Tertiary heterojunction TiO2-Fe3O4/rGO composites for visible light-enhanced degradation of organic dyes in wastewater

Water pollution caused by organic dyes remains a critical global challenge, requiring innovative and sustainable solutions. In this study, we introduce a novel tertiary heterojunction photocatalyst, TiO₂-Fe₃O₄/rGO, synthesized via a hydrothermal method, specifically designed for efficient visible-light-driven degradation of methylene blue (MB). Unlike conventional photocatalysts, the TiO₂-Fe₃O₄/rGO composite integrates TiO₂, Fe₃O₄, and reduced graphene oxide (rGO) to form a synergistic heterojunction, which significantly enhances charge carrier separation and accelerates electron transfer. Advanced characterizations, including XRD, FTIR, SEM, TEM, EDX, and UV–Vis spectroscopy, confirm its optimized structural, morphological, and optical properties. The TiO₂-Fe₃O₄/rGO photocatalyst demonstrates exceptional degradation efficiency, exceeding 95 % within 120 min, and retains over 85 % activity after four consecutive cycles, showcasing its outstanding stability. This remarkable performance is driven by the synergistic interaction between TiO₂, Fe₃O₄, and rGO, which boosts reactive oxygen species (•O₂⁻, •OH) generation. As a cost-effective, robust, and scalable material, TiO₂-Fe₃O₄/rGO offers a promising solution to the challenge of organic dye pollution in wastewater treatment. This study highlights the transformative potential of tailored heterojunction photocatalysts, paving the way for sustainable water treatment technologies driven by visible light.