Sparking a comparative study between selective Bi-based photocatalysts (BiOCl, Bi12O17Cl2, and CuBi2O4) depending on their photocatalytic characteristics and degradation activity

Bismuth-based photocatalysts have become one of the most widely investigated materials in the photocatalytic fields. In this work, common bismuth-based photocatalysts (BiOCl, Bi₁₂O₁₇Cl₂, and CuBi₂O₄) were perfectly synthesized, and their photocatalytic characteristics were examined and compared over different characteristic technologies (XRD, FT-IR, SEM, TEM, BET, DRS, PL, and EIS). Furthermore, the photocatalytic activity was performed for malachite green (MG) and tetracycline (TC) degradation under LED radiation. Compared with other catalysts, the CuBi₂O₄ exhibited the strongest light absorption towards visible and near-IR regions because it has the narrowest bandgap energy (1.62 eV). However, the small bandgap energy of CuBi₂O₄ promoted the charge recombination rate and hindered their catalytic performance. Besides, the Bi₁₂O₁₇Cl₂ catalysts reflected the highest MG and TC degradation efficiencies of 72.5% and 65.7%, respectively. This is due to the moderate bandgap energy of Bi₁₂O₁₇Cl₂ (2.63 eV), acceptable light absorption, and higher photocarrier separation rate. Moreover, the perfect band structure of Bi₁₂O₁₇Cl₂ allows it to produce ^•OH radicals, accelerating the MG and TC degradation rate. The trapping tests revealed the ability of BiOCl and Bi₁₂O₁₇Cl₂ to yield ^•OH, while the CuBi₂O₄ obtained strong CB potential to produce ^•O₂⁻. Meanwhile, all synthesized photocatalysts returned good recyclability performance after five cycles. Finally, the photo-destruction mechanism has been elucidated through optical, electrochemical, and trapping tests. This work offers valuable insights into tailoring bismuth-based photocatalysts for improved catalytic behavior, paving the way for innovative approaches in sustainable energy and environmental remediation technologies.