Catalyst-free synthesis of a three-dimensional nanoworm-like gallium oxide–graphene nanosheet hybrid structure with enhanced optical properties

Abstract

We here report the synthesis and growth of catalyst-free three-dimensional β-gallium oxide nanoworm-like nanostructures on graphene nanosheets (3D β-Ga₂O₃@GNSs) using a solid mixture of graphite oxide and gallium acetylacetonate by the microwave (MW)-assisted method for the first time. The MW-assisted synthesis of the 3D β-Ga₂O₃@GNSs hybrids contains 1D semiconducting β-Ga₂O₃ nanoworms (NWs) and 2D highly conducting graphene nanosheets (GNSs) materials. The β-Ga₂O₃ NWs have an average diameter of 200 nm and lengths of up to ∼1 μm grown on the GNSs. These 3D β-Ga₂O₃@GNSs hybrids have been synthesized in a very short time with scalable amounts. The controlling parameters such as MW irradiation time and power were found to greatly influence the structural morphology of the as-synthesized 3D β-Ga₂O₃@GNSs hybrid. This method for the synthesis of 3D β-Ga₂O₃@GNSs hybrids is imperative due to it allowing excellent control over experimental parameters, being low cost and having better reproducibility. Also, the catalyst-free MW-assisted method is a much more rapid and thus higher throughput alternative for effective and scalable growth over the conventional heating method. The crystallinity, structure, morphology, and optical analysis of the 3D β-Ga₂O₃@GNSs hybrids are carried out utilizing several techniques. The formation of the 3D β-Ga₂O₃@GNSs hybrids shows a band gap variation from 4.94 to 4.48 eV associated with the structural evolution. A suitable growth mechanism has been suggested for the formation of these 3D β-Ga₂O₃@GNSs hybrids.