Cu-Mediated Structural Regulation of GO-Derived rGO/α-Fe2O3 Nanocomposites for Photocatalytic Degradation of Organic Pollutants

Abstract A GO/Cu–Fe carbon–metal oxide composite photocatalyst was synthesized via a facile one-pot hydrothermal method in aqueous media. Cu2+ addition was essential for forming uniform spherical particles of approximately 800 nm with densely textured surfaces. FIB cross-sectional analysis revealed an intimately integrated architecture with homogeneously distributed GO-derived rGO. XRD confirmed the formation of crystalline α-Fe2O3 without detectable crystalline Cu-containing secondary phases, suggesting that Cu species were highly dispersed or structurally disordered. Raman and XPS analyses verified extensive in situ reduction of GO to rGO, yielding an sp2 carbon fraction of 81.8% and an electrical conductivity of 1.87 × 10–4 S·cm–1. Comparative photocatalytic tests showed that, under UV–vis irradiation, the GO-derived rGO phase primarily contributed to photocatalytic activity, whereas under visible light irradiation, cooperative interactions between Cu species and rGO are proposed to play a key role. The GO/Cu–Fe composite achieved ∼80% methyl orange removal, compared with ∼30% removal by single-component analogues. Band structure analysis, with VB and CB potentials of +0.07 V and −2.04 V vs NHE, respectively, together with radical scavenger tests, indicated that •OH generation mainly proceeded through Fe3+/Fe2+-mediated Fenton-like redox processes rather than direct hole oxidation. The composite retained approximately 90% efficiency after 10 cycles, exhibited broad-spectrum pollutant removal, maintained performance in 2 M NaCl, and achieved complete methyl orange degradation in a sponge-immobilized configuration, demonstrating its practical potential for wastewater remediation.