Au/PAni/GC电极的制备及对甲醛的电催化氧化研究

应用循环伏安、恒电位阶跃等方法研究了在苯胺修饰的玻碳电极（PAni/GC） 表面金颗粒的电化学沉积及不同的制备方法对甲醛氧化电催化活性的影响。研究表 明,在PAni/GC电极表面,金的电沉积在初始阶段遵循扩散控制瞬时成核三维成长 模式。在碱性介质中,电解沉积法制备的电极比循环伏安法制备的电极对甲醛的催 化氧化有更高的催化电流。但是,在循环伏安法制备的电极上甲醛的氧化可以在很 负的电极电位下发生。     

Pt/PMo12/PEDOT/GC电极的制备及其甲醇电氧化性能

将磷钼酸(PMo12)修饰到电化学聚合制得的聚3,4-乙烯二氧噻吩(PEDOT)(PEDOT/GC)膜表面(PMo12/PEDOT/GC),随后电沉积Pt得Pt/PMo12/PEDOT/GC电极.研究了PMo12和PEDOT对电极氧化甲醇性能的影响.结果表明,PMo12改变了电极上负载Pt的形态和结构,导致Pt纳米结构边缘产生尖锐的刺状结构.Pt/PMo12/PEDOT/GC和Pt/PEDOT/GC电极有较好的甲醇氧化电催化活性,而前者尤佳.PEDOT不仅提高甲醇氧化的电流,还使甲醇的起始氧化电位负移.进一步修饰PMo12后,可明显增大甲醇氧化的电流.     

Zr掺杂对PdO/Ce_(1-x)Pd_xO_(2-δ)催化剂CO和CH_4催化氧化的影响（英文）

采用溶液燃烧法制备出PdO/Ce_(1-x)Pd_xO_(2-δ)和PdO/Ce_(1-x)Pd_xO_(2-δ)(Pd O/CPZ)催化剂,通过硝酸处理去除催化剂表面的Pd O物种得到对应的Ce_(1-x)Pd_xO_(2-δ)(CP)和Ce_(1-x)Pd_xO_(2-δ)(CPZ)催化剂。考究四种催化剂(Pd O/CP、Pd O/CPZ、CP、CPZ)对CO和CH_4的氧化活性,并计算得出表面Pd O和Pdn+物种的转化频率(TOF)。结果表明Zr的添加对Pd O催化剂上CO和CH_4的催化氧化活性具有不同的影响。Zr的添加对Pd O/CPZ和CPZ催化剂的CO催化活性具有明显的促进作用,前者归因于PdO/CPZ催化剂表面生成了更小颗粒的Pd O粒子,后者归因于CPZ催化剂中含有更多的氧空位。对于CH_4的催化氧化,Pd~(n+)物种起到关键的作用。由于Zr的掺杂导致Ce O2的晶格中Pd物种的含量减少,致使PdO/CPZ催化剂和CPZ催化剂对CH_4氧化活性的降低。     

不同介质对Pt/GC电极制备及其性能的影响

应用循环伏安法(CV),扫描电子显微镜(SEM)和电化学原位红外反射光谱(in situFTIRS)研究了不同介质对碳载铂纳米薄膜电极(Pt/GC)的表面结构以及该薄膜电极对甲酸电催化氧化性能的影响.结果表明,使用不同介质的镀铂溶液,均可电沉积出分布较为均匀的Pt粒子,但其尺寸与形貌却相差很大.当以H2SO4作介质,由循环伏安法于玻碳电极上电沉积Pt得到的(Pt/GC1)电极,其Pt粒子粒径约100~200 nm;而在HClO4介质得到的(Pt/GC2)电极,则含有两种Pt微晶:其一是立方体形,粒径约200 nm,其二为菜花状,粒径约400 nm.电化学循环伏安和原位红外反射光谱测试指明,不同介质制备的Pt/GC电极对甲酸的电催化氧化均表现出与本体铂电极(Pt)相类似的特性,即可通过活性中间体或毒性中间体将甲酸氧化至CO2,但不同结构的Pt/GC电极具有不同的电催化活性.进一步以Sb或Pb修饰Pt/GC电极,不仅可以有效地抑制毒性中间体CO的生成,而且还能显著提高其电催化活性.比较本文研究的7种电极,其电催化活性顺序依次为:Sb-Pt/GC2>Pb-Pt/GC2>Pb-Pt/GC1>Sb-Pt/GC1>Pt/GC2>Pt/GC1>Pt.     

自组装纳米金膜上铂微/纳结构电催化剂的制备及性能

基于纳米金(AuNP)表面基团的静电自组装作用制备了多层有序的纳米金超薄膜. 研究了自组装纳米金超薄膜上铂微/纳结构催化剂(Pt/AuNP)的制备过程. 考察了沉积电位和沉积时间对甲酸电氧化活性的影响, 确定了最佳沉积电位为0 V, 最佳沉积时间为600 s. 同时对比考察了Pt/AuNP/PE/GCE, AuNP/PE/GCE和纯Pt电极在0.1 mol/L H2SO4介质中对甲酸电氧化活性以及载体对沉积物形态和甲酸氧化活性的影响. 研究结果表明, 纳米金组装体对铂的电沉积有明显的促进作用; Pt/AuNP/PE/GCE对甲酸的电氧化有很好的电催化性能.     

离子注入Pt的玻碳电极上甲酸和甲醛的电氧化

制备了离子注入Pt的玻碳电极(Pt/GC),注入剂量为5×10¹⁷ion/cm²,此电极的表面组成和各元素的浓度-深度分布用AES测量,注入Pt的价态用XPS测量.在0.5mol/LHClO₄溶液中,用Pt/GC电极和纯Pt电极研究了甲酸的电氧化行为,并在五种不同种类的电解质溶液中研究了甲醛的电氧化行为.结果表明,Pt/GC电极对甲酸和甲醛的电催化性能按真实表面积计算优于纯Pt电极.这可能与离子注入Pt过程中形成纳米团簇有关.此外,在同一电极上,甲醛在不同种类的电解质溶液中产生不同的氧化电流.说明阴离子对甲醛的电氧化过程有明显影响     

金属化聚邻甲苯胺膜修饰电极的性能研究

在聚邻甲苯胺 (POT)膜修饰电极上用电化学法沉积Pt微粒 ,由SEM与XRD表征其表面形态与晶面取向 ,同时研究异丙醇在金属化POT膜电极上的氧化行为 .结果表明 ,Pt在POT膜上的沉积呈现晶面择优取向的现象 ,况且POT质子掺杂后 ,由于电化学活性增强 ,影响了沉积铂微粒的尺寸和粒径分布 .异丙醇的电氧化可发生在POT的电化学活性区 ,当电位大于 0 .70V(SCE)时 ,POT不再呈氧化还原活性 ,异丙醇的电氧化主要在铂微粒上进行 .聚合物不仅作为铂微粒的载体而且自身参加反应 ,这种微异相催化体系需用新的模型描述     

Ni/PdO/RuO_2复合型活性阴极的制备与表征

采用热分解氧化法,在Ni基体上制备以PdO为中间层、RuO2为活性层的Ni/PdO/RuO2复合型活性阴极,并通过XPS、XRD、能量色散X荧光(EDXRF)、SEM、极化曲线、循环伏安法和交流阻抗谱等表征其组成、结构与电化学性能。结果表明,Pd和Ru分别以PdO和RuO2的形式存在于Ni/PdO/RuO2复合型活性阴极中,其含量分别为1.25wt%和1.71wt%;在363K、11mol·L-1NaOH溶液、3kA·m-2电流密度下,Ni/PdO/RuO2复合型活性阴极的析氢过电位比Ni电极和Ni/RuO2电极分别低371和125mV;循环伏安法循环72h后,该复合型活性阴极双电层电容值减小30.6%,比Ni/RuO2电极表层结构更稳定;Ni/PdO/RuO2复合型活性阴极的表面粗糙度大且无明显的裂纹存在,与纯镍电极相比,该复合型活性阴极比表面积增加了31.12倍。     

Pd/石墨烯复合材料的制备及电催化甲酸和甲醇性能研究

通过电解高纯石墨棒的方法制备氧化石墨,将氧化石墨在超纯水中超声,形成稳定的氧化石墨烯分散液。以氧化石墨烯分散液和氯化钯作为前驱体,采用一步电沉积法制备Pd/石墨烯纳米复合材料。用扫描电子显微镜(SEM)、X射线衍射仪(XRD)及紫外可见分光光度计(UV-vis)对物质的表面形貌及物相组成进行表征分析。用循环伏安法(CV)和计时电流法(CA)研究了Pd/石墨烯催化剂对甲酸和甲醇的电催化氧化活性。结果表明:与纳米钯修饰电极相比,Pd/石墨烯修饰电极对甲酸及甲醇的电催化氧化活性有了极大的提高。     

铁氰化钆修饰电极的制备及表征

应用电化学循环扫描法于玻碳电极表面沉积并形成铁氰化钆修饰电极(GdHCF/GC),扫描电镜(SEM)显示,有两种大小和外形明显不同的颗粒状GdHCF附着在电极表面.红外光谱表明,GdCHF的C≡N弯曲振动吸收峰出现在2062.5 cm-1处.循环伏安法测试表明,在0.2 mol/L NaC l溶液中,GdHCF/GC电极出现两对氧化还原峰,扫速为20 mV/s时,其氧化还原峰的式量电位分别为E0’(I)=192.5 mV和E0’(II)=338.5 mV.研究了不同支持电解质对GdHCF/GC电极电化学性能的影响,GdHCF对Na+离子有优先选择性.     

吸附原子电催化机理的研究——铂单晶(100)晶面上Pb、Cd吸附原子在甲酸电氧化中的助催化特性

In this work a modified adsorption method was used to form firstly a saturated Cd or Pb adlayer on platinum single crystal (100) surface, then its surface structure, the electrochemical stability and the desorption-readsorption CV properties were studied. The HCOOH oxidation has been used as a probe to determine the electrocatalytic propertics of Pt (100) with different surface concentration of Cd or Pb adatoms. The results show that Cd adatoms on Pt(100) inhibit both HCOOH dissociation adsorption (to form poisoning intermediates) and HCOOH oxidation via the reactive intermediate, and that Pb adatoms on Pt(100) inhibit only HCOOH disociation adsorption but catalyse HCOOH oxidation via the reactive intermediate, in this case the more Pb adatoms on Pt(100), the higher te catalytic effect. The highest enhanced catalytic effet has been found with the saturated Pb adlayer on Pt(100) (the coverage of Pb, calibrated by hydrogen adsorption, is then equal to 1.0), i.e. with a surface structure of C(2×2)-bridged Pb. The difference of influence to the hydrogen adsorption-desorption process and the different catalytic effect on HCOOH oxidation of Cd and Pb adatoms on Pt(100) were attributed to the intrinsic properties of Cd and Pd elements and also to their interaction with Pt(100). This results indicate that the electrocatalytic mechanism of Cd and Pb adatom on Pt(100) depends on the geometrical surface structure effect and, more importantly, on the electro structure effect during the interaction of adatoms with Pt(100) surface atoms.     

甲酸在钯微粒修饰聚苯胺电极上氧化的协同效应研究

Electrochemical oxidation of formic acid on PAN(Pd) electrode has been studied using conventional electrochemical techniques and the electrochemical in-situ FTIR. The process of electrochemical oxidation of PAN(Pd) electorde has been put forward. The kinetic parameters of different thickness of PAN film such as diffusion coefficient (D0) and reaction rate constant(k0) have been calculated. Furthermore, the causes of the difference between PAN(Pd) and pure Pd(or Pt) electrodes as well as the high electrocatalytic activation of PAN(Pd) electrode for oxidation of fomic acid have also been discussed. The high catalytic activation of PAN(Pd) electrode for oxidation of formic acid probably comes from the synergistic effect of the subcatalytic interaction of PAN and the catalytic interaction of the palladium microparticles.     

Theoretical elucidation of the competitive electro-oxidation mechanisms of formic acid on Pt(111)

The mechanisms of formic acid (HCOOH) oxidation on Pt(111) under electrochemical conditions have been studied using density functional theory and then compared with the analogous gas-phase reaction. Results show that HCOOH oxidation under a water-covered surface behaves substantially differently than in the gas phase or using a solvation model involving only a few water molecules. Using these models, we evaluated the detailed reaction process, including energies and geometric structures of intermediates and transition states under the influence of different solvation models and electrode potentials. Our calculations indicate that this potential-dependent electrochemical oxidation proceeds via a multipath mechanism (involving both the adsorbed HCOOH and HCOO intermediates), a result succinctly rationalizing conflicting experimental observations. Moreover, this study highlights how subtle changes in electrochemical reaction environments can influence (electro)catalysis.     

铂钯修饰聚N-乙酰苯胺膜电极对甲酸的电催化氧化

由电化学方法在石墨电极表面制备了规整多孔的纳米结构聚N-乙酰苯胺(PAANI)膜,并以其为载体制备了Pt-Pd/PAANI/C二元金属微粒修饰的聚合物复合膜电极.SEM和XRD研究结果表明,Pt、Pd微粒在PAANI膜中均匀分散,有效地改善了催化剂中贵金属的分散度和电极的结构.在0.5mol/L H2SO4+0.5mol/LHCOOH溶液中的循环伏安结果表明,Pt-Pd/PAANI/C电极在酸性溶液中电催化氧化甲酸的性能明显优于直接电沉积的Pt-Pd/C电极,且表现出较高的稳定性.     

Pd/Pt二元合金电极的制备及氧还原性能

本文利用欠电位沉积亚单层的Cu及Pt置换取代Cu的方法, 制备了具有不同表面元素组成的Pd/Pt二元合金电极(用Pd/Ptx表示, x指欠电位沉积Cu-Pt置换取代Cu过程的次数),并对其表面元素组成、氧还原性能进行了表征. 在控制欠电位沉积Cu的下限电位恒定(0.34 V)的前提下, 表面Pt/Pd的元素组成比通过重复欠电位沉积Cu及Pt置换取代Cu的次数(1~5次)来可控地调变. 光电子能谱(XPS) 以及红外光谱实验表明,Pd/Ptx电极表层区的Pt：Pd元素组成比随着Pt沉积次数增加而增加, 对Pd/Pt4电极, 在电极表层区约2~3 nm内的Pt/Pd的原子比大约是1:4,而最表层裸露Pd原子的比例仍在20%以上。循环伏安结果显示, 随着Pt沉积次数的增加(1-5次), Pd/Ptx电极表面越不易被氧化。氧还原测试结果显示随着Pt沉积次数的增加(1~4次), Pd/Ptx二元金属电极的氧还原活性依次增加, 经过第3次沉积后其氧还原活性已优于纯Pt,而经4次以上沉积,其氧还原活性基本不变。在其它反应条件相同条件的前提下, Pd/Pt4电极上氧还原的半波电位与纯Pt相比右移约25 mV。结合本文与文献的实验结果,我们初步认为Pd/Ptx二元金属体系氧还原性能改善主要源自表层Pd原子导致其邻近的Pt原子上含氧物种吸附能的降低.     

Pt电极上Sb，S吸附原子对正丁醇电催化氧化性能的影响

运用电化学循环伏安和石英晶体微天平研究了0.1 mol/L H2SO4 溶液中正丁醇（1-BL）在Pt电极和以Sb，S吸附原子修饰的Pt（Pt/Sbad和Pt/Sad）电极上电催化氧化过程。从电极表面质量变化表明正丁醇的氧化与电极表面氧物种有着极其密切的关系。Pt电极表面Sb吸附原子能在较低的电位下吸附氧，可显著提高正丁醇电催化氧化活性。与Pt电极相比较，Sb吸附原子修饰的Pt电极使正丁醇氧化的峰电位负移了0.33 V，峰电流增大了近一倍。相反，Pt电极表面S吸附原子的氧化会消耗表面氧物种，抑制了正丁醇的电氧化。本文从表面质量变化提供了吸附原子电催化作用的新数据。     

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.     

Fabrication of High‐aspect Ratio (HAR) Palladium Nanorod‐modified Electrodes for Raman Spectroelectrochemical Studies of Thiolate Desorption from HAR Nanomaterials

We describe a method to fabricate electrodes modified with high‐aspect ratio (HAR) palladium (Pd) nanorods derived from the electrochemical reduction of Pd salts in polycarbonate track‐etched membranes. The HAR Pd nanorod‐modified electrode platform enables direct spectroscopic observation of electrochemical processes particular to HAR forms of nano‐Pd using Raman spectroelectrochemistry. In the present study, we use this platform to observe an anomalous mechanism of oxidative electrochemical desorption of the probe molecule benzenethiol (BT) from the HAR Pd surface. At HAR Pd, the Pd?S bond between the Pd nanorods and BT severs upon oxidation of the Pd surface, whereas on the surface of spherical nano‐Pd, the C?S bond in BT is broken, as is more typically observed for sulfur‐containing organic molecules adsorbed to Pd surfaces. Using this probe reaction, we demonstrate the suitability of this HAR nanorod‐modified electrode platform for the investigation of anomalous electrochemical phenomena observed at HAR Pd for reactions that involve adsorbed intermediates in general – including not only adsorbed sulfur – but in principle also for the electrochemical oxidation of alternative fuels such as ethanol and methanol.