1 Department of Energy Conversion and Storage, Technical University of Denmark 2 Applied Electrochemistry, Department of Energy Conversion and Storage, Technical University of Denmark 3 Fundamental Electrochemistry, Department of Energy Conversion and Storage, Technical University of Denmark
Reduction of H2O and oxidation of H2 was studied in a Ni-YSZ electrode supported Solid Oxide Cells produced at DTU Energy conversion (former Risø DTU). Polarisation (i-V) and electrochemical impedance spectroscopic characterisation show that the kinetics for reduction of H 2O is slower compared to oxidation of H2. The kinetic differences cannot be explained by the reaction mechanisms which are similar in the two cases but are rather an effect of the thermodynamics. The preliminary analysis performed in this study show that the slow kinetic for reduction is partly related to the endothermic nature of the reaction, cooling the active electrode, thereby leading to slower kinetics at low current densities. Likewise, the increased kinetic for oxidation was found to be related to the exothermic nature of the reaction, heating the active electrode, and thereby leading to faster kinetics. At higher current densities an increase caused by diffusion becomes more pronounced. © The Electrochemical Society.
E C S Transactions, 2012, Vol 50, Issue 49, p. 167-182
Energy conversion; Nickel; Oxidation; Reaction kinetics; Thermodynamics; Kinetics
Main Research Area:
Pacific Rim Meeting on Electrochemical and Solid-State Science, 2012