Interfacial charge transfer in graphene–ZnFe2O4 thin films for efficient photocatalytic degradation of antibiotics under visible light

The removal of pharmaceutical pollutants from water remains a critical environmental challenge, necessitating photocatalytic materials with efficient charge separation and high conductivity. Here, we report the first synthesis of graphene (Gra)–ZnFe2O4 nanocomposite thin films via spray pyrolysis, successfully overcoming the major limitations of pristine zinc ferrite, namely, its wide band gap, low electrical conductivity, and rapid electron–hole recombination through Gra incorporation. The resulting nanocomposite demonstrates promising performance in the photocatalytic degradation of ampicillin, highlighting its potential for pharmaceutical pollutant remediation. The effect of Gra integration was thoroughly confirmed through structural, morphological, optical, and electrical characterization, which revealed strong interfacial contact between Gra and ZnFe2O4 nanoparticles. Gra acts as an electron acceptor and conductive network, enhancing charge separation, suppressing electron–hole recombination, and facilitating electron mobility. Consequently, the optical band gap decreased from 3.01 to 2.77 eV, and electrical resistivity dropped from 187.1 to 177.2 Ω. The optimized nanocomposite achieved 60% degradation of ampicillin under visible light, demonstrating significantly enhanced photocatalytic performance. These results establish Gra–ZnFe2O4 thin films as a scalable, efficient, and sustainable platform for water treatment, combining tunable optical properties, high surface area, and superior charge carrier dynamics.