Spectroscopy as a Probe of Surface Electrochemistry at Metal Catalyst Particles

Infrared Spectroscopy as a Probe of Surface Electrochemistry at Metal Catalyst Particles 

An area of increasing importance is the study of surface electrochemistry at nanometer-scale metal catalyst particles. An effective approach for applying in-situ infrared spectroscopy has been to adsorb catalyst onto the surface of a metal substrate that is highly reflective and also inert over the potential range of interest [15, 17, 155-161]. PolycrystaUine Au electrodes have been employed fre- 

7 Recent Advances in in-situ Infrared Spectroscopy and Applications 

The Au substrate was immersed in a solution of 3-mercaptopropyltrimethoxysilane (3-MPTS) to produce a self-assembled monolayer (SAM). The film was cross-linked 

Results of the Maillard study [19] additionally suggested that barriers to CO diffusion existed between particles on the carbon support. Hence, CO molecules could become trapped on small particles, being unable to reach active sites on the 3.6-nm Pt. In their pioneering work. Weaver and coworkers also observed spectral features and reactivity behavior dependent upon the size of Pt deposits on carbon-supported catalyst materials [17, 160]. Working with homogeneous particle size distributions, they showed that responses typical of low-coordination surface atoms become dominant for Pt particles smaller than about 4 nm 

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