Microwave radiation-assisted synthesis of Pt-CNTs

Carbon nanotube-supported platinum nanoparticles (Pt-CNTs) were synthesized using glycol as a reducer and H2PtCl6 as an oxidant under microwave radiation. The CNTs was first hydroxylated in refluxing concentrated HNO3. Transmission electron microscopy was used to investigate the influence of the hydroxylation time on the amount of supported platinum on the carbon nanotubes and the effect of the amount of platinum on the morphology of Pt-CNTs. Selected area electron diffraction, X-ray diffraction, and UV-visible spectroscopy were employed to characterize the structure of the Pt-CNTs and the results showed that Pt was of polycrystal nanoparticles. Cyclic voltarnmetric study indicated that the CNTs surface was covered by a compact layer of Pt when the loadings of platinum to CNTs was as high as 0.1875 mmol . g(-1). The result, on one hand, showed that cyclic voltammetry could be used to study the surface structure and properties of CNTs supported platinum nanoparticles, and on the other hand, indicated that it was possible to obtain novel electrode materials with good catalytic activity and stability by optimizing the synthesizing method for CNTs supported platinum nanoparticles

甲酸在Pt-Ru/GC电极上氧化的SERS研究

采用循环伏安(CV)法、计时电流法和电化学原位表面增强拉曼散射光谱(SERS)技术研究了甲酸在Pt-Ru/GC电极上的氧化行为,发现甲酸在Pt-Ru/GC电极上与在粗糙Pt电极上一样,也能自发解离出强吸附中间体CO和活性中间体—COO-.从分子水平证实钌的加入有利于提高电极对甲酸的电催化氧化活性,当镀液中Pt:Ru的摩尔比从10∶1变化到1∶1,CO的氧化峰电位从0.41V负移至0.35V,约负移了60mV.Pt-Ru/GC(1∶1)电极与粗糙Pt电极相比,CO在电极表面氧化完毕的电位亦负移了约200mV.该研究结果表明,电化学原位表面增强拉曼散射光谱技术可望成为研究电催化反应机理的普适谱学工具

甲酸在铂钌电极上电催化氧化的原位SERS研究

采用循环伏安法和电化学原位表面增强拉曼光谱(in-situ SERS)技术研究了甲酸在铂钌电极上解离吸附与氧化行为。发现甲酸在铂钌电极上也能自发解离吸附。铂钌电极上CO的氧化峰电位与粗糙铂电极相比负移了180mV,把CO氧化完毕的电极电位亦负移了300 mV,从分子水平证实铂钌电极对甲酸电催化氧化的活性比纯铂电极更高。该研究结果表明,SERS技术可望拓展为研究电催化体系的有效工具

Pt-CNTs修饰玻碳电极(Pt-CNTs/GC)电氧化活性的研究

采用透射电镜(TEM)和选区电子衍射(SAED)技术,分别表征了Pt-CNTs/GC电极的表面形貌和所负载铂纳米原子簇的结构.以CO和CH3OH为探针分子,用循环伏安和计时电流等常规电化学方法检测了CO和CH3OH在Pt-CNTs/GC电极上的氧化行为.研究结果表明,CO在Pt-CNTs/GC电极上有3个氧化电流峰(Ⅰ,Ⅱ,Ⅲ),其中峰Ⅰ为CO桥式吸附的氧化峰,而峰Ⅱ和Ⅲ则分别为CO线形吸附在碳纳米管负载的不同粒径的Pt纳米原子簇以及Pt原子薄膜上所分裂的氧化峰;CH3OH在Pt-CNTs/GC电极上也能自发解离吸附强吸附中间体CO;Pt-CNTs/GC电极对CH3OH的氧化峰电流不总是随CNTs上载铂量的增加而增大,表明在制备直接甲醇燃料电池阳极时,应选择合适的载铂量

微波法在碳纳米管上负载铂纳米粒子

以乙二醇作氯铂酸的还原剂,采用微波法在浓硝酸回流纯化和羟基化的碳纳米管(CNTs)上负载铂纳米粒子,并通过控制载铂量制备出以CNTs为衬底的铂纳米管(Pt-CNTs);用透射电镜比较了纯化和羟基化时间对CNTs载铂性能以及不同载铂量对Pt-CNTs表面形貌的影响;用选区电子衍射﹑X射线衍射和紫外-可见吸收光谱检测了Pt-CNTs的结构特征,表明CNTs表面所负载的是多晶铂;用电化学循环伏安技术表征碳纳米管负载铂纳米粒子,发现当Pt-CNTs的载铂量为0.1875mmol·g-1时,CNTs表面负载了一层致密的铂纳米粒子

乙醇在不同介质中电氧化的原位表面增强拉曼光谱研究

采用常规电化学伏安技术和电化学原位表面增强拉曼光谱(in-situ SERS)技术研究了不同介质中乙醇在粗糙铂电极上的电催化氧化行为.发现不论在酸性、中性还是碱性介质中,乙醇均能在粗糙铂电极上自发氧化解离生成强吸附中间体CO;碱性介质中,CO在粗糙铂电极上基本氧化完全的电位(0.20 V)比中性和酸性介质中(0.50 V)负移了约0.30 V.而乙醇在粗糙铂电极上CV正向扫描的氧化峰电位(-0.20 V)比酸性介质中(0.65 V)负移了约0.85 V.比较不同介质中乙醇和CO在粗糙铂电极上的氧化峰电流和峰电位可以发现,粗糙铂电极在碱性介质中对乙醇和CO的电催化氧化活性比中性和酸性介质中更强;可以推测,不论在酸性、中性还是碱性介质中,乙醇在粗糙铂电极上的氧化过程均按双途径机理进行

Pt-Sn/Pt电极对乙二醇的电催化氧化

采用常规电化学方法研究了Pt/Pt与Pt和Sn配比不同的Pt-Sn/Pt电极对乙二醇(EG)的电催化氧化行为。结果表明,EG在Pt/Pt和Pt-Sn/Pt电极上均能自发氧化解离,产生强吸附中间体COad。而Sn的加入,可抑制EG的自发氧化解离,且在一定范围内随着Sn含量的逐渐增加(Sn/Pt从0.25增加至0.67),EG在Pt-Sn/Pt电极上自发氧化解离所产生的CO吸附量逐渐减少,Pt-Sn/Pt电极对EG电催化氧化的活化能逐渐降低(从44.21降至32.11kJ/mol)。与Pt/Pt电极相比,Pt-Sn/Pt(Sn/Pt=0.67)电极对EG电催化氧化的活性得到明显提高

Investigation of Electro-oxidation activity of Pt-CNTs/GC electrodes

The morphology and the structure character of the Pt-CNTs/GC electrode were characterized via Transmission Electron Microscopy ( TEM) and the selected area electron diffraction. The electro-oxidation behavior of CO and methanol on Pt-CNTs/GC electrode were studied with cyclic voltammograms or Chronoamperometry. Three oxidation peaks were observed for CO observed on Pt-CNTs/GC electrode. Methanol were found to be dissociated spontaneously on the electrode to produce a strong adsorbed intermediate CO. Among the three oxidation peaks, peak I is due to the briged CO adsorbing. But peaks II and III were assigned to split of the linear CO which is adsorbed on the Pt-CNTs nanocluster with different particle sizes and Pt film. The oxidation current of methanol on Pt-CNTs/GC electrode was- always not increasing with the increasing of the amount of Pt loading. The result indicates that there is an optimal Pt loading for methanol oxidation. It is necessary to select the catalyst with proper pt loading when the anode of direct-methanol fuel cell was prepared

In-situ surface-enhanced Raman spectroscopic investigation on ethanol electrooxidation in different media

Electrochemical voltametric methods and in-situ electrochemical surface-enhanced Raman spectroscopy (SERS) were used to investigate the electrooxidation behavior of ethanol in different media on a roughened platinum electrode. It was found that ethanol could dissociate spontaneously to produce strongly adsorbed intermediate, CO, in acidic, neutral, and alkaline media on the roughened platinum electrode. The complete oxidation potential of COad on the roughened platinum electrode was negatively shifted about 0.300 V in the alkaline medium (0.20 V) compared with that in the acidic and neutral media (0.50 V). The positive oxidation peak potential of ethanol was negatively shifted about 0.85 V in the alkaline medium (-0.20 V) than that in the acidic medium (0.65 V). By comparing the oxidation current and the peak potential, it was found that the electrocatalytic activity of roughened platinum electrode for ethanol and CO oxidation in the alkaline medium was higher than in acidic and neutral media. The results suggested that ethanol was oxidized to CO2 on the roughened platinum electrode via parallel reaction mechanism in acidic, neutral or alkaline media