Although solid oxide fuel cell (SOFC) technology has been evolving over the past few decades, not much is known about the elementary electrochemical mechanisms that govern their performance. Molecular level insights on electrochemical reactions over SOFC electrodes is necessary to identify the critical elementary steps limiting SOFC performance and hence guide the development of better electro-catalytic materials for SOFCs. In this work, we present a first principles approach, combining density functional theory (DFT) calculations and statistical thermodynamics, aimed at studying electrochemical reactions over SOFC anodes incorporating effects of potential bias and electric field due to electrochemical double layer. We have utilized this approach to investigate several mechanisms for the electrochemical oxidation of hydrogen on various metal surfaces under solid oxide fuel cell operating conditions. We find that oxygen adsorption energy is an excellent descriptor for the electro-catalytic activity of different metals. Moreover we see that the electrochemical activity of metals, as a function of the oxygen adsorption energy, can be described with a volcano plot where weak oxygen-metal binding results in a high anode overpotential loss while highly exothermic interactions of oxygen and a metal surface result in the oxygen-induced poisoning of the electro-catalyst. Detailed results elucidating the thermodynamics of several reaction mechanisms on various metal surfaces will be presented.

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