High Surface Reactivity and Water Adsorption on NiFe2O4 (111) Surfaces

Abstract

Transition metal-doped ferrites are attractive candidates for a wide range of applications including catalysis and electronic and magnetic devices. Although their bulk characteristics are well-understood, very little is known about their surface properties at the molecular level. Here, we demonstrate high reactivity of NiFe2O4 (111) surfaces, a Ni-doped ferrite, by elucidating the surface structure and water adsorption mechanism using density functional theory with on-site correction for Couloumb interaction (DFT + U). The surface reactivity of NiFe2O4 (111) surfaces (with 0.25 ML Fetet1 and 0.5 ML Feoct2–tet1 terminations) is shown to be significantly higher in comparison with the undoped Fe3O4 (111) surfaces. Dissociation of water is found to be highly favorable with an adsorption energy of −1.11 eV on the 0.25 ML Fetet1 terminated surface and −2.30 eV on the 0.5 ML Feoct2–tet1 terminated surface. In addition, we computed a low activation barrier of 0.18 eV for single water molecule dissociation on the ...