Synergistic engineering of CuO/GO/Fe 3 O 4 ternary nanocomposites for enhanced visible-light-driven photocatalytic degradation of methylene blue

CuO nanoparticles (CuO NPs), graphene oxide (GO) nanosheets, and Fe3O4 NPs were synthesized by electrosynthesis, a modified Hummers’ method, and co-precipitation followed by hydrothermal treatment, respectively, to fabricate binary CuO/GO and ternary CuO/GO/Fe3O4 nanocomposites (NCs). These materials were applied as photocatalysts and adsorbents for methylene blue (MB) removal under visible light irradiation. Compared with pure CuO, CuO/GO NCs exhibited significantly improved photocatalytic activity, achieving ∼70% MB degradation within 120 min, while pure CuO reached only ∼20%. Notably, the ternary CuO/GO/Fe3O4 NCs demonstrated superior performance, achieving ∼95–100% degradation within 60–80 min and following pseudo-first-order kinetics with a rate constant of 61.7 × 10−3 min−1, approximately 32 and 5.6 times higher than those of pure CuO and CuO/GO NCs, respectively. This remarkable enhancement is attributed to the synergistic effects of efficient dye adsorption, improved electron transport, and enhanced charge separation, highlighting its strong potential for sustainable wastewater treatment.