碳载铂电极在甲酸氧化中的电催化特性

本文通过对碳载铂电极在甲酸氧化中电催化特性的研究,提出了一种制备高活性、低成本新型实用型电催化剂的方法,在理论上为甲酸氧化的双途径机理提供了实验依据

Abnormal Infrared Effects (AIREs) of nm-Ru/GC Electrode Towards CO Adsorption in Alkaline Solutions

研制纳米级厚度的Ru薄膜电极 ,并运用电化学原位FTIR反射光谱研究碱性介质中CO的吸附。检测到CO以线型吸附态为主 ,但也存在少量桥式吸附态 ,分别在 196 0和 1780cm-1附近给出红外吸收谱峰。发现纳米Ru膜电极具有异常红外效应 ,即CO谱峰方向倒反 ,强度增强和半峰宽增加。测得在碱性溶液中吸附态CO的红外吸收被增强了 33倍 ,其增强因子是酸性溶液中的两倍左右。The adsorption of CO on electrode of nanometer thin film of Ru in 0 1 mol·L -1 NaOH solution was studied by using in situ FTIR spectroscopy.The results revealed that the adsorbed CO in alkaline solutions is mainly in linear bonded form that yields IR absorption at around 1 960 cm -1 ,and a small portion of bridge bonded CO was also determined near 1 780 cm -1 .The band centers of CO L and CO B have been red shifted respectively about 50 and 60 cm -1 in comparision with the values measured in acid medium.The enhancement factor of IR absorption of CO on nm Ru/GC electrode has been measured at 33 in 0 1 mol·L -1 NaOH solution,which is more than 2 times larger than the value determined in a 0 1 MH 2SO 4 solution.国家自然科学基金!(2 98330 60 );; 教育部科学技术重点研究项目!(991 77)资

玻碳表面铂黑电极的结构与电催化活性

在电化学催化的应用研究中,至关重要的课题之一,莫过于寻找和制备高性能电催化剂.以碳或氧化物为载体,在其表面上沉积催化物质,可显著提高催化剂的利用率,降低成本.铂的催化活性较高,因此,对载体上沉积铂制备实用型电催化剂的研究一直受到重视.近十多年来,以原子排列结构明确的铂单晶面作为模型催化剂的研究取得了极大的进展,发现铂电极表面结构对其活性具有决定性的影响.从而可能通过获得的知识在原子和分子层次上对电催化剂表面进行设计和筛选.由于金属在一定条件下存在单晶多定向,以及多晶单定向的趋势,上述可能性就更接近实际.本文通过对玻碳表面沉积的高分散铂黑电催化剂的结构和对甲醇氧化的催化活性的研究,试图在微观层次上对实用型电催化剂表面结构及性能进行探讨

Electrochemical and In situ FTIR Studies of Maleic Acid Reduction in BF_4

作者自行合成了离子液体[BMIM]BF4,用循环伏安法(CV)、计时电量法(CA)和电化学原位红外反射光谱(in situFTIR),从分子水平考察了离子液体中马来酸在玻碳(GC)电极上的电化学还原过程。结果表明,[BMIM]BF4中马来酸在GC电极上的还原为不可逆过程,测得扩散系数D=9.62×10-8cm2/s;in situFTIRS研究发现,马来酸在离子液体[BMIM]BF4和水溶液中的电还原生成丁二酸的机理不同。在[BMIM]BF4中马来酸还原发生在其中的一个羧基上,即马来酸首先获得一个电子生成阴离子自由基,随后可能获得一个电子生成二价阴离子,或者获得一个电子并在2个H+的作用下生成醛类物质和水。The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborates(BF4) was synthesized and used as both solvent and electrolyte.Electrochemical reduction of maleic acid in the ionic liquid was studied by cyclic voltammetry(CV),chronoamperometry(CA) and in situ FTIR spectroscopy.The results demonstrated that the reduction of maleic acid on GC electrode is an irreversible process controlled by diffusion.The diffusion coefficient D of maleic acid is determined to be 9.62×10-8 cm2/s.in situ FTIR results illustrated that the reduction of maleic acid in ionic liquids occurs on the carboxyl.The first step is to geaerte radical anions,which are reduced then to aldehyde species and water with two hydrogen ions.国家自然科学基金(批准号:20673091,20833005)~

In Situ FTIRS Studies of CO_2 Reduction on Thin Film Alloy El ectrodes

运用电化学循环伏安和原位FTIR反射光谱 ,研究CO2 的电催化还原过程。结果表明 ,纳米薄膜合金材料Sb Pb Pt/GC对CO2 还原具有较高的活性。还原产物以小分子羧酸和伯醇为主。The nanometer thin film alloy electrode (Sb-P b -Pt/GC)was prepared by electrochemical methods.Excellent catalytic effect was o bserved on these film alloy material in the electro-reduction of carbon dioxide (CO 2).The reduction can take place at potentials as high as -0 4 V.The oxid ation of reduced products of CO 2 on Sb-Pb-Pt/GC yielded current peaks at arr owd -0 08,0 2 and 0 3 V,while the oxidation of reduction products on a nm-P t/GC electrode gave rise a current peak near 0 4 V.The in situ FTIR spectroscop ic studies confirmed at a molecule level that the products of CO 2 reduction on Sb-Pb-Pt/GC are mainly organic acid and alcoholic compounds,while on a nm-Pt /GC electrode the production of CO 2 is mainly CO species.国家自然科学基金!(2 99730 35);; 福建省基金!(E991 0 0 0 3)资

Preparation and Characterization of Electro-catalyst of Surface Alloy Supported on Glassy Carbon

以玻碳为载体 ,通过电化学方法在其表面沉积催化物质研制表面合金纳米电催化剂 (Surfacealloy/GC)。运用电化学循环伏安 (CV)和扫描电镜 (SEM)等技术进行结构和性能表征。结果表明 ,在Surfacealloy/GC上氢的析出电位负移至 - 0 40V(SCE) ,与Pt电极相比负移约 15 0mV ,具有较高的电还原应用价值。另外 ,Surfacealloy/GC的氧化电位正移至 0 64V ,其稳定性明显高于电有机合成中常用的Pb、Sb、Cu等金属电极。SEM研究结果表明 ,所研制的Surfacealloy/GC电催化剂是一种由粒度约为 70nm的纳米颗粒合金组成的薄膜Electro-catalysts of surface alloy supported on glassy carbon (GC) were prepared by electrochemical codeposition method. Structures and properties of these electro-catalysts were studied through techniques of cyclic voltammetry (CV) and scanning electron microscope (SEM). The results demonstrated that the onset potential of hydrogen evolution on the surface alloy/GC was postponed to -0.40V,i.e.,negatively shifted by 150 mV in comparison with that of hydrogen evolution on a platinum electrode. In addition, the oxidization potential of the surface alloy/GC was positively shifted to above 0.64V, which is much higher than the oxidization potential of Pb and Sb metal electrodes. This indicates that the stability of the surface alloy/GC electrode is higher than that of Pb, Sb and Cu metal electrodes usually employed in organic electrosynthesis.The results of characterization by SEM have converged to illustrate that the surface alloy film is composed of nano-particles of about 70 nanometers in regular distribution.厦门市科技攻关项目基金资助 (35 0 2Z2 0 0 1);; 福建省自然科学基金资助 (E9910 0 0 3);; 国家自然科学基金 (2 98330 60 ,2 0 0 2 10 0 2 )资

Study on Electrocatalytic Oxidation of sec-Butyl Alcohol on Pt Electrode Modified with Adatoms

运用电化学循环伏安和石英晶体微天平研究了HClO4溶液中仲丁醇在Pt电极及以Sb和S吸附原子修饰的Pt(Pt/Sbad和Pt/Sad)电极上的电催化氧化过程 .从电极表面质量变化可以看出 ,仲丁醇的氧化与电极表面的氧物种有着极其密切的关系 .Pt电极表面Sb吸附原子可在较低的电位下吸附氧 ,明显提高仲丁醇的氧化活性 .与Pt电极相比 ,Sb吸附原子修饰的Pt电极使仲丁醇氧化的峰电位负移约 10 0mV .相反 ,Pt电极表面S吸附原子的氧化会消耗表面氧物种 ,抑制仲丁醇的氧化 .从电极表面质量变化提供了吸附原子电催化作用的数据The processes of adsorption and oxidation of sec butyl alcohol on Pt electrode and Pt electrodes modified with Sb and S (Pt/Sb ad and Pt/S ad ) were studied by using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The results demonstrated that the oxidation of sec butyl alcohol depends strongly on oxidation states of electrode surface. Sb adatoms on Pt surface can adsorb oxygen at relatively low potentials, and exhibit catalytic effects for sec butyl alcohol oxidation. In comparison with the case of Pt electrode, the oxidation peak potential of sec butyl alcohol on Pt surface modified with Sb was negatively shifted about 100 mV. On the contrary, the oxidation of S adatoms consumes oxygen species on Pt electrode surface. As a consequence, the oxidation of sec butyl alcohol was inhibited by the presence of S ad . The EQCM studies provided quantitative results of surface mass changes during sec butyl alcohol oxidation, and have thrown new light on elucidating different effects of adatoms Sb ad and S ad on Pt electrode towards sec butyl alcohol oxidation.国家自然科学基金 (2 983 3 0 60 );; 教育部博士点专项科研基金 (19990 3 840 3 );; 福建省教委科研基金资助项目 (K2 0 0 110 1

Effect of Specific Adsorption of Anions and Surface Structure of Pt(111) Electrode on Kinetics of Dissociative Adsorption of Ethylene Glycol

运用电化学循环伏安和程序电位阶跃方法研究了阴离子特性吸附和PT(111)电极表面结构对乙二醇解离吸附反应动力学的影响.结果表明,阴离子特性吸附显著影响乙二醇的解离吸附,在高氯酸介质中(无特性吸附)测得乙二醇解离吸附反应的初始速率VI以及解离吸附物种(dA)的饱和覆盖度均明显大于硫酸溶液(发生SO24-/HSO4-特性吸附)中的相应值;其平均速率V随电极电位的变化呈类似火山型分布,最大值位于0.22V(VSSCE)附近.还发现通过不同处理获得的PT(111)电极的不同表面结构对这一表面过程也具有显著的影响.The effect of specific adsorption of anions and the surface structure of a Pt(111) electrode on the kinetics of dissociative adsorption of ethylene glycol (EG) was studied using cyclic voltammetry and a programmed potential step technique.Quantitative results demonstrated that the specific adsorption of anions remarkably influenced the dissociative adsorption of EG.Both the initial reaction rate (vi) of the EG dissociative adsorption and the saturated coverage of dissociative adsorbates, measured in perchloric acid media (without specific adsorption), are significantly larger than the corresponding values acquired in sulfuric acid media (with specific adsorption of SO420-/HSO4-).We illustrate that the variation of the average reaction rate v of EG dissociative adsorption on Pt(111) in perchloric acid media with an electrode potential yields a volcano-like distribution with a maximum value near 0.22 V (vs SCE).Furthermore, different surface structures of the Pt(111) electrode that were obtained by different treatments also significantly affect this surface process.国家自然科学基金(20673091;20833005);广西师范大学博士科研启动基金资

In Situ FTIR Spectrocopic Studies of CO and CN~- Adsorbed on Electrode of Nanometer Thin Film of Palladium in Alkaline Solutions

以原位FTIR反射光谱研究碱性介质中CO和CN-在纳米Pd膜电极上的吸附和共吸附 ,进一步揭示了纳米薄膜材料的异常红外效应和CO与CN-共吸附时的相互作用规律。The adsorption and coadsorption of CO and CN- - on electrode of nanometer thin film of palladium (nm-Pd/GC)was studied by usin g in situ FTIR spectroscopy.The results demonstrated that the nm-Pd/GC electrod e exhibited abnormal infrared effects (AIREs) in alkaline solutions as in acid s olutions.The characters of AIREs,i.e.,the inversion of the direc tion of IR band,the augmentation of FWHM and the significant enhancement of IR a bsorption by adsorbed species were observed in all cases of adsorption and coads orption of CO and CN--.It has been illustrated that strong interaction is exis ted between adsorbed CO and CN-- on nm-Pd/GC surface.The study has contribute d towards understanding the surface processes of chemisorption as well as to rev eal the origin of nanometer size-effects of thin film materials.国家自然基金!(2 98330 60 );; 教育部博士点基金!(1 9990 3840 3)资

Reduction of Oxalic Acid on Surface Alloy/GC Electrode Studied by Using CV and in situ FTIR Spectroscopy

采用自行研制的碳载表面合金电催化材料 (Surfacealloy/GC)作为研究电极 ,通过电化学方法和电化学原位FTIR反射光谱等技术 ,对该催化剂在电有机合成中的性能进行研究。结果表明 :所研制的Surfacealloy/GC对草酸的加氢还原表现出很高的电催化活性 ,草酸的还原电位为 - 0 .40V ,与通常用的阴极铅材料相比 ,正移约6 0 0mV ;电化学原位FTIR反射光谱研究结果指出 ,草酸的还原产物主要为乙醛酸 ,表明该电极在较低的过电位下就能还原草酸生成乙醛酸。Reduction of oxalic acid on electrode of surface alloy supported on glassy carbon was studied by using cyclic voltammetry and in situ FTIR spectroscopy.The results demonstrated that the surface alloy exhibited a high electrocatalytic activity towards oxalic acid reduction.The over potential of oxalic acid reduction was significantly reduced by about 600 mV in comparison with that measured on a Pb cathode that was used industrially for the reduction. The main reduction product identified by using in situ FTIR spectroscopy was glyoxylic acid,indicating that the surface alloy/GC electrode exhibited an excellent selectivity for glyoxylic acid in oxalic acid reduction.厦门市科技攻关项目基金资助 ( 35 0 2Z2 0 0 1) ;; 福建省自然科学基金资助 (E9910 0 0 3) ;; 国家自然科学基金资助 ( 90 2 0 6 0 39,2 0 0 2 10 0 2 )~