Two-dimensional graphene oxide-iron oxide catalysts for oxidation of sulfides: Synthesis, product analysis, and environmental impact

Abstract

The efficient and sustainable oxidation of organic sulfides is crucial for environmental remediation and the production of specialty chemicals. The unique molecular structure of two-dimensional graphene oxide (GO) enables its application in environmental catalysis, particularly when combined with active metal oxides. This study presents a sustainable synthesis of GO-Fe₃O₄ composites via co-precipitation and wet-deposition methods, forming 15 nm iron oxide nanoparticles uniformly anchored on 200 nm GO sheets. Characterization by TEM, XRD, and FTIR confirmed the crystalline structure and successful integration of Fe₃O₄ onto GO. The composite achieved a thioanisole conversion of 95.8 % in the presence of H₂O₂ and 64.2 % without H₂O₂, under mild conditions (50 °C, 5 h). Photocatalytic studies demonstrated conversions of 89.6 %, 77.7 %, and 75.2 % under UV, sunlight, and visible light, respectively, with a direct band gap reduction from 3.23 eV (GO) to 2.24 eV (GO-Fe₃O₄). These results highlight the interplay of GO's electron mobility and Fe₃O₄ catalytic activity in generating reactive oxygen species (•OH and O₂•⁻) through Fenton and photocatalytic processes. Furthermore, energy and environmental assessments revealed that the synthesis method required only 24.79 kWh/g of catalyst, with a total emission of 10.32 kgCO₂/g catalyst, emphasizing its low carbon footprint and material efficiency. Additionally, this work provides mechanistic insights into the synergistic interactions between GO and Fe₃O₄, advancing the design of 2D carbon-based materials for sustainable sulfur removal and green chemical applications.