Electrochemical Methods for Catalyst Activity Evaluation

Since a fuel cell is an electrochemical device, electrochemical mefliods are deemed to play important roles in characterizing and evaluating the cell and its components such as the electrode, the membrane, and the catalyst. The most popular eleetroehemical characterization methods include potential step, potential sweep, potential cycling, rotating disk electrode, rotating ring-disk eleetrode, and impedance spectroscopy. Some techniques derived from these methods are also used for fuel cell characterization. 

An electrochemical reaction involves at least the following steps transport of the reactants to the surface of the electrode, adsorption of the reactants onto the surface of the electrode, charge transfer through either oxidation or reduction on the surface of the electrode, and transport of the product(s) from the surface of the electrode. The purpose of the electrochemical characterizations is to determine the details of these steps. 

In order to minimize the impact of the solution (or electrolyte) resistance on the potential of the working electrode, a reference electrode is often used to form another circuit with the working electrode. Ideally, this electrode is non-polarizable and maintains a stable potential. There is high input impedance in the voltage 

In this article, each section starts with a brief introduction to techniques, principles, and instrumentation, followed by examples for the purposes of illustration. The illustration is limited to low- to medium-temperature fuel cells such as the proton exchange membrane (PEM), direct liquid, and phosphoric acid fuel cells that involve protons as the ionic charge transport species. 

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Electrochemical Methods for Catalyst Activity Evaluation 597 11.8.2.2 Measurement of Fuel Crossover Rate... 

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