Electrosorption on solid electrodes

In the early days of fimdamental studies of fuel cells, great efforts were made to develop direct-hydrocarbon fuel cells , light paraffin molecules such as propane and ethane, as well as unsaturated compounds such as ethylene were studies in this context The form in which hydrocarbons are adsorbed on platinum was the subject of controversy at the time, because it was assumed that it would influence the catalytic 

The only way ethane could form chemical bonds with the surfece is to break some C-H bonds, for example, according to.the equation  

This was called dissociative adsorption. If the potential is sufficiently positive with respect to the reversible hydrogen electrode in the same solution, the adsorbed hydrogen atoms will be ionized, and Eq. (13.6) can be rewritten as  

Replacing ethane by ethylene, the same type of dissociative electrosorption could take place, namely  

But there is an alternative route, referred to as non-dissociative ekctrosorption, which can be represented by the equation 

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