Study of the performance of Co and Ni ferrites after several cycles involved in water-splitting thermochemical cycles

Water splitting thermochemical cycles based on metal oxide systems and using concentrated solar energy is a promising and sustainable clean process for hydrogen production. In this work, the capability of Ni and Co powder ferrites for hydrogen production via two step redox processes has been tested. In order to avoid decreasing of the hydrogen release with the number of cycles due to powder sintering, a simple handmade pellet preparation has been used. Then, samples in the forms of pellets or powders were tested for the water splitting reaction under the same experimental conditions, and the amount of hydrogen generated in each case has been compared. Results show that pellet samples maintain their shape after the cycling process, although higher hydrogen production rate is obtained for Ni ferrite powder samples. This study also includes a thorough chemical, structural and morphological characterization of the samples after thermochemical cycling.