Theoretical Studies of Ion Transport and Surface Reactions In Solar Thermal Water Splitting by Mixed Metal Ferrites

We have used quantum simulations based on density functional theory within the periodic boundary condition approach to study the 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 reduction surface reactions that form O₂, and the transport of ions from the reduced/oxidized metal oxide interface to the surface in the STWS cycle. We investigate 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 the surface reactions to those of ion transport to determine the STWS bottleneck.