Solubility and crystallographic facet tailoring of (GaN)1−x(ZnO)x pseudobinary solid-solution nanostructures as promising photocatalysts

Abstract

(GaN)_1−x(ZnO)_x solid-solution nanostructures with superior crystallinity, large surface areas and visible light absorption have been regarded as promising photocatalysts for overall water splitting to produce H₂. In this work, we report the preparation of (GaN)_1−x(ZnO)_x solid-solution nanorods with a high ZnO solubility up to 95% via a two-step synthetic route, which starts from a sol–gel reaction and follows with a nitridation process. Moreover, we clearly demonstrated that the crystallographic facets of (GaN)_1−x(ZnO)_x solid-solution nanorods can be finely tailored from non-polar {100} to semipolar {101} and then finally to mixed {101} and polar {000} by carefully controlling the growth temperature and nitridation time. Correspondingly, the ZnO content in the GaN lattice can be achieved in the range of ∼25%–95%. Room-temperature cathodoluminescence (CL) measurements on the three types of (GaN)_1−x(ZnO)_x solid-solution nanorods indicate that the minimum band-gap of 2.46 eV of the solid-solution nanorods is achieved under a ZnO solubility of 25%. The efficiency and versatility of our strategy in the band-gap and facet engineering of (GaN)_1−x(ZnO)_x solid-solution nanorods will enhance their promising photocatalytic utilizations like an overall water splitting for H₂ production under visible-light irradiation.