Preparation and surface characterization of nanodisk/nanoflower-structured gallium-doped zinc oxide as a catalyst for sensor applications

Abstract

Nanostructured gallium-doped zinc oxide (GZO) thin films were fabricated on piezoelectric substrates. The GZO thin films with nanodisk/nanoflower morphologies were prepared by a simple spin-coating process followed by one-step hydrothermal treatment. Addition of polymer during hydrothermal treatment resulted in nanodisk and nanoflower morphologies. The morphology, microstructure and chemical composition of thin films prepared under different conditions were examined by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Raman spectroscopy. The XRD and FE-SEM investigations confirmed that the GZO nanodisks, nanorods and nanoflowers formed on the AlN/Si substrates were all wurtzite phase. Green fluorescent protein (GFP) was immobilized on the as-synthesized GZO nanostructured materials by a dipping process. Atomic force microscopy (AFM) and fluorescence spectroscopy measurements were conducted to confirm the surface binding nature of GFP on the GZO nanostructures to determine their suitability for use in sensor applications and bioimaging techniques. Trace-level addition of GFP to the GZO nanostructures resulted in a fluorescence response, revealing good activity for ultraviolet light sensor applications.