A multi-functional novel Z-scheme ZnIn2S4/g-C3N5 heterojunction catalyst for enhanced visible light active photocatalysis and antimicrobial action

Abstract

Photocatalysis represents a sustainable approach for cleaner energy production, wastewater treatment, and antimicrobial disinfection. Creating effective photocatalysts that respond to visible light is crucial for tackling worldwide challenges related to energy and the environment. Here, for the first time, we have reported a facile solvothermal strategy for the in situ growth of ZnIn2S4 nanoflowers on g-C3N5 nanoflakes, where the latter were synthesized via thermal polymerization followed by ultrasonic exfoliation. The resulting ZnIn2S4/g-C3N5 (ZCN-10) composite demonstrated outstanding photocatalytic activity, achieving 88.4% degradation of ciprofloxacin within 90 minutes under solar irradiation and producing 3368 mu M L-1 of H2O2 under visible light. This enhanced performance when compared to pristine ZnIn2S4 and g-C3N5 is attributed to the formation of a direct Z-scheme heterojunction, which promotes efficient charge separation, broadens light absorption, and optimizes the band structure and morphology. The ZCN-10 catalyst maintained high photocatalytic efficiency over four consecutive cycles and also exhibited notable antimicrobial activity, producing a 17 mm inhibition zone against B. subtilis and 30 mm inhibition zone against E. coli. Comprehensive analytical characterization confirmed the successful synthesis and structural integrity of the nanocomposite. Mechanistic studies, including radical scavenging and band structure analysis, revealed that the direct Z-scheme configuration significantly enhances charge carrier separation and utilization, facilitating the generation of reactive species such as superoxide ((center dot)O2-) and hydroxyl ((OH)-O-center dot) radicals, which drive advanced oxidation processes (AOPs). This work highlights a promising route for developing earth-abundant, eco-friendly photocatalysts for environmental remediation and sustainable energy applications.