Interfacially engineered SnS2@g-C3N4, and NiS2@g-C3N4 heterostructures with morphology dependent charge separation under visible light.

Interfacial engineering plays a crucial role in regulating charge separation and photocatalytic activity in semiconductor heterostructures. In this work, SnS2 and NiS2 were deposited onto pre-synthesized g-CN4 through a one-pot hydrothermal method, yielding flower-like SnS2@g-C3N4 (SGC) and granular NiS2@g-C3N4 (NGC) composites, respectively. XRD, FTIR, and EDX confirmed successful composite formation with integration of metal sulfides with g-C3N4. UV-vis results showed a reduction in band gap from 2.62 eV to 2.37 eV (SGC) and 2.20 eV (NGC). Their performance toward rhodamine B (RhB) and methylene blue (MB) in a mixed-dye system was examined under visible light. Both materials achieved high degradation efficiencies, with SGC yielding 99.9% (MB) and 86.8% (RhB) and NGC achieving 99.4% (MB) and 92.1% (RhB). The superior performance of SGC compared to NGC despite its larger band gap indicates that morphology driven charge separation, rather than band gap reduction alone, manages the photocatalytic behavior of the two composites. Radical-scavenging tests revealed superoxide radicals as the dominant species. The distinct flower-like and granular architecture contributed to improved charge separation and rapid degradation. The composites maintained stable performance over five cycles, demonstrating strong promise for treating pollutants with similar energetic characteristics.