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     

FeTSPc对Pt电极对氧还原的电催化性能和耐甲醇性能的影响

为了解决直接甲醇燃料电池(DMFC)中“甲醇渗透”的问题, 用大环化合物四磺酸基酞菁铁(FeTSPc)对光滑铂(Pt)电极进行修饰, 发现FeTSPc修饰的Pt电极(Pt-FeTSPc)和Pt电极对氧还原的电催化活性相近, 而Pt-FeTSPc电极对甲醇氧化的电催化活性比Pt电极下降30.9%, 表明Pt-FeTSPc电极有较好的耐甲醇能力.     

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.     

甲醇在铂微粒修饰的聚硫堇电极上的电催化氧化

利用电化学循环伏安和现场ＦＴＩＲ反射光谱等技术研究了甲醇在铂微粒修饰的聚硫堇电极上的电催化氧化。结果表明，循环伏安法制备的铂微粒均匀分散于聚合物膜上，其粒径大小约为３０－１３０ｎｍ；复合修饰电极对甲醇电化学氧化呈现了较高的催化活性，其催化活性的大小依赖于Ｐｔ载量。现场ＦＴＩＲ光谱实验揭示了线性吸附的ＣＯ物种是甲醇在复合电极上氧化的唯一中间体，这种吸附的ＣＯ物种在复合修饰电极上更容易被氧化为最终产物     

多层聚吡咯-铂复合膜电极的甲醇电催化氧化

应用循环伏安法电沉积多层聚吡咯-铂复合膜电极,研究该电极的甲醇电催化氧化性能.循环伏安和计时安培法测试表明,该复合膜电极具有更好的甲醇电催化活性和抗毒性.铂量增加,电极反应控制步骤将由CO氧化转化为甲醇的吸附脱氢.     

Sm3+对甲醇电化学氧化反应的助催化作用

分别以相同面积的光滑Pt电极和吸附了Sm3+的铂电极作为工作电极,在酸性介质中采用循环伏安法对甲醇氧化进行测定.结果表明,吸附了Sm3+的Pt电极上产生了更大的氧化电流,表明Sm3+的加入对甲醇的电催化氧化起到了促进作用.这一研究结果在直接甲醇燃料电池(DMFC)阳极催化剂研制方面具有较大的应用潜力.     

聚邻苯二胺/铂复合电极的制备及其电催化研究

利用原位聚合原位还原复合法制备了聚邻苯二胺(PoPD)/铂(Pt)复合电极。通过扫描电镜(SEM)、x射线能谱(XRD)、傅立叶变换红外光谱(FTIR)、和交流阻抗(EIS)对其形貌、组成元素和结构等进行了表征。研究了Poly(O-Phenylenediamine)/Platinum电极对甲醇的电催化行为,发现该复合电极对甲醇有良好的电催化性能。与裸铂电极相比,氧化电流高出约4.5倍。通过循环伏安法和计时电量法测定了修饰电极在甲醇溶液中的动力学参数,测得电子转移数为1,扩散系数为8.5687×10-7㎝2/s。     

Pt及其修饰电极上甲醇吸附和氧化的CV和EQCM研究

运用电化学循环伏安和石英晶体微天平 (EQCM )研究了 0 .1mol·L- 1H2 SO4 溶液中甲醇在Pt电极和以Sb ,S不可逆吸附原子修饰的Pt(Pt/Sbad和Pt/Sad)电极上的吸附和氧化过程 .结果表明甲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 ,可显著提高甲醇电催化氧化活性 .与Pt电极相比较 ,Sb吸附原子修饰的Pt电极使甲醇氧化的峰电位负移了 0 .13V .相反 ,Pt电极表面S吸附原子的氧化会消耗表面氧物种 ,抑制了甲醇的电氧化 .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     

分子印刷技术铂微粒修饰电极及甲醇的电催化氧化

利用分子印刷技术(Molecular Imprinting Technology，MIT)，将铂微粒沉积到谷胱甘肽自组装膜的针孔上，并用循环伏安法研究了甲醇在该电极上的电催化氧化行为。实验结果表明，该电极对甲醇电化学氧化呈现出较高的催化活性，活性高低与载铂量、溶液pH值及电极表面铂微粒所处的微环境有关。     

磷钼酸修饰的铂电极对二甲醚氧化的电催化作用

利用循环伏安扫描法制备了磷钼酸(H3PMo12O40)修饰的铂电极.在制备修饰电极时,随着扫描次数的增加,磷钼酸的氧化还原峰电流增大,但最终获得稳定的重现性好的磷钼酸修饰的铂电极.通过循环伏安法研究了该修饰电极对二甲醚氧化的电催化反应.结果表明,与未修饰的铂电极相比,磷钼酸修饰的铂电极电催化氧化二甲醚的起始氧化电位负移50 mV,氧化峰电位负移35 mV,氧化峰电流密度提高了1.86倍,这表明修饰电极的电催化活性有了很大的提高.同时,电位负扫时,二甲醚在425 mV(vsSCE)处出现氧化峰,表明二甲醚在修饰电极上的电氧化机理可能发生了改变.实验还发现,制备修饰电极时,降低扫速会提高还原物质杂多蓝的吸附量,但过多的修饰物质会降低铂的活性位数目,反而降低了对二甲醚氧化的电催化作用.     

球型Pt微粒电极的构建及其对甲醇电氧化的研究

以镍铬合金为基体,在其表面电化学沉积制备了Pt微粒电极,用扫描电子显微镜（SEM）对电极的表面形貌进行了表征,电化学方法考察了电极的电化学性能和甲醇在该电极上的电催化行为．结果表明镍铬合金表面沉积的球型Pt微粒电极对甲醇的电氧化具有良好的催化活性,相同实验条件下,该电极的催化活性比纯Pt电极高30倍．该电极对甲醇的电氧化显示出较高的催化性能．     

Electrooxidation of methanol on upd-Ru and upd-Sn modified Pt electrodes

The electrochemical oxidation of methanol has been investigated on underpotentially deposited-ruthenium-modified platinum electrode (upd-Ru/Pt) and on underpotentially deposited-tin-modified platinum electrode (upd-Sn/Pt). The submonolayers of upd-Ru and upd-Sn on a Pt electrode increased the rate of methanol electrooxidation several times as large as that on a pure Pt electrode. The best performance for methanol electrooxidation was obtained on a ternary platinum based catalyst modified by upd-Ru and upd-Sn simultaneously. The influence of the submonolayers of upd-Ru adatoms and upd-Sn adatoms on the oxidation of methanol in acid has been investigated. The effect of Ru on methanol electrooxidation lies on the distribution of Ru adatoms on a Pt surface. It has been shown that as long as the amount of upd-Ru deposits were controlled in a proper range, upd-Ru deposits would enhance the methanol oxidation obtained on a Pt electrode at whichever deposition potential the upd-Ru deposits were obtained. The effects of tin are sensible to the potential range. The enhancement effect of upd-Sn adatoms for the oxidation of methanol will disappear as the electrode potential is beyond a certain value. It is speculated that there exists a synergetic effect on the Pt electrode as adatoms Ru and Sn participate simultaneously in the methanol oxidation.     

Methanol electrooxidation in alkaline solutions on platinum-based electrodes: Classical and dynamical approach

The electrochemical oxidation of methanol has been carefully studied due to its application in fuel cells. In this work electrooxidation of methanol was investigated on bare platinum electrode, the platinum electrode covered with Nafion and platinum supported on zeolite 13X. Along with classical electrochemical methods, attractor reconstruction was used to make rough distinction among possible reaction mechanisms on different forms of Pt. The obtained transient voltammogram records were used to calculate apparent rate constants for methanol oxidation limiting steps in transient period. All samples contributed to methanol oxidation by basically same reaction mechanism, but with significantly different apparent rate constants.     

磷钼酸对直接甲醇燃料电池阴极氧还原的促进作用

以磷钼酸(H₄PMo₁₂O₄0·xH₂O,PMo₁₂)为直接甲醇燃料电池(DMFC)阴极添加剂,制备了Pt-PMo₁₂/C复合催化剂.电化学测试表明,该添加剂对于DMFC阴极氧还原具有明显的促进作用,与常规的Pt/C催化剂相比,相同载量下极限扩散电流提高了56.3%.在单电池性能测试中,这种促进作用使电池的最大输出功率提高了28%.     

Performance evaluation of nickel as anode catalyst for DMFC in acidic and alkaline medium

Direct methanol fuel cell (DMFC) research is highly focused due to its high energy density, portability and inexpensive. In the present study conventional platinum catalyst used for methanol oxidation is being replaced with nickel catalyst supported over nickel mesh. The electrode is synthesized by single step electro deposition technique. Synthesized electrode was characterized by SEM, EDAX and AFM techniques to know the surface morphology, composition and thickness of the catalyst respectively. The electro catalytic behavior of the nickel for methanol oxidation was evaluated using cyclic voltammetry technique. As the DMFC is compatible with both the acidic and alkaline electrolytes the working of the nickel mesh electrode is analyzed in both media. The results showed maximum current density of 0.025 and 0.030 A/cm² in alkaline and acidic medium respectively with less potential around 0.4 and 0.2 V. The other parameters such as varying the concentration of methanol, electrolyte medium, scan rate and thickness of the catalytic layer were analyzed and optimized.     

Platinum nanoparticles coated by graphene layers: A low-metal loading catalyst for methanol oxidation in alkaline media

Platinum catalysts play a major role in the large scale commercialization of direct methanol fuel cells(DMFC). Here, we present a procedure to create a nanostructural graphene-platinum(Gr Pt) composite containing a small amount(5.3 wt%) of platinum nanoparticles coated with at least four layers of graphene. The composite, as Gr Pt ink, was deposited on a glassy carbon electrode and its electrocatalytic activity in a methanol oxidation reaction(MOR) was evaluated in a 1 M CH_3 OH/1 M Na OH solution. The results indicated an enhanced catalytic performance of Gr Pt towards MOR in alkaline media compared with the Pt/C material. Electron energy-loss spectroscopy and X-ray photoelectron spectroscopy(recorded before and after the electrochemical assays) were employed to analyze the changes in the chemical composition of the nanomaterial and to explain the transformations that took place at the electrode surface.Our findings suggest that growing of graphene on platinum nanoparticles improve the catalytic performance of platinum-graphene composites towards MOR in alkaline media.     

Electrocatalytic oxidation of methanol onto platinum particles decorated nanostructured poly (1,5-diaminonaphthalene) film

In this work, platinum particles decorated nanostructured poly (1,5-diaminonaphthalene) modified glassy carbon electrode (Pt/Nano-PDAN/MGCE) is prepared. The composite catalysts are characterized by scanning electron microscopy, energy dispersive spectroscopy, and electrochemical methods. The electrochemical methanol oxidation reaction is studied at the surface of this modified electrode. At same Pt loading, the Pt/Nano-PDAN/MGCE can act as higher efficient catalyst for methanol oxidation than that Pt/MGCE. Then, the influence of some parameters such as potential scan rates, switching potential, and methanol concentration on its oxidation as well as long-term stability of the modified electrode have studied by electrochemical methods. Also, ability of the modified electrode toward electrocatalytic oxidation of formaldehyde as an intermediate in methanol oxidation has been investigated.     

一种新型直接甲醇燃料电池阳极添加剂的电化学研究

将磷钼酸(H₄PMo₁₂O₄₀·xH₂O,PMo₁₂)作为一种添加剂,制备了直接甲醇燃料电池阳极Pt-Ru/C-PMo₁₂复合催化剂,并对甲醇在含有此复合催化剂的阳极上的氧化进行了电化学研究.测试表明该添加剂降低了甲醇及其电氧化中间产物转化的活化能,改善了电极内部的质子传输状况,对甲醇的电化学氧化过程具有明显的促进作用,该复合催化剂与常规的Pt-Ru/C催化剂相比,甲醇的阳极氧化电流提高了46%.添加剂的这一效应可能与磷钼酸的Keggin结构有关.     

操作条件对DMFC阴极电化学阻抗谱参数的影响

通过降低阴极催化剂载量强化了阴极氧还原反应的电化学极化, 测量了不同操作条件下直接甲醇燃料电池(DMFC)的极化曲线和交流阻抗谱,并提出了改进的等效电路模型LR(CR)(QR(LR))用以分析温度、空气流量和甲醇流量对DMFC阴极电化学反应和传质极化过程的影响. 研究结果表明, 提高工作温度会导致更多的甲醇渗透到阴极, 加大阴极氧气还原反应的电荷转移电阻; 只有采用大的空气流量,才会有效地防止水淹, 加大氧气向催化剂层的传质, 促进阴极反应的进行; 适当提高甲醇的流量可以促进阳极和阴极电化学反应的进行, 但是过高的甲醇流速可能会降低电极表面的温度, 加剧甲醇的渗透.     

High dispersion and electrocatalytic properties of platinum nanoparticles on graphitic carbon nanofibers (GCNFs)

Highly dispersed platinum nanoparticles were electrodeposited on graphitic carbon nanofibers (GCNFs) by cyclic voltammetry (CV) in 7.7 mM H2PtCl6+0.5 M HCl aqueous solutions. The graphitic carbon nanofibers (GCNFs) used in this paper were grown directly on a graphite disk by chemical vapor deposition (CVD). The micrographs and element composition of Pt/GCNFs/graphite electrode were characterized by scanning electron microscopy (SEM) and electron diffraction spectroscopy (EDS). The electrocatalytic properties of Pt/GCNFs/graphite electrode for methanol oxidation have been investigated by CV and excellent electrocatalytic activity can be observed even at very low platinum loading (md=8.79 microg cm(-2)). The highest mass activity (MA) for methanol oxidation reaches 323 Ag(-1) when Pt/GCNFs/graphite electrode was cycled at a sweep rate of 50 mVs(-1) by CV in 2 M CH3OH+1 M H2SO4 aqueous solutions. This may be attributed to the small particle size and high dispersion of platinum particles coated on GCNFs and shows good potential application in direct methanol fuel cell (DMFC). Additionally, the long-term cycling stability of platinum catalysts was also investigated.