Pulsed laser-assisted synthesis of metal and nonmetal-codoped ZnO for efficient photocatalytic degradation of Rhodamine B under solar light irradiation

Abstract

Solar light-active silver nanoparticle (Ag NP) and nonmetal nitrogen (N)-codoped zinc oxide (ZnO:N/Ag) nanocomposites were fabricated by a pulsed laser-assisted method. N was considered as a promising candidate for tailoring the bandgap of ZnO due to the similar atomic radius as well as lower ionization energy and electronegativity compared to oxygen, which resulted in the formation of a shallow acceptor level in ZnO. Moreover, Ag NPs could enhance the optical properties of the ZnO materials as a consequence of the surface plasmon resonance (SPR) effect. The synthesized ZnO:N/Ag composite materials were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), UV–vis diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) analysis. The photocatalytic activity of the ZnO:N/Ag materials was evaluated for the efficient degradation of Rhodamine B (Rh.B) under solar light irradiation. The optimized ZnO:N/Ag-2 nanocomposite exhibited six times higher Rh·B degradation rate than pure ZnO. This was attributed to the enhanced absorption behavior in the solar region as well as the formation of the Schottky junction between ZnO:N and Ag NPs, which resulted in effective charge separation. In addition, the scavenger study revealed that •O2− radicals facilitated the degradation of Rh.B. The reusability test of the ZnO:N/Ag nanocomposite confirmed high photostability and efficiency of the material in each successive cycle. The present investigation illustrates a rational design of metal and nonmetal-codoped ZnO nanostructures employing a pulsed laser-assisted technique for effective application in photocatalytic remediation of wastewater.