(197b) Thermochemical Water Splitting for Iron Oxide Deposited On Zirconia and Zirconia- Doped Yttria

Several iron oxide catalysts supported on various high temperature stable oxides were prepared and identified as promising for activity testing for the thermochemical splitting of water. This two-step reaction is an environmentally friendly method for producing hydrogen while safely separating out oxygen, if solar energy is used to provide the heat for the reaction. However, since very high temperatures are needed to thermally remove oxygen from the catalyst. Our research is focused on limiting the sintering of the catalysts and reducing the temperature required for reaction.

Nanoparticle zirconia (n-ZrO₂) support has shown promise in alleviating sintering. After heating to 1500°C, iron oxide on n-ZrO₂ catalyst remains loosely agglomerated albeit as larger particles instead of a dense hard disk as other oxide supports form. The n-ZrO₂ and zirconia-doped with yttria (ZrO₂-Y₂O₃) supported catalyst were cycled to determine activity where each cycle consists of alternating a thermal heating followed by passing water vapor over a reduced iron oxide phase.

Although catalyst characterizations show iron oxide particle growth on the support surface, x-ray diffraction (XRD) on the iron oxide on ZrO₂-Y₂O₃ catalyst indicates the active iron oxide enters the ZrO₂-Y₂O₃ lattice. The appearance of the active iron oxide phase within the oxide support’s lattice network demonstrates ability to limit sintering and in turn sustain activity over additional cycles.