Silver-ceramic nanocomposite catalysts for fuel cell cathodes by prof. Joon Hyung Shim published in advanced energy materials
A research team at Korea University developed an alternative to the platinum cathode, paving the way for the commercialization of fuel cells.
Prof. Joon Hyung Shim of the School of Mechanical Engineering at Korea University announced that his team was successful in developing silver-ceramic nanocomposite catalysts, which outperform platinum as fuel cell cathodes.
The study, with Hyung Jong Choi and Manjin Kim as co-first authors, was published in the eminent journal Advanced Energy Materials (Title: High-performance silver cathode surface treated with Scandia-stabilized zirconia nanoparticles for intermediate temperature solid oxide fuel cells). It was supported by the International Research & Development Program of the National Research Foundation of Korea and the Brain Korea 21 Plus Program. A research team led by Prof. Gyu-Tae Kim of the School of Electrical Engineering also participated in the study.
Fuel cells are highly efficient and environmentally friendly devices that generate electricity through electrochemical reactions between fuel and oxygen. As the core system of hydrogen cars and smart grids, they are expected to play a major role in creating a new energy paradigm. However, it has been difficult to commercialize fuel cells used at intermediate and low temperatures, for they require the use of expensive platinum catalysts.
Silver catalysts have long been regarded as an alternative to platinum as similar performance can be attained at a cost 100 times cheaper (platinum costs $628/cc, silver costs $5/cc). Silver particles, however, lack long-term stability as they tend to coagulate even under slight heat due to the delamination of the oxide layer.
The team prepared silver-scandia-stabilized zirconia (Ag-ScSZ) by depositing metallic scandia-zirconia nanoparticles through sputtering followed by thermal oxidization. As a result of the ScSZ ceramic particles coated on cathodes exhibiting high stability and ionic conductivity, they maximize the area of catalytic reactions and help to prevent the coagulation of silver.
When tested as ceramic fuel cell cathodes, the Ag-ScSZ composites surpassed cells with platinum cathodes by about 20% at 300-450 °C. They were superior to pure silver or platinum in terms of long-term stability.
Prof. Shim said, “The proposed Ag-ScSZ nanocatalysts are revolutionary materials that address the high cost of platinum and the poor stability of silver catalysts. We expect them to have a positive impact on the commercialization of fuel cells.”