Methods and materials for the thermochemical production of hydrogen from water

A method of thermochemically forming H2, O2, or both H2 and O2 from water, said method comprising:

• (a) contacting a composition comprising a spinel-type transition metal oxide of formula M3O4 with an alkali metal carbonate, bicarbonate, or mixture thereof in the presence of H2O at a first temperature in a range of from 450° C. to 1000° C. to form H2, CO2, and an alkali metal ion-transition metal oxide, said alkali metal ion-transition metal oxide having an average transition metal oxidation state that is higher than the average oxidation state of the transition metal in the spinel-type transition metal oxide;
• (b) hydrolytically extracting at least a portion of alkali metal ions from the alkali metal ion-transition metal oxide by the reaction with CO2 and liquid H2O at a second temperature in a range of from 60° C. to 250° C. to form a transition metal composition comprising an oxidized ion extracted-transition metal oxide in which the average oxidation state of the transition metal in the oxidized ion extracted-transition metal oxide is the same as the average oxidation state of the transition metal in the alkali metal ion -transition metal oxide;
• and
• (c) thermochemically reducing the transition metal composition of step (b) at a third temperature in a range of from 450° C. to 1150° C., with the associated formation of O2;
• wherein the transition metal, M, comprises iron, manganese, or a combination thereof, and the corresponding spinel-type transition metal oxide comprises Fe3O4, Mn3O4, or a solid solution or physical mixture thereof;
• and
• wherein the alkali metal ion comprises sodium ion, potassium ion, or a combination thereof.