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 H 2 /α-Fe 2 O 3 (001) system and (H 2 + Ni)/α-Fe 2 O 3 (001) system were determined. The results showed that the absolute value of adsorption energy between H 2 molecule and α-Fe 2 O 3 (001) surface and the bond length of H 2 molecule were increased by the presence of Ni atom. The presence of Ni atom promotes the adsorption of H 2 molecule on α-Fe 2 O 3 (001) surface. Reduction behavior of iron and nickel oxides in H 2 atmosphere was determined by thermogravimetric analysis. The samples included Fe 2 O 3 , Fe 2 O 3 -NiO and Fe 2 O 3 -Ni systems. The effect of Ni and NiO on the reduction behavior of Fe 2 O 3 was investigated. The ease of reduction within the following three systems decreases sequentially: Fe 2 O 3 -Ni > Fe 2 O 3 -NiO > Fe 2 O 3 . The activation energy of Fe 2 O 3 -Ni, Fe 2 O 3 -NiO and Fe 2 O 3 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.