Effects of VZn and Hi interstitials with different valence states and alkaline earth metal doping on carrier lifetime, activity, and oxidation–reduction reaction of ZnO

Abstract

We applied the generalized gradient approximation plane wave ultrasoft pseudopotential method based on the framework of density functional theory in this work to study the influences of Be/Mg/Ca single doping and the coexistence of Zn vacancies with different valence states and H interstitial on the magnetic and photocatalytic properties of ZnO. Results showed that the formation energy of all doping systems decreases with the increase in the valence state of Zn vacancies, and the doping is easy. The binding energies of all doped systems under O-rich conditions are lower than those under Zn-rich conditions, and the doped systems are more stable under O-rich conditions. The Zn34MO36 (VZn1−, M = Be/Mg/Ca), Zn34MHiO36 (VZn1−, M = Be/Mg/Ca), and Zn34MHiO36 (VZn0, M = Mg/Ca) systems show magnetism. The source of the magnetism of the doped system is generated by the itinerant electrons of unpaired spin polarization of the O atom near VZn. The study found that the Zn34MgHiO36(VZn2−) system has the longest carrier lifetime, relatively large electric dipole moment, significant red shift of the absorption spectrum, and strong redox ability. The Zn34MgHiO36 (VZn2−) system can be used as a photocatalyst for H2 production. The result of this work has theoretical reference value for the design and preparation of new magneto-optical functional materials.