Fundamental Bulk/Surface Structure-Photoactivity Relationships of Supported (Rh2-yCryO3)/GaN Photocatalysts

The supported (Rh2-yCryO3)/GaN photocatalyst was examined as a model nitride photocatalyst system to assist in the development of fundamental structure photoactivity relationships for UV activated water splitting. Surface characterization of the outermost surface layers by high-sensitivity low energy ion scattering (HS-LEIS) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) revealed that the GaN support consists of a GaOx outermost surface layer on a thin film of GaOxNy. HR-XPS demonstrates that the supported (Rh2-yCryO3) mixed oxide nanoparticles (NPs) consist of Cr3+ and Rh3+ cations that are surface enriched for (Rh2-yCryO3)/ GaN. Raman and UV-vis spectroscopy show that the bulk molecular and electronic structures, respectively, of the GaN support are not perturbed by the deposition of the (Rh2-yCryO3) NPs. The function of the GaN bulk lattice is to generate photoexcited electrons/holes, with the electrons harnessed by the surface Rh3+ sites for evolution of H-2 and the holes trapped at the Ga oxide/oxynitride surface sites for splitting,of water and evolving O-2.