Electronic band gaps of ternary corundum solid solutions from Fe2O3–Cr2O3–Al2O3 system for photocatalytic applications: A theoretical study

Hematite is one of the promising candidates for the photocatalytic hydrogen production even though its poor charge transport properties still remain as a handicap. We have reported an all-electron DFT based calculation using the B3LYP hybrid functional on the electronic properties of a series of solid solutions from corundum type Fe2O3, Cr2O3 and Al2O3 systems. We calculated the electronic band gaps and structural parameters for 12 different compositions and the end members. The electronic band structure and the density of states of selected compositions are plotted and discussed. The calculations suggest corundum symmetry for the entire composition range. The results imply that there is a decrease in the electronic band gap for the ternary composition and a possibility of strain induced photoresponse. Band structure analysis suggests improved dispersion at the valence and conduction band edges which might improve the charge transport properties of the ternary system compared to the pure hematite. An observed shift in the valence and conduction band edges might bring improvements in the visible light harvesting of the material.