In order to determine the amount of hydrogen produced and
the stability of the materials with time, 25 redox cycles were performed
in a fully automated and programmable gas supply
microreactor (CATLAB, Hiden Analytical, UK) at 1 atm and 850 C.
After the fresh sample (50 mg) was placed inside, the microreactor
was flushed with a helium flow of 50 ml/min prior to commencing
testing. Each sample was subjected to multi-cycle
isothermal reduction under 5% carbon monoxide in helium and
isothermal oxidation under 5% water in helium with inlet flow
rates of 50 ml/min. Reduction and oxidation steps were performed
for 30 min. Helium was flushed for 15 min after reduction and oxidation
in order to evacuate the reactor of any reactive gas or any
product and to avoid mixing of the reducing and oxidising gases.