Transition metal doped ceria for solar thermochemical fuel production

In this paper, the effect of doping of transition metal cations on thermal reduction and CO2 splitting ability of Ce0.9M0.1O2-delta materials (where, M = Ni, Zn, Mn, Fe, Cu, Cr, Co, Zr) is investigated by performing multiple thermochemical cycles using a thermogravimetric analyzer. The Ce0.9M0.1O2-delta materials are successfully derived via co-precipitation method and analyzed via powder X-ray diffraction (PXRD), scanning electron microscope (SEM), and BET surface area analyzer (BET). The Ce0.9M0.1O2-delta materials derived are further tested towards their O-2 releasing and CO production capacity by performing ten thermochemical CO2 splitting cycles. The obtained TGA results indicate that CeZn and CeFe are capable of releasing higher amounts of O-2 as compared to other Ce0.9M0.1O2-delta materials at 1400 degrees C. Likewise, these two oxides are again observed to be better than other Ce0.9M0.1O2-delta materials in terms of their CO production capacity at 1000 degrees C. For instance, CeZn and CeFe releases an average of 50.5 and 50.0 mu mol of O-2/g.cycle during ten thermochemical cycles in which the thermal reduction step is performed at at 1400 degrees C. Also, the CO production capacity of CeZn and CeFe material is observed to be equal to 103.3 and 96.3 mu mol of CO/g.cycle for ten thermochemical cycles in which the CO2 splitting is carried out at 1000 degrees C. The compositional and thermal stability of all Ce0.9M0.1O2-delta materials is also analyzed after performing ten thermochemical cycles. The phase composition of all the Ce0.9M0.1O2-delta materials remain unchanged after performing ten thermochemical cycles. However, the crystallite size of all the Ce0.9M0.1O2-delta materials increases after performing the ten thermochemical cycles due to the high temperature processing.