Bougainvillea glabra-Mediated ZnO/rGO Nanocomposite for Enhanced Photocatalytic Degradation of Methylene Blue and Antibacterial Activity

The synthesised ZnO/rGO/Bougainvillea glabra nanocomposite demonstrates significant structural and functional modifications due to the incorporation of rGO and plant-derived phytochemicals. A reduction in crystallite size from 28.8 nm to 2-4 nm indicates controlled nucleation and growth during synthesis. Fourier-transform infrared spectroscopy (FTIR) analysis confirms Zn–O bonding along with organic functional groups, evidencing surface modification by plant extract. Morphological analysis reveals a heterogeneous structure, contributing to increased active surface area. The band gap reduction from 3.29 to 3.18 eV suggests enhanced light absorption, likely due to ZnO–rGO interactions facilitating improved electron transfer. Photocatalytic studies show enhanced methylene blue degradation compared to pristine ZnO, attributed to efficient charge separation and reduced electron–hole recombination. The composite retains activity over multiple cycles, indicating good stability. The synthesized nanocomposite also exhibited modest antibacterial activity against the tested bacterial strains, which may be attributed to reactive species generation and surface interactions.