Physicochemical, photocatalytic degradation, recyclability, kinetics, and scavenging studies of Bi2-2xCoxZnxO3 nanoparticles with reactive black 5 dye

Abstract

Semiconductor photocatalysis technology has great potential as a viable alternative to conventional scientific and technological approaches. The chemical co-precipitation approach was employed in this study to synthesize pure Bi₂O₃ and doped Bi_2-2xCo_xZn_xO₃ NPs (where x = 0.0, 0.2, 0.4, 0.6, and 0.8). The effects on the structural, morphological, optical, electrochemical, and photocatalytic features were evaluated. The samples were characterized by using XRD, SEM, TEM, XPS, BET, FTIR, PL, CV, Raman and UV–Vis, spectroscopy. The XRD spectra verified that the structure is monoclinic, with a space group of P2₁/c. Additionally, the average size of the crystallites was between 24 and 49 nm. Scanning Electron Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM) were used to evaluate the materials' surface morphology. The existence of functional groups in Bi_2-2xCo_xZn_xO₃ nanoparticles was confirmed by FTIR measurements. The photoluminescence (PL) spectra of the synthesized nanomaterials revealed a significant occurrence of charge separation (e⁻-h⁺) and a minimal rate of recombination in the extensively substituted materials which is responsible for the enhancement of photocatalytic activity. Cyclic voltammetry was employed to investigate the functional electrodes. Using a potential window ranging from 0 to 0.4 V, the cyclic voltammogram of each working electrode was seen at various scan rates (10-40 mVs^–1). In comparison to pure Bi₂O₃, the specific capacitance was improved by the synergistic effects of Co and Zn in the Bi_2-2xCo_xZn_xO₃. The purpose of the XPS investigation to analyze the chemical composition and surface valence state of Co and Zn doped Bi₂O₃ NPs. The optical band gap was evaluated using UV–Vis spectroscopy and showed a decreasing trend from 2.66 to 2.22 eV with increasing the doping concentration. BET analysis was used to determine the surface areas of pure Bi₂O₃ and doped Bi_2-2xCo_xZn_xO₃ NPs using nitrogen (N₂) at 78K and desorption/adsorption isotherms. The photocatalytic activity of Bi_2-2xCo_xZn_xO₃ was evaluated under sunlight irradiation using reactive black-5 (RB-5) dye as the target and exhibited a 90 % reduction in dye concentration within 105 min. The doped Bi₂O₃ nanoparticles exhibited promising photocatalysts for the removal of the dye from wastewater. Recycling experiments were used to verify the stability of the synthesized nanoparticles, and the findings showed promising stability and reusability. The phytotoxicity experiments were performed by the germination of Coriandrum sativum seeds in RB-5 dye, both treated and untreated. In addition, scavenging tests were conducted using reactive species trapping to confirm the presence of the most prevalent reactive species. The prepared semiconductor materials are suitable candidates for environmental remediation.