Bi2O3/MnO2 heterojunction composite prepared by wet-chemical–Hydrothermal route for dye degradation and pathogen inactivation

Abtract Water pollution from organic dyes and pathogenic microorganisms poses significant environmental and health challenges. Herein, we reported Bi2O3/MnO2 composite via low-temperature wet-chemical precipitation followed by hydrothermal treatment for dual photocatalytic dye degradation and antibacterial applications. XRD analysis confirmed the formation of monoclinic α-Bi 2 O3, and α-MnO 2 phases, while SEM revealed successful decoration of rod-like α-Bi 2 O3 with α-MnO 2 nanoparticles. The XPS analysis revealed the new Mn-O-Bi bonding, confirming successful heterojunction formation and electronic coupling between components. The optimal BiMn-12 composite (1:2 molar ratio) demonstrated significantly enhanced photocatalytic performance, achieving 87% and 54% degradation of methylene blue (MB) and methyl orange (MO), respectively ((10 ppm 100 mL, 50 mg of photocatalyst), within 120 minutes under visible light irradiation at a lamp-to-solution distance of 20 cm. The lower MO degradation may be attributed to the greater stability of its azo structure and less favorable adsorption behavior on the catalyst surface. The photocatalytic degradation of Bi-Mn satisfied pseudo-first-order kinetic reaction with rate constants 0.017 min −1 for MB and 0.0065 min −1 for MO. The composite maintained stable performance over three consecutive photocatalytic cycles, demonstrating excellent reusability. Additionally, BiMn-12 exhibited potent antibacterial activity against both Escherichia coli (MIC: 1.25%, MBC: 5%) and Staphylococcus aureus (MIC: 5%), with E. coli showing greater susceptibility. Future studies should focus on optimizing reaction parameters, validating the reactive species mechanism, and assessing the material performance in real wastewater systems. This multifunctional Bi 2 O 3 MnO 2 nanocomposite represents a promising sustainable solution for comprehensive water treatment, simultaneously addressing both chemical and biological contaminants through a single material platform.