Explorations of physicochemical, photodegradation, phototoxicity, and kinetics of Bi2-2xCoxCdxO3/rGO nanocomposites for wastewater treatment applications

Abstract

In recent times, there has been a pressing need to discover or manufacture a unique material that can serve as a photocatalyst for organic pollutants that are incapable of degradation. Pure Bi2O3 and Co, Cd co-doped Bi2-2xCoxCdxO3 (x = 0.8) nanoparticles were synthesized using the chemical co-precipitation method, but the new approach involves fabricating 10 % reduced graphene oxide Bi2-2xCoxCdxO3/rGO nanocomposites via the ultra-sonication route. This study investigated the effects of Co, Cd, and r-GO doping on the optical, electrochemical, structural, and photocatalytic properties of bismuth oxide. The synthesized nanomaterials were analyzed using X-ray diffraction (XRD), cyclic voltammetry, ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR), photoluminescence (PL), and Raman spectroscopy. The XRD patterns showed the formation of a monophasic monoclinic structure belonging to space group P21/c, with an average crystallite size estimated around 22–41 nm. According to the UV–visible study, the bandgap energy of Bi2O3 NPs, Bi2-2xCoxCdxO3 NPs, and Bi2-2xCoxCdxO3/rGO nanocomposites were 2.64 eV, 2.37 eV and 2.06eV respectively. The cyclic voltammetry technique was used to evaluate the functioning electrodes. In contrast to un-doped Bi2O3, the synergistic effects of Co, Cd, and r-GO on the substituted material increased the specific capacitance. The pure Bi2O3, doped Bi2-2xCoxCdxO3, and Bi2-2xCoxCdxO3/rGO photocatalyst degraded 62 %, 85 %, and 95.4 % respectively of RB-5 dye after 105 min of sunlight. The phytotoxicity analysis examined the germination of Hordeum vulgare seeds in treated and untreated RB-5 dyes. Additionally, scavenging investigations using reactive species trapping to confirm the dominant reactive species were evaluated. Bi2-2xCoxCdxO3/rGO nanocomposites are better at photocatalysis and have a narrow bandgap, which makes them useful as solar-active photocatalysts for getting rid of dyes in wastewater. In future, their composites with conducting polymers may improve their electrochemical and photocatalytic behaviour as well.