Combined Density Functional Theory and Reduction Kinetics Investigation of Enhanced Adsorption of Hydrogen onto Fe2O3 by Surface Modification with Nickel

Abstract

Based on the density functional theory, the geometric structure, adsorption energy and density of states of H2/α-Fe2O3 (001) system and (H2 + Ni)/α-Fe2O3 (001) system were determined. The results showed that the absolute value of adsorption energy between H2 molecule and α-Fe2O3 (001) surface and the bond length of H2 molecule were increased by the presence of Ni atom. The presence of Ni atom promotes the adsorption of H2 molecule on α-Fe2O3 (001) surface. Reduction behavior of iron and nickel oxides in H2 atmosphere was determined by thermogravimetric analysis. The samples included Fe2O3, Fe2O3-NiO and Fe2O3-Ni systems. The effect of Ni and NiO on the reduction behavior of Fe2O3 was investigated. The ease of reduction within the following three systems decreases sequentially: Fe2O3-Ni > Fe2O3-NiO > Fe2O3. The activation energy of Fe2O3-Ni, Fe2O3-NiO and Fe2O3 systems at two temperature stages (viz. < 400 °C and > 400 °C) were 172 kJ·mol−1, 197 kJ·mol−1 and 263 kJ·mol−1 respectively.