Screening of The Most Favorable Metal Oxides Systems for H2 Production via Solar Thermochemical Water Splitting

Abstract

Recently, green hydrogen production via solar thermochemical water splitting (STWS) as a clean and sustainable method is becoming a subject of interest to many researchers. Up to now, great effort is being made to develop a new material for STWS with low cost, provides good cycling stability and operates under mild conditions. In this paper, a thermodynamic study of different types of metal oxides including pure metal oxide, pure spinel metal oxides, and ferrite mixed oxides) was recoded to screen the most promising pairs for hydrogen production via STWS method.The obtained results showed the lowest reduction temperature (TR = 390 °C) related to the redox couple SrO2/SrO. However, the oxidation remains not thermodynamically feasible with water or using a strong oxidant such as NaOH. Besides, the couple Sb2O5/Sb2O3 shows good results in terms of reduction and oxidation temperatures (830 °C and 510 °C respectively). In addition, for spinel materials such Co3O4 and Mn3O4 the oxidation is only possible when NaOH is used. Finally, for ferrite systems and especially for NiFe2O4, a reduction temperature of 835 °C has been reported while more efforts should be directed to enhance the oxidation reaction feasibility of ferrite spinel systems.