Layered ZnO/MgO Nanohybrids for Photocatalytic Caffeine Degradation

This study presents the successful development of layered ZnO/MgO nanohybrids via a novel, sustainable one-pot, low-cost, low-temperature route using combined Zn-based (glycerol-urea) and Mg-based (isopropanol-glycerol) hydrogels. This method represents a significant advance in green chemistry by yielding a high-performance hybrid material without the use of noble metal nanoparticles or toxic surfactants. Comprehensive analysis using X-ray diffraction (XRD), electron microscopy (TEM/SEM), and UV-vis spectroscopy confirmed the formation of a ZnO/MgO heterostructure dominated by nanorods. The nanorod morphology offers structural advantages by increasing the specific surface area and minimizing agglomeration, essential for maximizing catalytic efficiency. Furthermore, microstructural analysis revealed that the optimal ZM 3-1 sample possesses high dislocation densities in both crystalline phases, validating the engineered electronic properties and suppressed crystalline defects required for enhanced photocatalytic activity. When evaluated using caffeine degradation as a technical metric, and since it is an emergent pollutant, the ZM 3-1 nanohybrid demonstrated a substantial synergistic effect, achieving 64% degradation in 120 min, which is nearly two times greater than the efficiency of pure ZnO. This superior performance resulted in significantly accelerated reaction kinetics, comparable to those reported for conventional noble metal-based photocatalysts, highlighting the technical merit of this metal-free, structurally optimized material for advanced oxidation processes.