A sulfur-doped alga-like g-C3N4 photocatalyst for enhanced photocatalytic and antimicrobial properties

Abstract

Graphitic carbon nitride (g-C₃N₄) is a non-metallic semiconductor photocatalyst which is widely used in water treatment. Improving the charge separation and transfer efficiency of g-C₃N₄ has been a hot research topic. In this work, a sulfur-doped algal graphitic carbon nitride (SCN) was synthesized by microwave using thioacetamide as an elemental sulfur dopant. The alga-like structure endowed g-C₃N₄ with a higher specific surface area and visible light absorption. Combined with experiments and density functional theory (DFT) calculations, the introduction of S further changed the orbital structure and increased the charge density, leading to a shift of energy level positions as well as enhanced photogenerated electron transport. The combination of morphology adjustment and suitable elemental doping allowed the materials to achieve a significant improvement in the photocatalytic degradation performance of organics and the antibacterial activity. The degradation rate of rhodamine B (RhB) by SCN-60mg reached 0.21873 min⁻¹, which was 12 times higher than that of bulk g-C₃N₄ (BCN). Similarly, SCN-60mg degraded malachite green (MG), neutral red (NR), methyl orange (MO), methylene blue (MB), tetracycline (TC), and ciprofloxacin (CIP) by 100%, 93%, 90%, 97%, 79%, and 86%, respectively, within 30 min. Meanwhile, SCN-60mg still exhibited excellent photocatalytic performance over four degradation cycles. In addition, SCN-60mg showed nearly 100% antibacterial efficiency of Staphylococcus aureus (S. aureus) within 1 hour. This study provides a new idea for fabricating effective photocatalysts for complex wastewater treatment.