Facile Synthesis of g-C ₃ N ₄ /MnO ₂ Composites 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 <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> 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.