Electrocatalysis aqueous metal interface

The application of first principles methods to the study of electrocatalysis in fuel cells has gained significant momentum in recent years. Browse any issue of a journal with theoretical electrochemistry content and you will notice a few theoretical study articles. Theoretical modeling in electrochemistry has certainly reached the stage at which it can begin to complement experimental methods, and provide insight into the atomic scale features that control the chemistry at the aqueous/metal interface [101]. 

I. The parameter 2Fr0/Io ( A ) must be larger than unity (Chapter 4). Catalysis at the metal/gas interface must be faster than electrocatalysis. This is easy to satisfy in solid electrolyte systems and more difficult to satisfy in aqueous electrolyte systems. 

The rate constants for such outer-sphere reactions can therefore differ markedly from those corresponding to true weak-overlap pathways, even after correction for electrostatic double-layer effects. This can cause some difficulties with the operational definition of inner-sphere electrocatalysis considered above, whereby outer-sphere reactions are regarded as "non-catalytic processes. In addition, there is evidence that inner- rather than outer-sphere pathways can provide the normally preferred pathways at metal-aqueous interfaces for reactants containing hydrophobic functional groups [116]. 

In this chapter, we provide a succinct review of some of the advances in the development and application of ab initio methods toward understanding the intrinsic reactivity of the metal and the influence of the reactive site and its environment. We draw predominantly from some of our own recent efforts. More specifically we describe (a) the chemistry of the aqueous-phase on transition metal surfaces and its influence on the kinetics and thermodynamics within example reaction mechanisms, and (b) computational models of the electrode interface that are able to account for a referenced and tunable surface potential and the role of the surface potential in controlling electro-catalytic reactions. These properties are discussed in detail for an example reaction of importance to fuel cell electrocatalysis methanol dehydrogenation over platinum(ll 1) interfaces [24,25]. 

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