Chemical state analysis, optical band gap, and photocatalytic decolorization of cobalt-doped ZnO nanospherical thin films by DC/RF sputtering technique

Abstract

We have used direct current radio frequency (DC/RF) sputtering to deposit cobalt- incorporated zinc oxide (Co:ZnO) thin films on glass substrate. The x-ray diffraction (XRD) was applied for structural observation while topography was examined by atomic force microscopy (AFM). The optical studies were carried out by UV–vis absorption spectroscopy. The elemental composition was performed via x-ray photoelectron spectroscopy (XPS). The chemical state studies were also investigated. The shifting of XRD pattern towards higher diffraction angle confirmed successful incorporation. The optical observation showed “d–d” electron transition during the thin film deposition. The photocatalytic response was carried through the degradation of methylene blue (MB). The improved photocatalytic behavior of Co:ZnO thin films were attributed to the high binding energy component (HBEC) of oxygen vacancies. We have also proposed the tentative mechanism of cobalt incorporation into ZnO through XPS finding. We also checked the stability of deposited thin films. Co:ZnO thin films are new attractive candidates for degradation of waste dyes.