Research is directed at the interface of surface functionalization using ALD and solar-thermal processing to develop thin film materials that provide for rapid solar thermal cycling to split water and/or carbon dioxide. The focus of the work is development of ferrite spinel materials that can be thermally reduced at high temperatures to release oxygen and then are subsequently exposed to water, producing high purity hydrogen and recovering the original ferrite spinel form in the process. The use of thin films reduces diffusional limitations and provides for an opportunity to cycle the active materials quickly in order to produce renewable hydrogen in an economic fashion. Projects in this area are focused on producing high surface area substrates to be used for the deposition, demonstration of the materials and identification of the kinetics using stagnation flow reactors and a thermogravimetric analyzer. Efforts are also underway to evaluate the robustness of the active materials and their application in devices for demonstration on-sun at the NREL. Major developments in the lab include the discovery and demonstration of materials to carry out thermal reduction at about 250oC below conventional ferrites, at temperature far below liquid phase sintering where rapid and permanent deactivation would occur.
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