A review of wet impregnation—An alternative method for the fabrication of high performance and nano-structured electrodes of solid oxide fuel cells

Development of solid oxide fuel cells (SOFC) for operation at intermediate temperatures of 600–800 °C with hydrocarbon fuels requires a cathode and anode with high electrocatalytic activity for O2 reduction and direct oxidation of hydrocarbon fuels, respectively. Wet impregnation is a well known method in the development of heterogeneous catalysts. Surprisingly, very few have concentrated on the application of the wet impregnation technique to deposit nano-sized particles into the established electrode structure of the SOFC. This paper reviews and discusses the progress in the application of the wet impregnation technique in the development of Ni-free Cu-based composite anodes, doped CeO2-impregnated (La, Sr)MnO3 (LSM) cathodes and Ni anodes, Co3O4-infiltrated cathodes and precious metal-impregnated electrodes. Enhancement in the electrode microstructure and cell performance is substantial, showing the great potential of the wet impregnation method in the development of high performance and nano-structured electrodes with specific functions. However, the long-term stability of the impregnated electrode structure needs to be addressed.