the oxidation of formic acid and methanol in 0.5 M H₂SO₄ was evaluated by voltammetric techniques, chronoamperometric responses and electrochemical impedance spectra (EIS). According to the cyclic voltammograms of the oxidation of both formic acid and methanol, the nanoPtSn/Ti presents high anodic current densities and low onset potentials. Potential-time transient measurements show that the nanoPtSn/Ti exhibits high steady-state current densities for the oxidation of both formic acid and methanol. The EIS data indicate that the nanoPtSn/Ti presents very low electrochemical impedance values, showing that for the oxidation of both formic acid and methanol, low charge transfer resistances are present on the nanoPtSn/Ti catalyst. This confirms the high electrocatalytic activity of the nanoPtSn/Ti for the formic acid and methanol oxidation.     

用磷钼酸修饰甲醇燃料电池的铂电极

近年来以杂多化合物为基础的催化体系受到广泛的关注.为了研究杂多酸与铂电极对甲醇电催化氧化的协同效应,通过循环伏安扫描法制备了磷钼酸（H3PMo12O40）修饰铂电极.通过循环伏安和计时电流法研究了该修饰电极对甲醇氧化的电催化活性和抗中间产物的毒化作用,并比较了该修饰电极与其单酸盐（Na2MoO4）修饰铂电极的性能,测试结果表明：磷钼酸修饰铂电极能够提高对甲醇氧化反应的催化活性,基本上同其单酸盐Na2MoO4修饰铂电极的催化活性相当,并且这种促进作用主要是由Mo原子价态变化引起的.同时计时电流曲线测试结果表明,该修饰电极具有一定的抗毒化作用,但不如钼酸钠好.