Facile Synthesis of g-C₃N₄/MnO₂Composites with Dual Functional Activity of Photodegradation of Pollutants and Antimicrobial Efficacy

Increasing environmental contamination and spread of drug-resistant microbials leading to water pollution and antimicrobial resistance is a critical issue worldwide. This study describes the synthesis of multifunctional heterojunction g-C₃N₄/MnO₂ composite as a potential photocatalyst for environmental remediation and microbial inactivation under visible light. Initially, graphitic carbon nitride (g-C₃N₄) was prepared by a thermal polycondensation method. Further, the multifunctional heterojunction g-C₃N₄/MnO₂ composite with uniform MnO₂ nanoparticle (NP) distribution is developed via a simple hydrothermal process. The g-C₃N₄/MnO₂ composites were examined through the degradation of tetracycline (TC) and methylene blue (MB). As a result, the composite materials demonstrated superior photocatalytic efficiency than MnO₂ and g-C₃N₄, due to the composite materials’ enhanced charge separation and extended to the visible light region. Remarkably, degradation efficiencies of 95.38% for MB and 91.97% for TC were achieved within 180 min. Further, antibacterial activity was tested against Escherichia coli and Staphylococcus aureus using the agar–agar well diffusion method. The obtained zone inhibition values reveal that as-prepared g-C₃N₄/MnO₂ composites have strong antimicrobial properties. These results demonstrate that g-C₃N₄/MnO₂ composites are cost-effective, sustainable, and multifunctional materials with promising applications in wastewater treatment through simultaneous degradation of organic pollutants and microbial inactivation.