Synthesis and characteristics of ZnGa2O4 hollow nanostructures via carbon@Ga(OH)CO3@Zn(OH)2 by a hydrothermal method

ZnGa2O4 hollow nanostructures were synthesized by a two step hydrothermal and calcination process using carbon spheres as a template. We observed that the carbon@Ga(OH)CO3 core-shell nanostructures were covered by a uniform shell of Zn(OH)(2) nanoparticles when prepared using 2.5 mmol of ZnAc, and ZnGa2O4 hollow nanostructures with diameters of approximately 200 nm and shell thicknesses of around 15 nm could then be obtained. After calcination at 900 degrees C for 1 h, the amorphous core-shell-shell nanostructures yielded highly crystalline ZnGa2O4 hollow nanostructures. The shell possesses a single-crystal structure and a lattice spacing of around 0.253 nm which corresponds to the d spacing of (311) crystal planes of cubic ZnGa2O4. The composition and surface electron state of the ZnGa2O4 hollow nanostructures prepared at 900 degrees C were confirmed by X-ray photoelectron spectroscopy. UV and blue emissions of the ZnGa2O4 hollow nanostructures were found to result from self-activation centers of the octahedral Ga-O groups in the spinel structures and symmetry distortion of the octahedral sites by oxygen vacancies, respectively.