Electrochemical Synthesis and Photocatalytic Evaluation of Fe 3 O 4 /ZnO/Graphene Nanocomposite for Thiazine Dye Degradation in Simulated Wastewater
Mohamed S. Mahmoud, Sulaiman Al Isaee, Mohamed B. Mihoub, Makki Abdelmouleh, Afaf Ghais, Khawla Al Zufaiti, Aisha Al Wahshi, Zahra Al Maamri, Al Yamamah Al Mawaali, Amal Al Badi, Ilyes JedidiABSTRACT
Developing scalable, energy‐efficient photocatalysts that couple high degradation performance with easy post‐treatment recovery remains a critical challenge in industrial wastewater remediation. Here, we report a one‐pot electrochemical route that simultaneously exfoliates graphene, nucleates ZnO nanorods (with lengths of 384–1000 nm and diameters of 30–105 nm), and anchors Fe 3 O 4 nanoparticles to form a ternary Fe 3 O 4 /ZnO/graphene nanocomposite. This integrated top‐down/bottom‐up approach offers a green, surfactant‐free, and industrially scalable process, achieving a quantified energy consumption of 16.0 Wh g − 1 graphene, thereby establishing a benchmark for future scale‐up studies. Several characterization techniques like Fourier‐transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy (SEM‐EDX), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), photo luminacins (PL), and ultraviolet‐visible spectrophotometer (UV–Vis) confirm the formation of a well‐coupled heterostructure with an optical bandgap of 2.7 eV, where graphene enhances charge separation, ZnO provides strong photon absorption, and Fe 3 O 4 enables magnetic separability. The optimized nanocomposite achieves ∼90% degradation of thiazine dye (methylene blue, initial concentration of 10 ppm) within 60 min under solar irradiation, demonstrating excellent structural and catalytic resilience with 87.2% degradation retention across five reuse cycles. Advanced kinetic modeling using nonlinear least squares (NLLS) reveals that degradation follows a diffusion‐controlled pseudo‐second‐order mechanism, offering rare mechanistic clarity for Fe 3 O 4 /ZnO/graphene photocatalysts. Collectively, the results highlight this electrochemical synthesis strategy as a next‐generation, energy‐aware, magnetically recoverable platform for sustainable dye wastewater treatment.