Anode hydrogen-diffusion

Cabot PL, Centelles M, Segarra L, Casado J. Palladium-assisted electrode-halogenation of l,l,2-trichloro-l,2,2-trifluoroethane on lead cathodes combined with hydrogen diffusion anodes. J Electrochem Soc 1997 144 3749-3757. 

Cabot, P.L., Segarra, L. and Casado, J. (2004) Electrodegradation of chlorofluorocarbons in a laboratory-scale flow cell with a hydrogen diffusion anode. J. Electrochem. Soc. 151, B98-B104. 

The oxidation of hydrogen to protons as anode reaction is conceptionally attractive, and the use of a hydrogen diffusion anode should be considered in more cases of electroorganic reductions than has been done until now [68-73]. 

Hydrogen diffusion anodes utilized in practical fuel cells are technical electrodes. In this kind of electrodes, complications arise from the undefined structure of the catalyst. Furthermore, most of the surface analytical methods used with smooth surfaces can not be applied with highly dispersed technical electrodes. That is the reason because, traditionally, HOR has been studied in model electrodes, used to reduce complexity and to simplify interpretation of electrochemical experiments. For example, in model electrodes there is no influence of gas flow nor effect of the ionomer, as would be the case for a technical electrode measurement. Besides, another motivation to woik with model electrodes lies in the preparation of defined structures, like well-defined surfaces. In this scenario, the relationship between electronic property and electrochemical reactivity m be evident in the experimental measurements. 

In order to provide particularly low anode overpotentials, a recent development has been the use of hydrogen diffusion anodes. Hydrogen gas is continuously passed through a porous, catalytic anode matrix, to facilitate hydrogen oxidation. Hydrogen anodes have already been introduced into some zinc electrowinning tank houses. 

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