First-Principles Studies of the Structural and Electronic Properties of the (Ga1-xZnx)(N1-xOx) Solid Solution Photocatalyst

Design of visible-light-driven photocatalytic materials has attracted intense interest in recent years in an attempt to enhance photonic efficiencies of hydrogen production via water splitting. Recent studies have shown that a solid solution of GaN and ZnO, (Ga1-xZnx)(N1-xOx), can oxidize water under visible light in the presence of a sacrificial electron acceptor. Here we present a systematic study of the structural and electronic properties of this (Ga1-xZnx)(N1-xOx) solid solution as a function of zinc (oxygen) concentration, x, using density-functional theory (DFT). The DFT+U approach has been adopted, and two different periodic supercells, the 16-atom (Ga8-nZnn)(N8-nOn) and 32-atom (Ga16-nZnn)(N16-nOn), have been used to model this solid solution. Results obtained from both supercells are in qualitative agreement with available experimental findings (in the lower concentration range x < 0.25), although overall the larger 32-atom supercell provides a better description of the (Ga1-xZnx)(N1-xOx) solid ...