Influence of cationic doping at different sites in NaNbO3 on the photocatalytic degradation of methylene blue dye

Abstract

The present study presents the preparation of Nb-based perovskite with different cationic dopants (potassium and vanadium) for the catalytic photodegradation of methylene blue (MB) dye. For the preparation of powder samples, chemical route followed by heat treatment (at 800 °C) was adopted and X-ray diffraction confirmed the phase formation. Furthermore, scanning electron microscopy (SEM/EDX) and X-ray photoelectron spectroscopy supported the successful incorporation of dopants in NaNbO3 lattice. Furthermore, the induced lattice distortion and resulted optical modification were determined by uniform strain model and UV–visible spectroscopy, respectively. As a result of inclusion of dopants, photodegradation of MB dye under household CFL exposure has been studied in detail by considering the different dye concentrations (1, 5, and 10 mg/L). Doping at both sites (A and B) in NaNbO3 exhibited better photocatalytic efficiency (34%) in 5 h of illumination as compared to single cation-doped systems which can be associated to the higher content of lattice defects (as charge trap centers), reduced optical band gap and oxygen vacancies. Furthermore, intraparticle diffusion model suggested that low concentration of dye solution exhibited surface diffusion mechanism, while higher concentration followed boundary layer diffusion mechanism for the photodegradation of MB dye.