Role of carriers in the production of hydrogen from water by reduction-oxidation cycle of In 2O 3

Abstract

The promoting effects of various carriers on the decomposition of water by reduction-oxidation cycle of In 2O 3 have been examined. The most favorable carriers were ZrO 2, TiO 2, and MgO. Reduction and oxidation of indium oxide can be explained by “homogeneous model” which assumes rapid diffusion of oxygen ions from the surface of indium oxide grains into the bulk or vice versa, resulting in a homogeneous distribution of oxygen ions and indium metal. The promoting effect of carriers on reduction of In 2O 3 can be ascribed to the dispersion and stabilization of In 2O 3 grains on their surfaces. The effect of carriers on oxidation of the reduced indium oxide accompanying decomposition of water was explained by the activation of water molecules adsorbed at the boundary of indium oxide and carriers. The water molecules may be strongly polarized by the strong electrostatic field generated at the boundary.