Ab. Anderson et E. Grantscharova, POTENTIAL DEPENDENCE OF CO(ADS) OXIDATION BY OH(ADS) ON PLATINUM ANODES - MOLECULAR-ORBITAL THEORY, Journal of physical chemistry, 99(22), 1995, pp. 9143-9148
An atom superposition and electron delocalization molecular orbital (A
SED-MO) study has been made of the electrochemical oxidation of the CO
poison on the Pt anodes that is generated during methanol fuel cell o
peration. The interaction of CO(ads) with the oxidant OH(ads) is shown
to be productive only at high surface coverages, as high coverages ac
tivate CO(ads) by weakening its bond to the surface. The potential dep
endence of this reaction, modeled by shifting the metal valence band p
arametrically, has the wrong behavior for it to be the rate-limiting s
tep. A rate-limiting step which has good qualitative agreement with me
asured apparent activation energies at different potentials is the gen
eration of OH(ads) from H2O(ads), for which the activation energy barr
ier is calculated to decrease as the potential increases.