Characterization of Electrode Activity through Photoelectron Spectroscopy: A Coordinated Synchrotron and Laboratory XPS Approach to Electrocatalysis

该项目由分析和表面化学计划资助，解决了小分子氧化/还原反应的二元和三元电极催化剂的核心水平电子结合能位移和电催化反应性之间的相关性。该催化剂通过过渡金属在Pt、Ru、Pd和Au单晶衬底上的自发沉积形成。 有强有力的证据表明，admetals安排在二维和三维的nanosislands，在原位STM监测。这项工作是在伊利诺伊大学的Andrzej Wieckowski实验室和威斯康星大学麦迪逊分校的同步辐射中心（SRC）进行的;需要强烈的同步X射线光来测量低和非常低的admetal覆盖水平下的结合能变化。 此外，同步辐射的高分辨率使得结合能位移的精确测量成为可能。实验（Wieckowski UIUC，PI）和理论（Bagus UNT，co-PI）之间强大而直接的联系是该项目的关键要素，基本上决定了测得的核心能级结合能的化学和物理意义。 同步加速器的工作带来了高的X射线强度，高分辨率，和低检测水平的admetal覆盖。总体情况：电化学表征确定了反应性，同步加速器XPS和实验室XPS产生了结合能位移，并且理论提供了所研究表面的反应性和电子结构之间的定量联系。 这些电子水平的结果使人们了解过渡金属和贵金属双金属催化剂如何用于具有明确基础科学和应用意义的电催化反应。 所研究的材料在小分子燃料电池应用中显示出作为有效的氧化和还原催化剂的前景。因此，从这些基本调查中获得的信息可能有助于改进的燃料电池催化系统的设计。

This project, funded by the Analytical and Surface Chemistry Program, addresses the correlation between core level electron binding energy shifts and electrocatalytic reactivity at binary and ternary electrode catalysts for small molecule oxidation/reduction reactions. The catalysts are formed by spontaneous deposition of transition metals on single crystal substrates of Pt, Ru, Pd and Au. There is strong evidence that the admetals are arranged in two- and three-dimensional nanoislands, as monitored by in situ STM. This work is carried out in the laboratory of Andrzej Wieckowski at the University of Illinois and at the Synchrotron Radiation Center (SRC) at the University of Wisconsin-Madison; the intense synchrotron x-ray light is needed to measure the binding energy shifts at the low and very low admetal coverage levels. Moreover, the high resolution of the synchrotron radiation makes possible accurate measurements of the binding energy shifts. A strong and direct link between experiment (Wieckowski UIUC, PI) and theory (Bagus UNT, co-PI) is a key element of this project that basically determines the chemical and physical significance of the measured core level binding energies. The synchrotron work brings high x-ray intensity, high resolution, and low detection level for the admetal coverage. Overall: electrochemical characterization determines reactivity, synchrotron XPS and laboratory XPS yield the binding energy shifts, and theory provides quantitative link between the reactivity and electronic structure of the studied surfaces. These electronic-level results produce understanding of how transition and noble metal bimetallic catalysts work for electrocatalytic reactions of clear basic-science and applied significance. The materials studied show promise as effective oxidation and reduction catalysts in small molecule fuel cell applications. Therefore, information obtained from these fundamental investigations may aid in the design of improved fuel cell catalytic systems.