(780a) Assessing the Thermodynamic Viability of Mixed Metal Oxides for Solar Thermochemical Water Splitting

While solar energy is the most abundant renewable energy resource, the capture, storage, and distribution of it remains a challenge. Solar thermochemical water splitting (STWS) provides a promising route for efficient utilization of this disperse resource since it allows for use of the entire solar spectrum to convert water to an energy dense fuel, H₂. However, despite a significant number of materials having been examined, an optimal redox material to drive this process has yet to be developed. In order to be viable for economic hydrogen production, materials must for have high hydrogen productivity, fast reduction and oxidation kinetics, low thermal reduction temperatures, and long term stability and reactivity. In this work we will utilize ab initio methods to assess the thermodynamic viability of a large number of spinel and perovskite metal oxides for STWS. Materials will be screened for stability, oxygen vacancy formation energy, and extent of reduction. The effect of temperature on the parameters including crystal structure, cation disorder, and magnetic order and their relationship to predicted STWS ability will be discussed. Compositional (doping) control will be utilized to optimize materials’ thermodynamic properties. Experimental results from redox cycling in a stagnation flow reactor will be presented and compared to DFT models.