Visible-light-driven perovskite carbonaceous photocatalyst using LaNiO3/rGO composite for environmental remediation

Abstract

In this study, the facile hydrothermal method was used to fabricate pristine LaNiO₃ and LaNiO₃/rGO composites. Three composites were prepared by altering small amount of rGO content in the composites. Various characterization techniques were utilized to investigate the physical properties of as-fabricated samples including Powder X-ray diffraction, Scanning electron microscopy, Energy-dispersive X-ray, Raman and Photoluminescence. Band gap energies calculated from UV–visible spectra using Tauc plots of LaNiO₃, and LaNiO₃/rGO were 2.4 eV, and 2.2 eV respectively. Photoluminescence spectrum of LaNiO₃/rGO composite showed the lower peak intensity than pristine LaNiO₃ and rGO, which indicates the enhanced charge separation in charge carriers. The photocatalytic performance of LaNiO₃/rGO composite was evaluated by bisphenol A degradation and Cr(VI) reduction under visible light irradiation. Among all of the synthesized photocatalysts, it was proved that 15 % LaNiO₃/rGO composite was an outstanding photocatalyst for BPA degradation and Cr(VI) reduction than the other reported photocatalysts. The photooxidation activity and stability of LaNiO₃ was enhanced when rGO was incorporated in LaNiO₃. Complete degradation of 20 ppm solution of bisphenol A and reduction of Cr(VI) solutions were achieved in 25 min and 30 min, respectively by using 40 mg of 15 % LaNiO₃/rGO photocatalyst. BPA degradation and Cr(VI) reduction followed the pseudo first-order kinetics. The LaNiO₃/rGO composite exhibited outstanding stability for up to five cycles.