Surface Structure Effects in Dissociative Adsorption Kinetics and Electrocatalytic Oxidation of Ethylene Glycol

本文选题研究乙二醇（EG）分子在铂单晶电极上吸附和氧化的表面过程和反应动力学，涉及电催化、表面科学、能源科学（直接燃料电池）等学科前沿。金属单晶面具有明确的表面原子排列结构，对于深入认识表面结构与性能的内在联系和规律，在微观层次发展电催化理论等方面具有重要意义。我们研制了(100),(110),(111),(311),(511),(711),(911)和(751)等8个Pt单晶面，运用电化学循环伏安、程序电位阶跃技术和原位FTIR反射光谱等方法，研究了EG在这8个Pt单晶电极上的解离吸附和氧化反应动力学，取得的主要原创性结果如下：(1)发现EG的解离吸附反应是表面结构敏感的过程，不同表面原子排...Electrocatalytic oxidation of small organic molecules is of fundamental importance in electrocatalysis. This thesis put emphasis upon studies of surface process and reaction kinetics of ethylene glycol (EG) adsorption and oxidation on Pt single crystal electrodes. The subject presents a frontier of multidiscipline covering electrocatalysis, surface science and energy science (direct fuel cell). Si...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：B20012501

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

Pt单晶(210)、(310)和(510)阶梯晶面上CO_2电催化还原的表面过程

研究Pt单晶(210)、(310)和(510)三个阶梯晶面上CO_2电催化还原的表面过程.通过改变处理条件获得单晶电极不同的表面结构.研究结果指出,当铂单晶电极表面保持其确定原子排列结构时,对CO2还原的电催化活性随晶面上(110)台阶密度的降低而减小,即Pt(210)>Pt(310)>Pt(510);当三个电极表面发生氧的吸附导致原子排列结构重建时,其电催化活性均有不同程度的提高.虽然其活性顺序未发生变化,但(110)台阶位密度越大的表面其电催化活性增加的程度越高.研究指出Pt单晶电极的表面结构越开放,其电催化活性也越高,并且在外界条件诱导下更易于转变为具有更高反应活性的表面结构.而相对有序的表面结构则比较稳定.研究结果从微观层次获得CO2与Pt单晶电极表面相互作用的规律,深化了对CO2电催化还原表面过程的认识.国家自然科学基金(批准号:20673091,20433060,20373059);; “973”计划(批准号:2002CB211804)资助项

Pt(100)电极上乙二醇吸附和氧化的原位时间分辨FTIRS研究

运用原位时间分辨FTIR反射光谱在分子水平研究乙二醇(EG)在Pt(100)单晶电极上吸附和氧化的动力学过程.在0.10V的时间分辨光谱中,当t>5s于2050cm?1附近出现的红外谱峰归因于EG解离吸附产物线性吸附态CO(COL)的红外吸收.红外光谱特征及其变化还证实,吸附态CO在Pt(100)表面呈均匀分布;当t>70s于2342cm?1附近出现CO2的不对称伸缩振动谱峰,指认为EG的直接氧化.研究发现随着电位升高,直接氧化逐渐成为主要反应途径,使解离吸附反应削弱.当电位高于0.40V以后,EG的氧化主要通过活性中间产物(–COOH)的途径进行

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

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 (v(i)) 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 SO42-/HSO4-). We illustrate that the variation of the average reaction rate (v) over bar 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

Rare Earth Eu Doped PtRu/C Catalysts and Their Properties for Methanol Electrooxidation

Corresponding authors. Email: [email protected], [email protected]; Tel: +86-773-5846279, +86-592-2180181.[中文文摘]采用化学还原和热处理方法对商业PtRu/C催化剂进行稀土Eu掺杂,制备了不同Eu含量的PtRuEux/C催化剂.透射电子显微镜(TEM)、X射线能量色散光谱(EDX)、X射线衍射(XRD)和X射线光电子能谱(XPS)等方法表征催化剂的结果表明,Eu的掺杂未改变PtRu/C催化剂的平均粒径(约为3nm),并且Eu以金属和氧化物两种形态修饰PtRu表面.循环伏安和计时电流法测试显示,PtRuEux/C催化剂较商业PtRu/C对甲醇氧化具有更高的活性,其中PtRuEu0.3/C的活性最高.运用原位傅里叶变换红外(FTIR)光谱从分子水平研究了该催化剂对甲醇电催化氧化的反应过程,检测到甲醇在催化剂上解离吸附的吸附态产物是线型吸附态CO(COL),Eu的掺杂使COL的氧化电位降低,明显提高了催化剂的活性和抗CO毒化的能力.[英文文摘]Commercially available PtRu/C catalyst was doped with Eu by chemical reduction and sintering, resulting in PtRuEux/C catalysts with different Eu contents. The catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results showed that Eu doping did not change the average size of the PtRu/C catalysts (ca 3 nm), and their surfaces were modified by both Eu metal and oxide. Cyclic voltammetry and chronoamperometry demonstrated that the activity of the PtRuEux/C catalysts was higher than that of commercial PtRu/C for methanol electrooxidation. Among the PtRuEux/C catalysts, PtRuEu0.3/C exhibited the best performance. The electrocatalytic oxidation of methanol on the catalyst was further investigated by in situ Fourier transform infrared (FTIR) spectroscopy at molecular level. Results indicated that the adsorbed species derived from the dissociative adsorption of methanol on the catalysts were linear-bonded CO (COL). Eu doping decreased the oxidation potential of COL and thus significantly enhanced the activity of the catalysts and their tolerance to CO.国家自然科学基金(20833005,20828005);教育部留学回国人员科研启动基金; 厦门大学固体表面物理化学国家重点实验室开放课题;广西研究生教育创新计划项

Electrodeposition of Lanthanum in Deep Eutectic Solvents

以氯化胆碱/尿素低共熔溶剂为介质通过恒电位沉积法成功制备了形状和尺寸均一的橄榄状镧粒子.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)和X射线光电子能谱(XPS)等技术对所制备的样品进行表征.同时,研究了沉积电位、温度和时间等因素对样品尺寸、形貌的影响,确定恒电位法制备橄榄状镧粒子的工艺优化条件为沉积电位-1.7 V、温度80oC和沉积时间15 min.With the choline chloride/urea deep eutectic solvents(DESs) as the medium, the olive-like lanthanum particles with uniform shape and size were successfully prepared through a potentiostatic deposition method. The prepared samples were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy dispersive X-ray(EDX) spectroscopy and X-ray photoelectron spectroscopy(XPS). At the same time, the effects of deposition potential, temperature and time on the size and morphology of samples were investigated. The results demonstrated that the optimum conditions for the preparation of olive-like lanthanum particles were as follows: deposition potential of-1.7 V, temperature of 80 oC and deposition time of 15 min.国家自然科学基金项目(No.21463007;No.21263002);; 厦门大学固体表面物理化学国家重点实验室开放课题(No.201305);; 广西自然科学基金项目(No.2013GXNSFAA019024);; 广西教育厅科学技术研究项目(No.2013YB026)资

Kinetics of Dissociative Adsorption of Ethylene Glycol on Pt(111) Electrode

运用电化学循环伏安和程序电位阶跃方法研究了乙二醇在Pt(111)单晶电板上的解离吸附过程,动力学研究的定量结果指出,乙二醇解离吸附反应的平均速率v随电极电位变化呈火山型分布,其最大值在0.10V(vsSCE)附近.测得在含2×10-3mol·L-1乙二醇的溶液中,最大初始解离速率V1为4.35×10-12mol·cm-2·S-1.The dissociative adsorption of ethylene glycol (EG) on Pt(111) electrode has been investigated with electrochemical cyclic voltammetry and programmed potential step technique. The quantitative results demonstrated that the average rate of dissociative adsorption of ethylene glycol on Pt(111) electrode depends on electrode potentials, yielding a distribution of volcanic shape on adsorption potentials between - 0. 20 and 0. 35 V with the maximum value of 3. 90×10-12 mol·cm-2·s-1 located near 0. 10 V(vs SCE). From the variation of the quantity of dissociative adsorbates determined through the oxidation charge with adsorption time (tad), the initial rate (vi) of this surface reaction has been evaluated quantitatively. The maximum of vi was ascertained to be 4. 35×10-12 mol·cm-2·s-1 at 0. 10 V for a solution containing 2·10-3 mol·L-1 EG.国家自然科学基金(20373059,90206039);; 教育部科学技术重点研究基金资助项目~