(186b) Investigating Lanthanides and Transition Metal Pair Charged Compensating Doped CeO2 Materials

Thermochemical gas splitting has been identified as a promising method of harnessing solar energy to produce solar fuels. In this process, a metal oxide first undergoes an endothermic reduction using concentrated solar energy, followed by an exothermic oxidation utilizing CO₂ or H₂O, re-oxidizing the metal oxide and forming CO or H₂ respectively. CeO₂ has emerged as the state-of-the-art material due to high stability and redox kinetics. However, ceria requires extremely high reduction temperatures, ~1500 °C and low oxygen partial pressures, 10^-6 atm to access these favorable oxygen exchange capabilities. Previous work has identified a paired charged compensating doped (PCCD) ceria strategy as a means of lowering the O-vacancy formation energy. In this strategy, ceria is co-doped with trivalent and pentavalent cations to mimic the effects of successful tetravalent doping, but with a larger, trivalent-dopant dependent, O-vacancy formation energy range. Here, we report on the thermodynamics of additional PCCD materials outside of the IIIA and VA groups previously studied. Fe/Ni/Co/Pr and Nb co-doped ceria is investigated using thermogravimetric analysis and van’t Hoff to elucidate the thermodynamic trends of lanthanides and transition metal substituted PCCD materials compared to native ceria.