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 )~

Electrochemical Preparation and Particular IR Properties of Nanostructured Island Films——Surface Combinatorial Studies by Combining Individually Addressable Microelectrode Array with in situ Microscop

Pt、Ru、Pd、Rh等铂族金属以及它们的合金通常具有良好的催化性能，作为催化剂材料被广泛地应用于能源转化、绿色合成等重大领域。具有纳米结构、纳米尺度的铂族金属纳米材料往往表现出更优异的催化性能从而备受关注。纳米材料的性能与其结构密切相关。因此深入研究纳米材料的结构与性能之间的内在联系与规律，对于揭示其特殊性能的本质、进一步优化和提高纳米材料的性能等方面具有深刻的意义。本研究小组采用电化学循环伏安电沉积法在GC基底上制备层状纳米结构金属薄膜，以CO作为分子探针，观察到异常红外效应（AIREs）光谱特征，即CO等探针分子发生红外吸收增强、红外谱峰方向倒反（反吸收）和谱峰变宽（振动能级离散程度增加...Platinum group metals and their alloys have been extensively employed in energy conversion and green synthesis as electrocatalysts owing to their high catalytic activity. Pt group metals at nanometer scale have attracted much attention worldwide because of their higher catalytic activity and better properties. It is well known that the properties of nanomaterials depend strongly on their nanostruc...学位：理学博士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：B19992501

阵列Pt微电极上CO吸附的原位显微FTIR反射光谱研究

研制了Ｐｔ微电极阵列，运用电化学原位显微ＦＴＩＲ反射光谱研究ＣＯ吸附的性能．发现经快速电位循环扫描处理可以在Ｐｔ微电极表面上产生一种纳米结构薄层，吸附在薄层表面ＣＯ的红外吸收给出谱峰方向倒反和强度显著增强的异常红外特征

Electrochemical In Situ Step-scan Time-resolved Microscope FTIR Spectroscopy

结合步进扫描傅立叶变换红外光谱仪和红外显微镜,建立了电化学原位步进扫描时间分辨显微镜FTIR反射光谱.采用微电极和利用纳米结构表面的异常红外效应,显著提高表面吸附物种的红外检测灵敏度和红外电极表面对极化电位的响应速度,使广泛应用的外反射型薄层红外电解池的时间常数(τ=R1Cd)从使用常规盘电极的约40ms降低到0.65ms.研究了酸性介质中CO在Pt电极上的吸附过程,谱图的时间分辨率达50μs.Electrochemical in situ step-scan t ime-resolved microscop e FTIR spectroscopy(in situ SS-TR-MFTIRS )was succes sively established,for t he first time in the present work,by u sing a step-s can FTIR in-strument (Nexus 870FTIR spectrometer)and an IR microscope(IR-plane advantage microscope).A homemade signal synchronizer was used to gener ate polarization potential that is in accordance with the signal-time-sequence of step-scan time-resolved spectra l data collection.Due to the use of a n a nostructured microelectrode of Pt and the enhancement of IR absorption,a chara cter of abnormal infrared effects o f the nanostructured Pt surface,IR d e-ter mination sensitivity of surface species was significantly increase d,and the ra te of responding to a pola rizing potential of electrode surface in a t hin-lay er IR cell was remarkably imp roved.Adsorption of CO on nanostruc-tured Pt mic roelectrode(?=0.2mm)in sulfuric acid solutions was investigated by using the present new tech-nique,and a spectral time-resolution as fast as 50ìs has been achieved.From the variation versus t of the band center of linear-bon ded CO(see Fig.7)that is measured from in situ SS-TR-MFTIR spectra,the ce ll constant (?=R l C d )of an electrochemical thin-layer IR cel l of external reflection mode,wh ich is employed widely in studies of electrochemical in situ IR spectroscopy,ha s been determined to be 0.65ms.In comparison with the?of 40ms for a conv entional Pt disk ele ctrode(?=6.0mm),the use of a Pt microelectrode has re duced dra-matically the thin-layer IR cell constant to about 61times.The results o btained in the current paper is of im-portance in illustrating the s uccess of establishing the in situ SS-TR-MFTIRS,and demonstrating th e powerf ul capability of the in situ SS-TR-MFTIRS for studies of fast dynamic process es of electrode and kinetics of reac-tions taking place at solid /liquid i nte rfaces as well.教育部科学研究基金(29833060,20021002);; 国家自然科学基金(20023001

In Situ FTIR Spectroscopy Studies of HCOOH Oxidation on Surface Alloy Electrocatalysts

运用原位红外反射光谱(FTIRS)和电化学循环伏安法(CV)研究了甲酸在三种不同电极上的电催化特性。结果表明甲酸在碳载铂电极(Pt/GC)上的电催化氧化机理与本体铂电极(Pt)相类似,即可以通过活性中间体或毒性中间体氧化至CO_2。Pt/GC对甲酸的氧化比Pt具有更高的电催化活性。Pt/GC表面以Sb吸附原子修饰的电极(Sb-Pt/GC)上,甲酸氧化的起始电位(E;)提前至-0.10V,氧化电流峰电位(Ep)提前至0.34V,氧化峰电流(jp)值增加了7.28倍,半峰宽(FWHM)为0.30V。同样,Surface al-loy/GC电极上,E_I为-0.12V,E_p为0.32V和j_p为7.25mA·cm~(-2),相对Pt/GC分别负移了0.22,0.02V和增大了8.15倍,半峰宽(FWHM)为0.5V。表明Sb-Pt/GC和Surface alloy/GC电极不仅能够有效地抑制毒性中间体CO的生成,而且还可以显著地提高其对活性中间体的氧化的电催化活性。Electrocatalytic properties of three electrodes for formic acid oxidation were studied by using electrochemical in situ FTIR spectroscopy and cyclic voltammetry in this paper. It is demonstrated that the electrocatalytical mechanism of formic acid oxidation on platinum-dispersed carbon(Pt/GC) is similar to that on massive platinum, which involves two paths, i. e. one way through active intermediate and the other through poison intermediate to CO2. The Pt/GC exhibits higher catalytivity than pure platinum. The electrode of Pt/GC modified by Sb (Sb-Pt/GC)was also prepared in the work. It was observed that the onset potential (Ei) for formic acid oxidation on Sb-Pt/GC was shift negatively for 0.20 V. The peak potential (Ep.) was observed to shifted negatively to 0.34 V and the value of oxidation current (jf) was enhanced nearly 7.28 times. Similar results were also observed on surface alloy/GC prepared. In this case, Ei and Ep were -0.12 and 0.32 V,respectively, jp was enhanced about 8.15 times,and FWHM (full width at half maximum) was 0.50 V. It is indicated that Sb-Pt/GC and surface alloy/GC can not only effectively restrain the formation of poison intermediate CO, but also significantly increase the electrocatalytic activities for oxidation of active intermediates.厦门市科技攻关项目基金(3502E2001);; 福建省自然科学基金(E9910003);; 国家自然科学基金(20021002,90206039

Solid/Liquid Interfacial In Situ IR Microscope and Step-Scan Time-Resolved FTIR Spectroscopy and Applications in Studies of Nanomaterials

结合红外显微镜和步进扫描FTIR光谱仪 ,发展了固 /液界面电化学原位显微镜红外反射光谱和步进扫描快速时间分辨FTIR反射光谱 ,并应用于纳米材料特殊性能和电化学反应动力学的研究。研制纳米结构Pt微电极 ,获得CO吸附的红外特征随纳米结构和纳米尺度变化的原位显微镜红外谱图。利用纳米结构Pt微电极的异常红外效应 ,显著提高电化学原位红外反射光谱的灵敏度 ,获得分辨率达 5 0 μs的步进扫描时间分辨光谱。不仅发展了固 /液界面显微镜原位红外反射光谱新方法 ,并且拓展了电化学原位红外反射光谱在纳米材料科学研究中的应用。Electrochemical in situ microscope IR reflection spectroscopy and step-scan time-resolved FTIR reflection spectroscopy were established by using an IR-plan advantage microscope and a Nexus 870 FTIR instrument, and a home-made signal synchronizer that harmonizes electrode polarization potential and step-scan spectral data collection sequence. These new techniques have been applied in studies of particular IR properties of 2-dimensional nanomaterials. By applying a treatment of fast potential cycling with different time (τ), a set of nanostructured Pt microelectrodes were prepared. CO adsorption was employed as a probe reaction together with in situ developed microscope FTIR spectroscopy. The results illustrated the variation of abnormal IR features with the nanostructure and the thickness (i.e., the size) of film formed on Pt microelectrode, i.e., following the increase of τ in fast potential cycling treatment, the direction of CO band was turned from absorption to antiabsorption direction, and the intensity and the width of CO band were increased. By taking the advantage of the abnormal infrared effects of nanostructured Pt microelectrode, the sensitivity of in situ IR reflection spectroscopy has been significantly improved, and spectra of time-resolution as fast as 50 μs have been recorded at solid/liquid interfaces. The current studies demonstrated not only the success of development of new techniques of in situ IR spectroscopy, but also the exploitation of the established techniques in studies of nanomaterials.国家自然科学基金 (2 0 0 2 1 0 0 2 ,90 2 0 60 39);; 教育部科学研究基金 (0 1 1 0 1 )资助项