Electrochemical promotion of catalytic reactions: Thermodynamic analysis and calculation of the limits in Faradaic Efficiency

In the past three decades, more than 70 catalytic systems have been reported to exhibit the NEMCA phenomenon (Non-Faradaic Electrochemical Modification of Catalytic Activity). NEMCA has been observed in O2 −, Na+, K+, Pb2 + and H+ conductors. As opposed to catalytic oxidations, however, in which dramatic increases in catalytic reaction rates have been observed, hydrogenation reactions exhibited weak NEMCA characteristics. The maximum Faradaic Efficiency (Λ) that can be obtained in a reaction with limited equilibrium conversion was calculated using a thermodynamic analysis. The values of Λ predicted by the present analysis are compared to those obtained experimentally during the reaction of NH3 synthesis in a H+ cell.