Fundamentals of solar thermochemical gas splitting materials

Solar thermochemical processes are inherently chemical reactions between various gas phases and an oxygen carrier in order to split the endothermic gas splitting reaction into several reactions which are more thermodynamically favorable. Thus, the effectiveness of the overall processes necessarily depends on the effectiveness of the individual steps. In this Chapter, we discuss the reactive materials which facilitate solar thermochemical water and carbon dioxide splitting. We provide an overview of the process, cover the thermodynamic constraints on the materials and individual steps, provide overview of the main categories of active materials. Lastly, we briefly discuss methods of measuring and calculating the thermodynamics of materials, which are crucial techniques for new materials discovery and system modeling.