1 research outputs found
Spatial Mapping of Methanol Oxidation Activity on a Monolithic Variable-Composition PtNi Alloy Using Synchrotron Infrared Microspectroscopy
The
use of synchrotron-sourced infrared radiation to map the electrochemical
activity of a binary metal (Pt and Ni) alloy is demonstrated. The
alloy is created in such a way that its metal concentration varies
along one of its dimensions thus creating a continuum of electrocatalyst
compositions on a single electrode. Localized methanol oxidation activity
is determined spectroscopically by measuring the rate of CO<sub>2</sub> production at variable positions along the alloy concentration gradient
using an infrared microscope. Numerical simulations of the kinetically
controlled reaction demonstrate that qualitative assessment of relative
reaction rates is possible as long as the reaction is followed on
time scales smaller than those that lead to diffusional broadening.
Characterization of the alloy before and after electrochemical experiments
reveals significant levels of base metal leaching. Highly dealloyed
regions of the sample show the highest rates of methanol activity
and have a final Ni atomic composition of approximately 5%. Surface
roughening from the dealloying process is shown to be at least partially
responsible for enhanced activity