电化学原位扫描显微红外反射光谱及其对铂表面CO吸附的红外成象

利用Fourier变换红外光谱仪 ,红外显微镜和X Y扫描平台 ,通过设计和研制原位红外显微池和计算机接口及控制软件 ,建立了电化学原位扫描显微红外反射光谱 .研究工作显示 ,这一新的空间分辨原位红外反射光谱技术不仅可以获得固 /液界面环境中表面微区振动光谱的信息 ,还可以用于电极表面红外成象 .获得的CO在Pt多晶电极表面吸附性能的化学图象在 10 -2 cm尺度上给出电极表面微区反应性能的不均一性及其分布 .     

碱性介质中甘氨酸在Pt电极上解离吸附和氧化反应的原位红外反射光谱研究

运用原位红外反射光谱研究了碱性介质中甘氨酸在Pt电极上的解离吸附和氧化反应行为,并利用纳米Pt膜电极的异常红外效应鉴定反应过程中生成的表面吸附物种.结果表明:甘氨酸在Pt电极上极易发生解离,生成强吸附于电极表面上的氰基负离子,该吸附物种在低于0V电位下能稳定存在,并抑制甘氨酸的进一步反应.当电位高于0.2V时,氰基负离子被氧化为氰酸根离子进入溶液,使甘氨酸发生氧化反应,生成氰酸盐和碳酸盐等产物.     

纳米金膜电极上CN~-吸附的电化学和原位红外反射光谱研究

应用循环伏安(CV)和原位红外反射光谱(in situFTIRS)研究碱性介质中氰(CN-)在纳米金膜电极(nm-Au/GC)上的吸附行为.结果显示,当研究电极电位低于0.0 V时,CN-可稳定吸附在nm-Au/GC电极表面,高于0.0 V,则发生氧化脱附.发现nm-Au/GC表面具有异常红外效应(AIREs),即吸附态CN-谱峰呈现出与本体Au电极不同的方向倒反、红外吸收增强(39.2倍)以及半峰宽增加的异常光谱特征.本研究将纳米薄膜材料的这一AIREs从过渡金属拓展到币族金属,进一步证明AIREs是迄今研究的金属及合金纳米材料的普遍特性.     

碱性介质中甘氨酸在Pt电极上解离吸附和氧化反应的原 …

运用原位红外反射光谱研究了碱性介质中甘氨酸在Ｐｔ电极上的解离吸附和氧化反应行为,并利用纳米Ｐｔ膜极的异常红外效应鉴定反应过程中生成的表现吸附物种。结果表明,甘氨酸在Ｐｔ电极上极易发生解离,生成强吸附于电极表面上的氰基负离子。     

表面增强拉曼光谱和红外光谱电化学实验

本文通过硫脲在银电极上吸附和正丙醇在铂电极上氧化的两个具体实例，简要介绍表面增强拉曼散射和红外反射光谱的教学实验内容。     

酸性溶液中过渡金属及合金纳米薄膜电极的异常红外效应研究

以循环伏安方法在玻碳载体上制备纳米级厚度的过渡金属 (Pt,Pd ,Rh ,Ru)和合金 (PtPd ,PtRu)薄膜电极 ,并运用原位FTIR反射光谱研究了CO的吸附过程 .发现所制备的纳米薄膜电极均具有异常红外效应 ,即与本体金属电极相比较 ,吸附在纳米薄膜电极上的CO分子的红外吸收被显著增强 ,并且红外谱峰方向倒反 .本文的结果进一步证明异常红外效应是一种新的、普遍的现象 ,主要取决于过渡金属或合金膜的结构和厚度 .对异常红外效应的深入认识 ,不仅将推动红外反射光谱及界面电化学理论的发展 ,而且将在表面和界面分析中得到广泛应用 .     

利用原位红外光谱与微分电化学质谱联用技术研究在Pt以及PtRu电极上发生的甲醇氧化反应

利用电化学衰减全反射原位傅里叶变换红外光谱与微分电化学质谱联用技术,在流动电解池环境以及恒电位条件下研究了Pt电极和Pt电极通过表面电沉积Ru形成的PtRu电极（PtxRuy）上发生的甲醇氧化反应（反应电解质溶液为0.1 mol/L HClO4＋0.5 mol/L MeOH）. 在0.3-0.6 V（参比电极为可逆氢参比）实验用到的所有电极上,CO是唯一能从红外光谱观察到的与甲醇相关的表面吸附物;在Pt0.56Ru0.44电极上可以观察到CO吸附在Ru原子形成的岛上和CO线式吸附在Pt电极表面红外波段,而其他电极上只能观察到Pt表面上线式吸附的CO;甲醇氧化活性按Pt0.73Ru0.27〉Pt0.56Ru0.44〉Pt0.83Ru0.17〉Pt的顺序递减;在0.5V时,甲醇在Pt0.73Ru0.27电极上的氧化反应的CO2电流效率达到了50%.     

丙三醇在Pt电极上吸附和氧化过程的原位FTIR反射光谱研究

运用电化学循环伏安(CV)和原位FTIR反射光谱方法,研究了丙三醇在Pt电极上的氧化过程。结果指出,丙三醇的氧化是一个复杂的表面过程,其间包括脱水、吸附、解离等步骤.根据CV和红外实验数据,本文提出了Pt电极上丙三醇解离吸附的表面反应机理和不同电位下丙三醇氧化的分子过程。     

铂电极上苯和苯磺酸吸附定向的现场红外反射吸收光谱电化学方法研究

本文用现场红外反射吸收光谱电化学方法和循环伏安法研究铂电极上苯和苯磺酸的吸附定向.对于苯/铂势系,电势在-0.6至0.0 V(相对饱和甘汞电极)内,苯主要以垂直方式吸附;在0.0至0.8 V内则主要以平躺方式吸附.对于苯磺酸/铂体系,电势在-0.4至0.0 V内,苯磺酸分子中的苯环主要呈垂直吸附且SO_3H基团远离电极表面;在0.0至1.0 V内则主要以倾斜平躺方式吸附,SO_3H基团通过其中的两个氧原子吸附于电极表面上.     

铂电极上自组装铁原卟啉单分子层的表面增强振动光谱初探(英文)

应用现场表面增强拉曼光谱和衰减全反射表面增强红外光谱初步研究了0.1mol·L-1HClO4溶液中Pt电极表面铁原卟啉(FePP)自组装单层的电化学和结构特性.以514nm波长为激发线,得到了增强因子约为40的粗糙Pt电极上FePP在不同电位下的表面增强拉曼光谱.分析0.5～-0.3V(SCE)区间内谱峰变化,得到近似的吸附等温式,由此可估算出Fe3+/Fe2+的式量电位大约为-0.2V.原位表面增强红外光谱的测试结果表明,FePP分子主要以斜立方式吸附在Pt膜电极表面,其中一个环外羧酸根与电极表面相接触,而另一羧酸基团以氢键与相邻的FePP分子相连.这样的吸附结构在-0.1～0.9V(SCE)的电位区间内并没有显著的变化.     

In situ scanning FTIR microscopy and IR imaging of Pt electrode surface towards CO adsorption

In situ scanning FTIR microscopy was built up for the first time in the present work, which consists of an FTIR apparatus, an IR microscope, an X-Y mapping stage, and the specially designed electrochemical IR cell and computer software. It has been demonstrated that this new space-resolvd in situ IR technique can be used to study vibration properties of micro-area, and to perform IR imaging of electrode surface. The chemical image obtained using this technique fur CO adsorption on Pt electrode illustrated, at a space-resolution of 10~(-2) cm, the inhomogeneity and the distribution of reactivity of micro-area of electrode surface.     

In situ scanning FTIR microscopy and IR imaging of Pt electrode surface towards CO adsorption

In situ scanning FTIR microscopy was built up for the first time in the present work, which consists of an FTIR apparatus, an IR microscope, an X-Y mapping stage, and the specially designed electrochemical IR cell and computer software. It has been demonstrated that this new space-resolvdin situ IR technique can be used to study vibration properties of micro-area, and to perform IR imaging of electrode surface. The chemical image obtained using this technique for CO adsorption on Pt electrode illustrated, at a space-resolution of 10^-2 cm, the inhomogeneity and the distribu-tion of reactivity of micro-area of electrode surface. Project supported by the National Natural Science Foundation of China (Grant No. 29525307).     

纳米结构Pt膜方波电位法制备及特殊红外性能

运用方波电位法处理Pt微电极,制备一系列具有较高表面粗糙度的纳米结构薄膜.扫描隧道显微镜（STM）观察到薄膜由Pt金属岛组成,并测得所研制的薄膜虽然其平均厚度从58 nm 增加到139 nm,但Pt金属岛的平均尺度仅从102 nm增加到114 nm,而岛的平均高度也只在15～18 nm之间变化.以CO为探针分子,结合原位FTIR反射光谱研究,发现所制备的纳米结构薄膜上吸附态CO的红外吸收都给出类Fano光谱,初步归结为Pt金属岛的尺度效应.     

单分散PtNi纳米粒子特殊的红外光学性能(英文)

采用电位置换反应以及化学还原法制备了单分散PtNi纳米粒子,循环伏安结果显示该纳米粒子在0.1mol·L-1硫酸介质中对CO的氧化表现出比本体Pt电极更好的电催化活性.以CO为探针分子,采用电化学原位红外光谱研究了PtNi纳米粒子上的特殊红外光学性能.结果表明,PtNi纳米粒子无论是在玻碳电极还是在金电极上,均表现出对称的双极谱峰,同时给出很强的增强效应.论文研究结果有助于进一步了解低维纳米材料特殊红外性能的本质.     

Abnormal IR effects of Pt nanostructured surfaces upon CO chemisorption due to interaction and electron-hole damping

The abnormal IR effects (AIREs) characterized by a positive-going peak of platinum (Pt) nanostructured surface generated in a square-wave potential treatment upon CO molecule chemisorption was observed and analyzed with a consideration of the interparticle interaction and electron-hole damping between nanoislands and CO molecules. A theoretical simulation shows that the islanded nanostructured Pt surfaces, which gives rise to interparticle interaction, coupling with electron-hole mechanism, may contribute to the origins of positive-going peak (AIREs) observed by in situ Fourier transformation IR (FTIR) experiments.     

单分散PtNi纳米粒子特殊的红外光学性能

采用电位置换反应以及化学还原法制备了单分散PtNi 纳米粒子,循环伏安结果显示该纳米粒子在0.1mol·L^-1硫酸介质中对CO的氧化表现出比本体Pt 电极更好的电催化活性. 以CO为探针分子,采用电化学原位红外光谱研究了PtNi 纳米粒子上的特殊红外光学性能. 结果表明,PtNi 纳米粒子无论是在玻碳电极还是在金电极上,均表现出对称的双极谱峰,同时给出很强的增强效应. 论文研究结果有助于进一步了解低维纳米材料特殊红外性能的本质.     

CoPt nanoparticles and their catalytic properties in electrooxidation of CO and CH(3)OH studied by in situ FTIRS

CoPt nanoparticles supported on a glassy carbon electrode (denoted as CoPt/GC) were prepared by galvanic replacement reaction between electrodeposited Co nanoparticles and K(2)PtCl(6) solution. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were both employed to characterize the CoPt nanoparticles. It was shown that the CoPt nanoparticles have irregular shapes and most of them exhibit a core-shell structure with a porous Co core and a shell of Pt tiny particles. The composition of the CoPt nanoparticles was analyzed by energy-dispersive X-ray spectroscopy (EDX), which depicts a Co : Pt ratio of ca. 21 : 79. Studies of cyclic voltammetry (CV) demonstrated that CoPt/GC possesses a much higher catalytic activity towards CO and methanol electrooxidation than a nanoscale Pt thin film electrode. In situ FTIR spectroscopic studies have revealed for the first time, that a CoPt nanoparticles electrode exhibits abnormal IR effects (AIREs) for IR absorption of CO adsorbed on it. In comparison with the IR features of CO adsorbed on a bulk Pt electrode, the direction of the IR bands of CO adsorbed on the CoPt/GC electrode is inverted completely, and the intensity of the IR bands has been enhanced up to 15.4 times. The AIREs is significant in detecting the adsorbed intermediate species involved in electrocatalytic reactions. The results demonstrated a reaction mechanism of CH(3)OH oxidation on CoPt/GC in alkaline solutions through evidencing CO(L), CO(M), HCOO(-), CO(3)(2-), HCO(3)(-) and CO(2) as intermediate and product species by in situ FTIRS.     

In situ STM studies of electrochemical growth of nanostructured Ni films and their anomalous IR properties

We have extended the study of anomalous IR properties, which were initially discovered on nanostructured films of platinum group metals and alloys, to nanostructured films of nickel, a member of the iron group triad, and broadened the fundamental knowledge on this subject. Nanostructured thin films of nickel supported on glassy carbon [nm-Ni/GC(n)] were prepared by electrochemical deposition under cyclic voltammetric conditions, and the thickness of films was altered systematically by varying the number (n) of potential cycling within a defined potential range for electrodeposition. Electrochemical in situ scanning tunneling microscopy (STM) was employed to monitor the electrochemical growth of nanostructured Ni films. These in situ STM images illustrated that, along the increase of the film thickness, Ni films have undergone a transformation from layer structure to island structure and finally to lumpish arris structure. Investigations by in situ FTIR spectroscopy employing adsorbed CO as the probe revealed that these nanostructures of Ni films yield abnormal IR features, Fano-like IR features, and normal IR features, respectively. The IR bands of CO adsorbed on Ni thin films of a layer structure were inverted in their direction and enhanced in their intensity up to 15.5 times on an nm-Ni/GC(4) electrode. The Fano-like IR features, which are defined as a bipolar band with its negative-going peak on the low wavenumber side and its positive-going peak on the high wavenumber side, are observed for the first time on Ni thin films of an island nanostructure, i.e., at the nm-Ni/GC(16) electrode. IR features changed to normal absorption in CO adsorbed on the nm-Ni/GC(25) electrode, i.e., that with lumpish arris nanostructured Ni film of a larger thickness.     

CO和SCN~-在高分散Pt及Pd表面异常红外光学行为的电化学现场FTIR反射光谱研究

在玻碳基底上沉积Pt和Pd，在以CO和SCN-为探针分子的电化学现场FTIR反射光谱研究中，首次观察到异常红外光学行为，其中包括吸附物种的谱带方向倒反以及谱峰强度显著增强等．     

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.