Abstract
A green route to architecturally complex CuO photocatalysts is highly attractive for integrated water disinfection and pollutant removal. Here we report a plant-extract-mediated precipitation–calcination strategy in which aqueous leaf extracts of Mitragyna parviflora and Leptadenia reticulata direct CuO growth from granular nanoparticles into distinctive fused-prism nanostructures (CMP, CLR). X-ray diffraction confirms phase-pure monoclinic CuO for all samples, while FESEM/TEM reveal the evolution from irregular aggregates (extract-free CuO) to faceted plates (CMP) and densely interlocked prisms (CLR). Diffuse reflectance spectroscopy shows marked band-gap narrowing from 2.32 eV (CuO) to 1.35–1.36 eV (CMP, CLR), accompanied by pronounced photoluminescence quenching and subtle changes in Cu 2p and O 1 s X-ray photoelectron spectra, indicating altered defect structure and surface oxygen speciation. Under natural sunlight, CLR exhibits the highest photocatalytic activity for Rhodamine 6 G, methylene blue and safranine, with apparent rate constants up to 9.81 × 10⁻3 min⁻1 and simultaneously accelerates 4-chlorophenol degradation compared to CMP and extract-free CuO. Agar well diffusion assays against Escherichia coli (EC), Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) reveal significantly enlarged inhibition zones for the plant-derived samples, particularly CLR, evidencing strong antibacterial activity. These results demonstrate that medicinal plant extracts act as multicomponent structure- and defect-directing media for CuO, yielding fused-prism architectures that couple enhanced visible-light photocatalysis with efficient antibacterial performance.