Permanent Electrochemical Promotion for Environmental Applications

L. LIZARRAGA; P.VERNOUX

Encyclopedia of Applied Electrochemistry

Springer-Verlag

Lugar: Berlin; Año: 2013; p. 1 - 7

Electrochemical Promotion of Catalysis (EPOC), or Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) effect, is a promising concept for boosting catalytic processes and advancing the frontiers of catalysis. This innovative field aims to modify both the activity and the selectivity of catalysts in a controlled manner. EPOC utilizes solid electrolyte materials as catalytic carriers. Ions contained in these electrolytes are electrochemically supplied to the catalyst surface and act as promoting agents to modify the catalyst electronic properties in order to achieve optimal catalytic performance. EPOC can be considered as an electrically controlled catalyst-support interaction in which promoting ionic agents are accurately supplied onto the catalytic surface by electrical potential control. The main advantage of EPOC is that the electrochemical activation magnitude is much higher than that predicted by Faraday?s law. Therefore, EPOC requires low currents or potentials. Moreover, promoting species such as O2- and H+ cannot be formed via gaseous adsorption and cannot be easily dosed by chemical means. EPOC has been investigated thoroughly for more than 70 catalytic reactions [1, 2] and is reversible, since the catalyst restores its initial activity, typically within a few minutes after current interruption. Recently, however, some studies have shown that, for specific operating conditions and catalyst-electrodes, the reversibility of this phenomenon strongly depends on the duration of the polarization. For prolonged polarization times, the catalytic reaction rate after current interruption can remain higher than the value before current application [3]. This behavior has been reported as ??permanent-electrochemical promotion of catalysis? (P-EPOC). This phenomenon was mainly observed over catalysts which have multiple valence states and the ability to form oxides, i.e., Pt /PtOx or Rh/Rh2O3.