In our work, we have prepared an array of gallium zinc oxynitrides (GaxZn1-xOyN1-y) as a model system using a combustion synthesis method and demonstrate that gallium zinc oxynitrides can be synthesized in 30 minutes at 500 oC using this method. X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) are used to characterize the physical properties of the as-synthesized materials. XPS analysis reveals that as much as 50% nitrogen substitution in the metal oxide lattice can be achieved, dependent on the ratio of gallium and zinc nitrates used as precursors. XPS also reveals that the nitrogen valency is that of a nitride material, as would be expected for a substitution into the crystal lattice. Relative atomic concentrations from XPS also reveals that the complex formed is essentially GaN:ZnO. UV-visible spectroscopy reveals that the band gap of the GaxZn1-xOyN1-ymaterials can be controlled simply by altering the precursor ratio. X-ray diffraction measurements reveal shifts in the crystalline peaks from ZnO toward GaN, confirming the incorporation of nitrogen into the lattice. The as-synthesized products are capable of generating photocurrent from visible light irradiation and are able to carry out water splitting in pure water without any co-catalysts, such as Pt, IrO2, or Rh/Cr2O3.
Finally, we discuss how to take the results gained from this work and expound upon it to begin the search for new candidate oxynitride materials, including potential high-throughput methods for rapid screening of such candidates. We also discuss the apparent conditions necessary for successful formation of an oxynitride material based on initial experiments with new candidates.