Development of Materials for Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices that operate at high temperature to convert the chemical potential energy of a fuel (such as Hydrogen) and an oxidant (oxygen, usually from air) directly into electrical energy at high efficiencies and with low environmental impact. SOFCs generate high grade heat during operation as well as electrical energy. If this can be utilised in Combined Heat and Power (CHP) systems, efficiencies of over 80% are achievable. SOFCs have similar structures to batteries. The fuel is oxidised electrochemically at the anode by reaction with oxygen ions generated from reduction of molecular oxygen at the cathode and transported to the anode through the electrolyte. There is much interest in developing SOFCs to run directly on hydrocarbon fuels, rather than Hydrogen, in order to avoid the additional steam reforming step. Conventional SOFC anode materials are not suitable for use with hydrocarbons because they become rapidly deactivated. New catalyst compositions are therefore required. After introducing the concept of SOFCs I will present some recent results on the development of anode catalyst materials for the direct use of hydrocarbons in SOFCs. The preparation and catalytic and electrochemical evaluation of one such set of materials, nanoparticulate mixed oxides of formula CexZr1-xO2-d (x=0.1 – 0.9), will be covered in detail. Recent work on SOFC electrolytes will also be addressed if time permits.