(200c) Measurement of Oxygen Release from Redox Samples for Solar Fuel Production

The characterization of reduction-oxidation chemistry is important for the ongoing development of thermochemical cycles for solar fuel production. Materials like cerium oxide and perovskites have been studied in depth for their fuel production potential and mechanical stability during temperature cycles in the range of 1000 to 1500 degrees C. Accurate characterization of these materials is dependent on measurement of the gaseous products. A particular challenge is the measurement of oxygen release from samples. In the current study, a thorough investigation is performed of several options for measuring oxygen release rates due to high temperature cycling of solid metal oxides. An infrared furnace capable of extreme heating rates is used to chemically cycle solid redox-active metal oxides. Oxygen sensors located in the high temperature reaction tube and after gas cooling are compared to measurements from a mass spectrometer. Experimental data are given for qualification of the system using known gas compositions and for actual chemical cycling experiments. The potential errors due to time delays and diffusion effects are quantified. The resulting implications for future measurement systems are described.