Electrocatalyst isotherms

Electrocatalyst see also specific catalysts adsorbate-support interactions, 30 273-279 adsorption, 30 240-264 isotherms, 30 241-243 bimetallic activity, 30 275... 

Reaction or exchange with stable isotopic tracers and quantitative identification of all products by mass spectrometry provides indications for molecular interactions on the surface. Reactions can be studied at steady state or by following the transient distribution of isotopic products. Langer and co-workers (25,26) presented the first steady-state mechanistic analysis for the electrocatalytic hydrogenation of ethylene on Pt in deuterated electrolytes. Proton abstraction in electroorganic synthesis has also been verified using deuterated solvents (374, 375). On-line mass spectrometry permitted indirect identification of adsorbed radicals in benzene and propylene fuel cell reactions (755,795,194). Isotopic radiotracers provided some notion on adsorption isotherms (376, 377) and surface species on electrocatalysts (208, 378, 379). 

Adsorption of more than one species and complex electrocatalytic surface reactions [Eqs. (10) and (16)] may result in nonunique steady-state operation and in current or potential oscillations (31, 78, 417). We examined recently conditions for isothermal multiple steady states at planar, and porous, flow-by or flow-through electrocatalysts (418). 

The same complex kinetics gives multiple steady states isothermally in thin or thick porous electrocatalysts (418). A simple, graphical orthogonal collocation method (422) can show the existence of multiple solutions for concentration within a certain potential range (418). If ohmic losses in the pores cause a potential change within the electrode structure, multiplicity can also arise with respect to potential, even with simpler rate expressions... 

Ma et al. studied the adsorption of NAFION on electrocatalysts and the supporting carbons in aqueous solution by F NMR, revealing that NAFION adsorbs strongly on carbon as well as noble metal electrocatalysts Pt and PtRu. At low concentration, the adsorption was found to follow a Langmuir isotherm [210]. 

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