Hydrothermal Syntheses of NiO−GO Nanocomposite on 3D Nickel Foam as a Support for Pt Nanoparticles and its Superior Electrocatalytic Activity towards Methanol Oxidation

In this project, Pt/NiO?GO nanocatalyst is grown on nickel foam (NF) and, its catalytic activity towards electrochemical oxidation of methanol in acidic media is studied. The first step is devoted to the synthesis of NiO?GO support by a hydrothermal method. Then Pt nanoparticles (～34.3 nm) are electrodeposited on this supporting material. Hydrothermal and electrochemical deposition conditions are optimized. Surface of modified NF was inspected for physical characterization and Chemical composition by some techniques such as field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectra (EDS), and X‐ray diffraction (XRD). In the electrochemical section, the catalytic performance of Pt/NiO?GO/NF towards methanol oxidation is investigated by cyclic voltammetry and chronoamperometry measurements. The electrochemical impedance spectroscopy (EIS) is elected to deliberate charge transfer resistance on the catalyst surface. Mass activity, electrochemical surface area (ECSA) and durability of prepared catalysts are compared with commercial Pt/C. Deliberations prove the superiority of Pt/NiO?GO/NF towards methanol oxidation in acidic media. The Superior quality of synthesized nanocatalyst that is attributed to the synergetic effect of the NiO?GO support material and Pt nanoparticles, indicate that Pt/NiO?GO/NF can be successfully used as the anode in the direct methanol fuel cell (DMFC).     

高分散直接甲醇燃料电池Pt／C阴极电催化剂的制备过程机理与表征

 通过调变的多元醇法制备了40％Pt／C直接甲醇燃料电池阴极电催化剂，应用透射电镜（TEM）及X射线衍射（XRD）方法表征催化剂．结果表明，由该制备方法可得到高分散，金属粒子粒径分布窄的高载量贵金属催化剂．TEM统计结果表明，调变多元醇法制备的40％Pt／C催化剂的金属粒子平均粒径约为2．9nm．直接甲醇燃料电池单池性能测试表明，该方法制得的40％Pt／C的电催化氧还原能力比同型商品催化剂更好．另外，利用UV－Vis光谱研究了催化剂的制备过程．结果表明，在调变的多元醇法中，Pt4＋的还原是一步完成的．     

直接甲醇燃料电池阴极催化剂的研究进展

直接甲醇燃料电池阴极催化剂的研究进展;直接甲醇燃料电池;阴极催化剂;氧还原;耐甲醇     

Pt/RuO2/CNTs纳米催化剂中RuO2含量对甲醇电催化氧化性能的影响

制备了一种新的甲醇直接燃料电池Pt/RuO2/CNTs阳极催化剂,在相同Pt负载量下,其甲醇电催化氧化活性是Pt/CNTs的3倍.采用循环伏安法研究发现Pt/RuO2/CNTs纳米催化剂中RuO2含量对甲醇电催化氧化活性有明显影响,当Pt和RuO2在碳纳米管上含量分别为15%和9.5%时,Pt/RuO2/CNTs催化剂具有最佳的甲醇电催化氧化活性.RuO2负载在碳纳米管上比电容的变化,反映了水合RuO2结构中质子与电子传输平衡的能力,分析表明,催化剂中RuO2含量不同导致电容的变化是影响甲醇电催化氧化活性的主要原因.当催化剂结构中质子与电子传输达到平衡时,催化剂比电容最大,电催化氧化活性最高.这种基于电容关联电催化剂的观点对甲醇直接燃料电池阳极催化剂的设计非常有意义.     

以多聚甲醛为还原剂制备新型阳极Pt/CMK-3催化剂

 以多聚甲醛为还原剂,采用液相还原法制备了Pt/CMK-3直接甲醇燃料电池(DMFC)阳极催化剂,并采用透射电镜和X射线衍射技术对其进行了表征. 结果表明,有序介孔碳CMK-3具有规整的二维有序孔道结构,为DMFC中电子和燃料的传输提供了方便的路径,同时它较大的比表面积使得Pt纳米粒子很好地分散在其表面; Pt/CMK-3催化剂中Pt粒子的平均粒径为2.8 nm, 小于E-TEK公司的商品化Pt/XC-72和以甲醇为还原剂制备的Pt/C-M催化剂,并且粒径分布范围窄,结晶度低. 察了Pt/CMK-3催化剂对甲醇的电催化氧化性能,发现Pt/CMK-3催化剂对甲醇氧化的电催化性能优于Pt/XC-72和Pt/C-M催化剂.     

聚乙烯吡咯烷酮对Pt/Ru双金属纳米簇的结构和催化性能影响

以乙二醇为还原剂,通过微波热辐射制备得到稳定的Pt/Ru双金属胶体纳米簇,各颗粒粒径在1~2nm范围。考察了聚合物聚乙烯吡咯烷酮（PVP）对Pt/Ru双金属纳米簇表面原子组成及催化性能的影响。结果表明,PVP与金属前体之间的不同相互作用影响Pt/Ru双金属纳米簇的形成。在Pt/Ru双金属纳米簇形成之前加入PVP,Pt原子更容易富集在双金属表面,有利于增加Pt在催化反应中的作用。在PVP稳定的Pt/Ru双金属纳米簇中,除了零价态的Pt、Ru单质外,还存在氧化态的Pt化合物,归因于PVP与Pt前体的相互作用。在环己烯加氢反应中,PVP-Pt/Ru双金属纳米簇显示出比单金属纳米簇更优越的催化性能。     

聚乙烯吡咯烷酮对Pt/Ru双金属纳米簇的结构和催化性能影响

以乙二醇为还原剂,通过微波热辐射制备得到稳定的Pt/Ru双金属胶体纳米簇,各颗粒粒径在1~2 nm范围。考察了聚合物聚乙烯吡咯烷酮(PVP)对Pt/Ru双金属纳米簇表面原子组成及催化性能的影响。结果表明,PVP与金属前体之间的不同相互作用影响Pt/Ru双金属纳米簇的形成。在Pt/Ru双金属纳米簇形成之前加入PVP,Pt原子更容易富集在双金属表面,有利于增加Pt在催化反应中的作用。在PVP稳定的Pt/Ru双金属纳米簇中,除了零价态的Pt、Ru单质外,还存在氧化态的Pt化合物,归因于PVP与Pt前体的相互作用。在环己烯加氢反应中,PVP-Pt/Ru双金属纳米簇显示出比单金属纳米簇更优越的催化性能。     

cotpp-pt/c作直接甲醇燃料电池阴极催化剂

四苯基钴卟啉;pt催化剂;直接甲醇燃料电池;氧还原     

Spherical carbon capsules with hollow macroporous core and mesoporous shell structures as a highly efficient catalyst support in the direct methanol fuel cell

Carbon capsules with hollow core and mesoporous shell (HCMS) structures were used as a support material for Pt(50)-Ru(50) catalyst, and the catalytic performance of the HCMS supported catalyst in the direct methanol fuel cell was described; the HCMS carbon supported catalysts exhibited much higher specific activity for methanol oxidation than the commonly used E-TEK catalyst by about 80%, proving that the HCMS carbon capsules are an excellent support for electrode catalysts in DMFC.     

高活性甲醇氧化电催化剂Pt-Pd纳米合金的组分可控合成

Pt纳米粒子由于其本身独特的物理、化学性质以及能够同时促进氧化和还原反应,在工业生产和商业设备中(尤其在直接甲醇燃料电池中)广泛用作重要的电催化剂.然而,Pt作为贵金属在自然界中的含量极其稀少,价格昂贵;另外,甲醇氧化反应中产生的中间产物CO很容易市Pt纳米粒子中毒而失活.因此,迫切需要一种Pt用量少,催化性能高的材料.一制备高活性比表面积的Pt纳米颗粒,可以有效提高Pt利用率.另外,调控纳米粒子使其裸露特定的晶面、边、角以及缺陷也能有效提升催化性能.还可以采用Pt纳米粒子结合其它金属元素形成双金属合金,如,Pt-M (M = Pd,Au,Ag,Ru,Fe,Co,Ni,等)催化剂,可以在减少Pt元素用量的同时有效提升催化活性.在众多可供选择的元素中,Pd相对于Pt价格低廉,但两者具有相近的物理、化学性质以及较高的电催化性能,使Pt-Pd纳米合金呈现十分优异的电催化性能.研究表明,Pt-Pd纳米合金在酸性和CO环境中能有效催化有机小分子电氧化过程.另外,在酸性环境中,用Pd替代Cu,Ag,Co或Ni,可以有效减少催化剂的腐蚀.本文在乙二醇溶液中同时还原K2PtCl4和Na2PdCl4,在110 ℃C反应5 h制备出超细的Pt-Pd纳米合金.通过X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)以及能谱仪(EDS)对合金进行表征,从而确定产物为尺寸4 nm左右的Pt-Pd纳米合金,且通过改变金属前驱体的投料比可以有效调控Pt-Pd合金组分(按元素比例分别表示为Pt1Pd3,Pt1Pd1,Pt3Pd1).采用循环伏安法、线性扫描伏安法以及计时安培法等多种手段测试样品在0.5 mol/L H2SO4和0.5 mol/L CH3OH的酸性环境中(50 mV/s)电化学性能,并与商业Pt/C进行比较.结果表明,合金的催化性能和组分密切相关,当Pt元素的含量为75%左右时,Pt-Pd纳米合金表现出最佳的催化活性和稳定性,其中Pt3Pd1的电催化质量活性可达商业Pt/C的7倍之多.我们把Pt-Pd纳米合金的催化性能对其组分的依赖性归结为甲醇氧化反应中的双官能团机制,反应中,Pt可有效催化甲醇脱氢产生Pt-CO,Pd则催化水脱氢形成Pd-OH.当Pd含量减少时,Pt表面的水脱氢反应只有在高电位才能发生,从而降低催化效率;而Pd含量过多,则会抑制Pt催化甲醇的脱氢反应,使催化效率大大降低.因此,只有适宜Pt/Pd比例,才能有效提升催化效率.     

Mn3O4 catalyzed growth of polycrystalline Pt nanoparticles and single crystalline Pt nanorods with high index facets

Rarely-observed polycrystalline twinned Pt nanoparticles (NPs) and length-controlled Pt nanorods (NRs) with exposed high index facets were prepared through an unexpectedly catalytic growth approach from low-cost Mn(3)O(4) NPs. The as-prepared Pt NRs exhibit higher catalytic activity and better stability for the oxidization of methanol than commercial Pt/C catalysts, indicating the promise of this catalyst in direct methanol fuel cells.     

嵌段共聚物模板法一步制备WC/C基底电极材料

以酚醛树脂作为碳源,采用嵌段共聚物模板法一步制备新型有序介孔碳化钨/碳（WC/C）纳米颗粒. WC/C颗粒的比表面积为414 m²·g^-1,表面的平均孔径约为38 nm,处于介孔范围内（2 ~ 50 nm）. 通过调节树脂预聚时间以及碳化温度等条件制备出结构形貌较优的WC/C复合材料,并探讨了材料形成机理. 使用X射线衍射、扫描电镜、透射电镜及氮气吸脱附等方法表征了复合材料的结构. 将贵金属铂负载于WC/C表面制备得新电催化材料Pt-WC/C,使用循环伏安法和计时电流法对Pt-WC/C复合材料的电化学性能进行检测,并与商用碳载铂（Pt/C）材料进行对比. 测试结果发现,Pt-WC/C对甲醇的电催化活性以及稳定性等方面都表现出优于商用Pt/C材料的活性,这主要归功于碳化钨高度分散于碳表面.     

Pt?M (M=Cu,Co, Ni,Fe) Nanocrystals: From Small Nanoparticles to Wormlike Nanowires by Oriented Attachment

Pt? M (M=Cu, Co, Ni, Fe) wormlike nanowires with excellent catalytic activities were produced by a hydrothermal method. Based on the experiment results, Pt? M nanoparticles grew into nanowires through oriented attachment. The electrocatalytic activities of these nanowires toward methanol oxidation were also studied by cyclic voltammetry and chronoamperometry measurements. The synthesized Pt? M nanowires showed higher catalytic activity and stability for methanol oxidation than Pt nanowires and commercial Pt black.     

Technical electrodes catalyzed with PtRu on mesoporous ordered carbons for liquid direct methanol fuel cells

This paper presents the behavior of ordered mesoporous carbon (OMC)-supported catalysts as anodes for direct methanol fuel cells (DMFC), fed with an aqueous methanol solution. OMC samples were prepared by the nanocasting method from a polymerized furan resin using mesoporous silica as a template. Pt and PtRu nanoparticles were supported on OMC with high dispersion, the particle size being 2.4 nm at PtRu loading of 15 wt.%. The resulting catalysts were analyzed using carbon monoxide stripping voltammetry, cyclic voltammetry, and chronoamperometry in three-electrode experiments and recording cell voltage vs. current density curves in practical DMFC. It was found that PtRu-catalyzed technical electrodes exhibited good activity towards methanol electrooxidation in half-cell experiments under fuel-cell-relevant conditions. Specifically, Pt₈₅Ru₁₅/OMC catalyst showed the highest catalytic enhancement compared to Pt/OMC for the steady-state electrooxidation of methanol at 60 °C and 0.5 V, by a factor of 22 in 2-M MeOH solution. DMFC single cells yielded an open-circuit voltage of 0.625 V at 60 °C. Polarization curves indicate that DMFC with OMC-supported Pt₈₅Ru₁₅ catalyst at the anode exhibited the best performance.     

Nanoscale Perovskites as Catalysts and Supports for Direct Methanol Fuel Cells

With the ultimate goal of simultaneously finding cost-effective, more earth-abundant, and high-performance alternatives to commercial Pt/Pd-based catalysts for electrocatalysis, this review article highlights advances in the use of perovskite metal oxides as both catalysts and catalyst supports towards the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) within a direct methanol fuel cell (DMFC) configuration. Specifically, perovskite metal oxides are promising as versatile functional replacements for conventional platinum-group metals, in part because of their excellent ionic conductivity, overall resistance to corrosion, good proton-transport properties, and potential for interesting acidic surface chemistry, all of which contribute to their high activity and reasonable stability, especially within an alkaline electrolytic environment.     

高耐甲醇性和稳定性的纳米复合阴极催化剂

报导了一种由酞菁氧钛、铂金属纳米簇和氮杂化碳纳米角结构基元组装而成的新型纳米复合电化学催化剂(TiOPc-Pt/NSWCNH)的制备、表征及电催化性能. 在TiOPc-Pt/NSWCNH催化剂中, 氮杂化碳纳米角堆积形成多孔导电网络, 铂纳粒子均匀地分散于上述多孔导电网络中, 部分铂纳粒子与TiOPc微晶直接接触. 在甲醇存在的条件下, TiOPc-Pt/NSWCNH对氧还原反应表现出高催化活性和优良的选择性与稳定性. 在甲醇浓度为0.5 mol·L^-1的高氯酸水溶液中, TiOPc-Pt/NSWCNH催化氧还原反应的起始电位比商购Pt/C-JM催化剂提高了260 mV, 其质量活性和比活性(0.85 V (参比电极为可逆氢电极(RHE)))分别为83.5 A·g^-1和0.294 mA·cm^-2, 远高于Pt/C-JM催化剂. 在含氧气氛下, 于甲醇高氯酸水溶液中, 对TiOPc-Pt/NSWCNH和TiOPc-Pt/C催化剂进行了循环伏安法加速老化实验研究(0.6-1.0 V, 15000个循环), 结果表明TiOPc-Pt/NSWCNH具有更高的稳定性. TiOPc-Pt/NCNH催化剂的高耐醇性可能得益于由TiOPc微晶向Pt纳米粒子的电子转移, 其高稳定性主要得益于氮杂化碳纳米角的高石墨化程度及纳米角堆积而成网络结构.     

High performance electrocatalyst: Pt-Cu hollow nanocrystals

Pt-Cu hollow nanocrystals with excellent electrocatalytic activities were produced by a one-pot synthesis method. The catalytic activities of these nanocrystals toward methanol electro-oxidation were studied by cyclic voltammetry (CV). The Pt-Cu hollow nanocrystals exhibited higher catalytic activity for methanol oxidation than commercial Pt black and Pt/C.     

A catalytic gas diffusion layer for improving the efficiency of a direct methanol fuel cell

The efficiency of a single direct methanol fuel cell (DMFC) with Pt–Ru decorated carbon nanotubes directly grown on carbon cloth (Pt–Ru/CNTs/CC) as a catalytic gas diffusion layer (GDL) at the anode was evaluated by polarization analysis. Pt–Ru nanoparticles were electrodeposited on dense carbon nanotubes directly grown on carbon cloth in ethylene glycol containing sulfuric acid solutions. The presence of relatively well dispersed Pt–Ru nanoparticles (4–6 nm) on the surfaces of CNTs was confirmed by transmission electron microscopy. Two more GDLs, one with dense CNTs but without the presence of Pt–Ru nanoparticles and the other with neither CNTs nor catalysts, were also prepared for comparison purpose. For quantitatively evaluating the performance of the catalytic GDL, three identical membrane–electrode-assemblies were prepared and laminated with different GDLs before they were used to construct DMFCs for performance test. It was found via polarization analyses the catalytic GDL was able to promote the peak specific power density of the DMFC by 27% at ambient temperature.     

New route to synthesis of PVP‐stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross‐coupling reactions

Herein we report a new method for the synthesis and characterization of PVP‐stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP‐stabilized palladium(0) nanoclusters with a particle size of 4.5 ± 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 °C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV–vis, and XRD techniques. The PVP‐stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP‐stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd.     

Pt(Cu)/C Electrocatalysts with Low Platinum Content

The structure characteristics and the electrochemical behavior of Pt(Cu)/C electrocatalysts synthesized by consecutive deposition of copper and platinum on carbon-support microparticles is studied. The stability and catalytic activity of Pt(Cu)/C materials in reactions of oxygen electroreduction and methanol electrooxidation are assessed and compared with analogous characteristics of a commercial Pt/C material. It is shown that combining the method of galvanic displacement of Cu by Pt with the additional chemical deposition of Pt favors optimization of the structure and functional characteristics of Pt(Cu)/C electrocatalysts. The effect of thermal treatment on the characteristics and properties of electrocatalysts is studied and the optimal conditions of such pretreatment are revealed.