November 6, 2013
Kayla Weston took 1st place in the Materials Engineering and Sciences Division Undergraduate Student Poster Competition at the AIChE 2013 Annual Meeting in San Francisco for her poster titled ”A Method for Clean H2 Generation from Solar Heat and Water.”
Weston is a member of the Weimer group.
Solar thermal water splitting is a method to transform diffuse, temporal, solar energy into a useful chemical fuel, namely H2 that can be stored, transported and efficiently used. Solar thermal water splitting occurs when a metal oxide, “hercynite” material in this study, is heated using solar thermal energy to above 1200 oC where by it reduces generating oxygen. Traditionally, the material is then cooled ~ 300-500 oC below the thermal reduction temperature and exposed to steam whereby the steam re-oxidizes the metal oxide and produces H2 gas. The metal oxide is subsequently cycled between the oxidation and reduction steps resulting in an overall reaction of H2O + solar thermal energy → H2 + ½O2. The “hercynite” material used experimentally was synthesized using atomic layer deposition (ALD). ALD is a thin film coating technique that allows for a layer-by-layer deposition of metal oxides at the desired ratios and thickness. Thin films with high porosity are desired as they allow for decreased diffusional and thermal resistances. We demonstrate water splitting cycles using “hercynite” active material where the oxidation and reduction steps are carried out under isothermal conditions and that this is beneficial from an efficiency, total hydrogen generation, and material thermal stress standpoint. Additionally, in collaboration with Sandia National Laboratories, a follow up investigation of isothermal solar thermochemical cycling was carried out in order to better understand the cycle capacity and hydrogen productivity of hercynite materials over a range of operating temperatures and reactive gas partial pressures.