Effect of doping elements on redox kinetics of NiO-YSZ powders for SOFC applications

In the present work, the effect of different amounts of Al and Ce oxides on reduction and oxidation kinetics of NiO/YSZ powders was investigated by thermogravimetric analysis at 800°C in H2/Ar (reduction) or air (oxidation) atmosphere associated with detailed microstructural investigation of the samples. Both doping elements increase reduction and oxidation rates. The reduction rate increases monotonically with Al amount, while only when high Ce loads are used the first reduction rate is affected significantly. The second reduction and re-oxidation are faster than the first one. The presence of coarser NiO particles generated in the first cycle and a consequent porosity modification can explain the generalized reaction rate increase. ©The Electrochemical Society.