Dual Functional Mn‐Doped Co 3 O 4 Nanoparticles for Efficient Crystal Violet Photodegradation and Antibacterial Applications

In this work, Mn‐doped cobalt oxide nanoparticles were developed as a multifunctional material to address the dual challenge of dye pollution and microbial contamination in wastewater. A series of Mn‐doped Co 3 O 4 nanoparticles with varying Mn concentrations (1%, 2.5%, 5%, and 7.5%) was synthesized via a cost‐effective coprecipitation method to investigate the influence of doping on their functional properties. XRD analysis confirmed the successful substitution of Mn into the Co 3 O 4 lattice. FESEM images revealed a morphological transition from hexagonal to spherical structures upon doping. UV–vis spectra exhibited a redshift with doping, and Tauc plot analysis showed a reduced bandgap, with 5% Mn‐doped Co 3 O 4 displaying 1.52 eV compared to 2.26 eV for pure Co 3 O 4 . BET measurements indicated a substantial rise in specific surface area, while photoluminescence spectra confirmed higher defect densities with increasing Mn content. Photocatalytic tests showed that the 5% Mn‐doped Co 3 O 4 achieved 91.02% and 96.65% crystal violet degradation under UV and visible light, respectively. In addition to photocatalysis, the 5% Mn‐doped Co 3 O 4 exhibited notable antibacterial activity, producing inhibition zones of 25 mm against Staphylococcus aureus and 21 mm against Escherichia coli , demonstrating its multifunctional potential in environmental remediation and antimicrobial applications.