Enhanced Photocatalytic Activity of Bio-Mediated Ag@Cu₂O NPs Towards Fampridine: Kinetic Modelling and Mechanistic Pathways

To enhance the photocatalytic activity of Cu₂O NPs, Tabernaemontana divaricata leaf extract was used to synthesize Ag@Cu₂O NPs. The synthesized Ag@Cu₂O NPs were characterized using UV–Vis, XPS, XRD, and HR-TEM. The mechanism of Ag onto Cu₂O NPs showed that the plant extract was fully saturated with flavonoids and can implant Ag onto Cu₂O NPs. XPS spectra showed a shift towards lower binding energy for Cu 2p peaks from 932 to 931 eV and 952 to 951 eV, which confirmed the formation of Ag@Cu₂O NPs. HR-TEM investigation indicated that the lattice distance was d = 0.25 nm which corresponds to the (111) plane of Ag, hence demonstrating the fabrication of Ag@Cu₂O NPs. The degradation efficiency of fampridine was enhanced using Ag@Cu₂O NPs to 95% with 97% chemical oxygen demand (COD) removal and 75% total organic carbon (TOC) conversion after 210 min of reaction time compared to Cu₂O NPs. The modified first-order kinetic (MFOK) model was well fitted for the TOC conversion of fampridine, with R² = 0.99 as compared to the first-order kinetic (FOK) model. Liquid chromatography–mass spectroscopy (LC–MS) spectra for the degradation of fampridine showed ten intermediate fragments. The synthesized Ag@Cu₂O NPs also showed a high inhibition zone for the two different bacterial pathogens.