Mechanistic Investigation of Synergistic Visible-Light-Driven Organic Pollutant Degradation via Dual S-Scheme g-C <b> ₃ </b> N _<b>4</b> /ZnS/MoO _<b>3</b> Heterojunction with Bifunctional Redox Pathways

To address the limitations of conventional heterojunction photocatalysts in carrier recombination and redox potential loss, this study designed a dual S-scheme heterojunction g-C₃N₄/ZnS/MoO₃ system via a hydrothermal route for visible-light-driven organic pollutant degradation. Comprehensive structural analyses (XRD, SEM, TEM, FTIR, XPS, UV-vis-NIR, DFT) verified the formation of a hierarchically ordered architecture with interfacial electronic coupling. The optimized GZM-2 composite demonstrated remarkable photocatalytic activity, degrading 98.31% of MB within 48 min under visible light─10.34, 5.69, and 3.09 times faster than pristine g-C₃N₄, ZnS, and g-C₃N₄/ZnS, respectively. Stability tests revealed an efficiency retention of 84.54% after four cycles, underscoring its robustness. Mechanistic studies attributed the enhanced performance to a dual S-scheme charge transfer pathway, where staggered band alignment spatially separated high-energy electrons from MoO₃ (CB) to g-C₃N₄ (VB) and ZnS (VB), synergistically suppressing recombination while maximizing redox potentials. This study offers a generalized framework for engineering multichannel heterojunction systems to address environmental contamination challenges.