ABSTRACT
ABSTRACT X-ray absorption spectroscopy (XAS) is a very powerful technique for the study of carbon-supported Pt and Pt alloy electrocatalysts. Because of the penetrating nature of x-rays, it is possible to do in situ measurements under electrochemical conditions. A major advantage of XAS in the study of electrocatalysts is its ability to probe the d states of Pt catalysts. The element specific nature of the probe permits the study of the chemical environment around individual components in alloy catalysts. An interesting aspect of carbon-supported Pt and Pt alloy electrocatalyst particles is the large ratio of surface to bulk atoms. Typically, between 30 and 50% of the atoms are surface atoms. This factor is key to the application of XAS to catalysts. XAS is basically a bulk spectroscopy, so having a large fraction to the surface atoms that are exposed to the x-rays contributing to the electrocatalysis is key to getting information on the catalytic process. This chapter reviews x-ray absorption studies on carbon-supported Pt and Pt alloy electrocatalysts. In addition, the chapter discusses the methods of preparation and the properties of these catalysts. In the case of XAS, descriptions are given for sample preparation, spectroelectrochemical cells, and the methodology of data acquisition and analysis.
