Theoretical Studies of Ion Transport In Solar Thermal Water Splitting by Mixed Metal Ferrites In Traditional and Hercynite Cycles

We have used quantum simulations based on density functional theory within the periodic boundary condition approach to study ion transport occurring during solar thermal water splitting (STWS) by mixed metal ferrites. STWS occurs by cycling metal oxides through a high temperature reduction step and a lower temperature oxidation step where H₂O oxidizes the oxide and produces hydrogen gas. We investigate the transport of ions from the reduced/oxidized metal oxide interface to the surface in the traditional as well as hercynite STWS cycles and the effects of doping on the ion transport activation barrier. We have found that, in addition to lowering the reduction temperature, dopant ions has the added benefit of accelerating ion movement through the reduced phase. We compare the kinetics of ion transport to determine the differences in the traditional and hercynite cycles. The effects of magnetization were also studied to provide insight into similar processes taking place below the Currie temperature.