(Invited) Thermochemical Properties of Non-Stoichiometric Oxides for Solar Fuel Generation

Abstract

Solar-driven thermochemical production of chemical fuels using redox active oxides has emerged as an attractive means for storing solar energy for subsequent use on demand. In this process a reactive oxide is cyclically exposed at high temperatures to an inert gas, which induces partial reduction of the oxide, and to an oxidizing gas of either H2O or CO2, which oxidizes the oxide, releasing H2 or CO. The capacity for fuel production is dictated by the thermodynamic properties of the oxide, specifically the enthalpy and entropy of reduction. Less appreciated is the fact that the fuel production rate is also highly dependent on the thermodynamic properties. Here we review progress made in measuring the thermodynamic functions for a range of materials and in identifying suitable thermodynamic values for efficient fuel production.