Investigation on the Photodegradation Performance of S-Rich g-C3N4/MnO2 Composites for Efficient Removal of Hazardous Dyes From Aqueous Phase

Sulfur (S)-rich g-C₃N₄/α-MnO₂ (α-MnO₂/GCN-S) heterojunction was synthesized using a simple hydrothermal technique, which was effectively utilized for the photodegradation of methylene blue and congo red dyes under visible light illumination. The results of the characterization analysis suggest that the α-MnO₂/GCN-S composite exhibits a high crystalline nature and the heterojunction successfully formed between g-C₃N₄ and α-MnO₂ demonstrates an effective photocatalytic agent for selected hazardous dyes. According to the obtained findings, α-MnO₂/GCN-S composite exhibited outstanding visible light absorption when compared with pure g-C₃N₄ and α-MnO₂ under visible light irradiation. The enhanced photocatalytic performance of the α-MnO₂/GCN-S can be attributed to the effective separation of electron–hole pairs facilitated by g-C₃N₄, along with the improved visible light absorption properties of the S-doped α-MnO₂. The findings indicate that the α-MnO₂/GCN-S composite demonstrates exceptional photocatalytic performance, achieving degradation efficiencies of 91% and 92% for congo red and methylene blue in 30 and 60 min, respectively. On the other hand, the pristine form of GCN-S and α-MnO₂ exhibited lower degradation rates of 51% and 55% for congo red, and 67%, 69% for methylene blue, respectively. These results highlight the capability of α-MnO₂/GCN-S composites to efficiently eliminate harmful dyes from aqueous solutions.