- CeO2-δ particles were produced by a modified Pechini method, where Ce(NO3)3 x 6 H2O was solubilized in water, and mixed with citric acid (Macron Fine Chemicals, ACS Grade) and ethylene glycol (Macron Fine Chemicals, ACS Grade) in a 1:2.6:11.2 molar ratio, as a precursor solution. Precursor solution was stirred over a hot plate at 120 °C for several hours until solution viscosity obviated use of the stir bar, at which point the stir bar was removed and the solution transferred to an alumina crucible and returned to the hot plate to dehydrate for minimum 12 hours. Dehydrated precursor solution was then calcined at 500 °C for 5 hours, ramp rate of 5 °C/min. Calcined particles were ground in mortar and pestle and sintered at 750 °C for 4 hours, ramp rate of 5 °C/min. Peak position of particle X-ray diffraction corresponds to the cubic fluorite structure of CeO2-δ (JCPDS 04-0593; Figure ).