The photocatalytic properties of hollow (GaN)_1-x(ZnO)_x composite nanofibers synthesized by electrospinning

Highlights: • (GaN)_1-x(ZnO)_x composite nanofibers were obtained by electrospinning method. • Phase transition from ZnGa₂O₄ to (GaN)_1-x(ZnO)_x under NH₃ was observed. • Hollow and porous structure was confirmed by SEM and TEM investigation. • GaN:ZnO with optimal ratio of 1:2 displayed highest photocatalytic activity. - Abstract: (GaN)_1-x(ZnO)_x composite nanofibers with hollow structure were prepared by initial electrospinning, and the subsequent calcination and nitridation. The structure and morphology characteristics of samples were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The characterization results showed the phase transition from ZnGa₂O₄ to (GaN)_1-x(ZnO)_x solid-solution under ammonia atmosphere. The preparation conditions were explored and the optimum nitridation temperature and holding time are 750 °C and 2 h, respectively. The photocatalytic properties of (GaN)_1-x(ZnO)_x with different Ga:Zn atomic ratios were investigated by degrading Rhodamine B under the visible light irradiation. The photocatalytic activity sequence is (GaN)_1−x(ZnO)_x (Ga:Zn = 1:2) > (GaN)_1−x(ZnO)_x (Ga:Zn = 1:3) > ZnO nanofibers > (GaN)_1−x(ZnO)_x (Ga:Zn = 1:4) > (GaN)_1−x(ZnO)_x (Ga:Zn = 1:1). The photocatalytic mechanism of the (GaN)_1−x(ZnO)_x hollow nanofibers was further studied by UV–vis diffuse reflectance spectra. The excellent photocatalytic performance of (GaN)_1−x(ZnO)_x hollow nanofibers was attributed to the narrow band gap and high surface area of porous nanofibers with hollow structure.