produced from other sources of energy, so it is often referred as an energy carrier unlike a primary energy
source like coal. Hydrogen is an efficient way to store and transport a huge amount of energy since it has
a high calorific value than any fossil fuel. Solar thermo-chemical methods, one of the methods to produce
hydrogen are based on the cyclic process of reduction and oxidation of metal oxides and metals
respectively. The hydrogen and oxygen are by-products of the reaction. Several two-step water-splitting
cycles based on metal oxide redox reactions including ZnO/Zn, TiO2/TiOx, Mn3O4/MnO and Co3O4/CoO
have been proposed. But the cycle based on Zn/ZnO redox reactions [1] has much higher practical
hydrogen yield and operates at a moderate temperature compared to ferric and ceria cycles except
carbothermal reduction of ZnO.