Modeling Zn3O3/Ga3O3 composite for water splitting: a first-principle DFT study of electronic structure and interfacial reactivity

Abstract This study employs Density Functional Theory (DFT) at the B3LYP/LANL2DZ level to investigate the structural and electronic properties of a Zn 3 O 3 /Ga 3 O 3 composite and its interaction with water clusters. Using the Gaussian 09 suite, the research analyzes model molecules of Zn 3 O 3 , Ga 3 O 3 , and their composite to evaluate kinetic stability and chemical reactivity through HOMO-LUMO energy gaps and Total Dipole Moments (TDM). The results demonstrate that the Zn 3 O 3 /Ga 3 O 3 composite is a tunable nanostructure whose electronic properties are highly sensitive to its interface and the presence of external moisture. The study used Molecular Electrostatic Potential (MESP) and Non-Covalent Interaction (NCI) methods to show that water adsorption becomes more stable through the combined effect of strong metal-oxygen coordination and hydrogen bonding and weak van der Waals forces. The Density of States (DOS) analysis demonstrated that the electronic structure and interfacial stability both changed because of the observed modulation. These findings provide critical insights into the initial steps of photocatalytic water splitting and suggest the composite as a promising candidate for water capture and catalytic applications. These results indicate that interfacial electronic coupling between Zn and Ga oxide domains enhances water affinity and electronic responsiveness, representing a key step in photocatalytic water splitting mechanisms. The findings provide atomistic insight into how heterostructured oxide composites can be rationally engineered to improve water capture, charge separation, and catalytic efficiency, highlighting the Zn₃O₃/Ga₃O₃ composite as a promising model for next-generation photocatalytic water splitting by optimizing surface adsorption and interfacial electronic coupling.