Surface structure effects in electrocatalysis of CO2 reduction on Pt single crystal and Sb modified planes

CO2的电催化还原是环境科学，能源科学，电化学等研究领域的前沿课题。金属单晶电极具有明确的表面原子排列结构，为认识界面微观结构，电催化反应的表面过程提供了一个理想模型。两者结合不仅把CO2还原反应的研究从宏观唯象推进到表面微观过程，而且为在微观层次设计、筛选和研制高性能电催化剂提供指导。 本论文研制了Pt(100)、Pt(110)、Pt(111)、Pt(510)、Pt(310)、Pt(210)、Pt(320)和Pt(991)等八个Pt单晶电极，并通过表面处理获得同一电极的不同表面结构，运用电化学循环伏安方法（CV），程序电位阶跃暂态技术和原位FTIR光谱，研究了在上述不同表面结构的Pt单晶电...Electrochemical reduction of CO2 is closely related to environment, energy and eletrocatalysis. Single crystal electrodes can provide well-defined surface structure of atomic arrangement, which have been used as model electrocatalysts to study the intrinsic structure function relationship of electrocatalysis. The study of electrocatalytic reduction of CO2 on Pt single crystal electrodes can reveal...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：B20042505

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

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~

Adsorption and Oxidation of Glycine on Au Film Electrodes in Alkaline Solutions

运用原位红外反射光谱(insituFTIRS)和电化学石英晶体微天平(EQCM)在分子水平上研究了碱性介质中甘氨酸在纳米金膜电极上的解离吸附和氧化过程.结果表明,甘氨酸在很低的电位下(-0.8V,vsSCE)就可发生解离吸附.其解离产物氰基(CN-)与电极表面存在较强的化学吸附作用,形成AuCN-物种(红外吸收谱峰位于2100cm-1附近).吸附在纳米金膜表面的CN-给出红外吸收显著增强、红外谱峰方向倒反和半峰宽增加的异常红外效应特征.吸附态CN-在低电位抑制H2O和OH-的吸附,当电位高于0.2V可氧化产生OCN-;进一步升高电位到0.3V则形成Au(CN)-2.溶液相物种OCN-和Au(CN)-2对应的红外吸收峰分别为2169cm-1和2145cm-1.实验结果指出,金以Au(CN)-2的形式溶解是导致电极表面质量显著减少的主要原因.Adsorption and oxidation of glycine on electrodes of nanometer scale thin film of gold in alkaline solutions were investigated using in situ FTIR reflection spectroscopy and electrochemical quartz crystal microbalance(EQCM). The FTIRS results demonstrate that the dissociative adsorption of glycine on Au surface can occur at potentials as low as -0.8 V(vs SCE), which leads to produce adsorbed CN- species (cyanide, ～2100 cm-1). When electrode potential is higher than 0.2 V, the adsorbed CN- can be oxidized to OCN-(cyanate, 2169 cm-1); and when the potential is increased further up to 0.3 V, the species(gold di cyanide, 2145 cm-1)appeared as further oxidative species. It has revealed that the electrodeposited nanometer scale thin film of gold on glassy carbon substrate(nm Au/GC) exhibited AIREs(abnormal infrared effects) for CN- adsorption, which manifested 3 nonlinear IR spectra features: the inversion of the direction of CN- IR band, the enhancement of IR absorption of CN-(about 20 folds) and the increase in the FWHM(full width at half maximum) of CN- IR band. According to EQCM results,the CN- species can adsorb strongly on Au surface and therefore inhibit the adsorption of H2O and OH- species in low potential region. The formation of was determined to be the main reason which caused the dramatic loss of surface mass of Au film electrode in a potential scan up to 0.6 V. The current studies are of importance in understanding the interaction between amino acids and Au film electrodes.国家自然科学基金(20021002,90206039,20023001);; 教育部科学研究基金资助项目

Cyclic Voltammetry and in situ FTIR Studies of Cyanide Adsorption on Nanostructured Au Film Electrode in Alkaline Solutions

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.The adsorption of cyanide(CN-) on electrodes of nanometer scale thin film of gold supported on glassy carbon(nm-Au/GC) in alkaline solutions were investigated using cyclic voltammetry and in situ FTIR spectroscopy.It has revealed that the electrodeposited nanostructured Au thin film exhibited AIREs(abnormal infrared effects) for CN-adsorption,which manifested 3 nonlinear IR spectral features: inversion of the direction of CN-band,enhancement of IR absorption of adsorbed CN-species(about 39.2 folds) and increase in the FWHM(full width at half maximum) of CN-band.作者联系地址：厦门大学化学化工学院化学系固体表面物理化学国家重点实验室,厦门大学化学化工学院化学系固体表面物理化学国家重点实验室,厦门大学化学化工学院化学系固体表面物理化学国家重点实验室 福建厦门361005,福建厦门361005,福建厦门361005Author's Address: Department of chemistry,College of Chemistry and Chemical Engineering,State Key Laboratory of PhysicalChemistry of Solid Surfaces,Xiamen University,Xiamen 361005,Fujian,Chin

Adsorption and oxidation of glycine on Au film electrodes in alkaline solutions

Adsorption and oxidation of glycine on electrodes of nanometer scale thin film of gold in alkaline solutions were investigated using in situ FTIR reflection spectroscopy and electrochemical quartz crystal microbalance(EQCM). The FTIRS results demonstrate that the dissociative adsorption of glycine on Au surface can occur at potentials as low as -0.8 V ( vs SCE), which leads to produce adsorbed CN- species (cyanide, 2 100 cm(-1)). When electrode potential is higher than 0.2 V, the adsorbed CN- can be oxidized to OCN- (cyanate, 2169 cm(-1)); and when the potential is increased further up to 0.3 V, the Au(CN)(2)(-) species (gold di-cyanide, 2145 cm(-1))appeared as further oxidative species. It has revealed that the electrodeposited nanometer scale thin film of gold on glassy carbon substrate (nm-Au/GC) exhibited AIREs(abnormal infrared effects) for CN- adsorption, which manifested 3 nonlinear IR spectra features: the invenrion of the direction of CN- IR band, the enhancement of IR absorption of CN-(about 20 folds) and the increase in the FWHM (full width at half maximum) of CN- IR band. According to EQCM results, the CN- species can adsorb strongly on Au surface and therefore inhibit the adsorption of H2O and OH- species in low potential region. The formation of Au(CN)(2)(-) was determined to be the main reason which caused the dramatic loss of surface mass of Au film electrode in a potential scan up to 0.6 V. The current studies are of importance in understanding the interaction between amino acids and Au film electrodes

快重离子辐照引起Ni/SiO_2界面原子混合及相变研究

在室温下用308 MeV的Xe离子和853 MeV的Pb离子辐照Ni/Si O2样品,用卢瑟福背散射和X射线衍射技术对样品进行了分析。通过分析Ni/SiO2样品中元素成分分布和结构随离子辐照剂量和电子能损的变化,探索了离子辐照在Ni/SiO2样品中引起的界面原子混合与结构相变现象。实验结果显示,Xe和Pb离子辐照均能引起明显的Ni原子向SiO2基体的扩散并导致界面附近Ni,Si和O原子的混合。实验观测到低剂量Xe离子辐照可产生NiSi2相,而高剂量Xe离子辐照则导致了Ni3Si和Ni O相的形成。根据热峰模型,Ni原子的扩散和新相的形成可能由沿离子入射路径强电子激发引起的瞬间热峰过程驱动

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel