Facile synthesis of copper oxide nanoparticles using Piper chaba stem extract: Photocatalytic efficiency and antibacterial potential

In this work, a phytochemical ( Piper chaba stem extract)-assisted precipitation method was employed to obtain crystalline CuONPs. UV–Vis spectroscopy displayed a characteristic absorption peak at 344 nm, and Tauc plot analysis revealed a wide optical band gap of 3.23 eV. FTIR analysis confirmed Cu–O bond vibration at 625 cm –1 , while EDX spectrum verified elemental composition containing 52% Cu and 18% O. Zeta potential analysis exhibited a surface charge of –21.2 mV, confirming good colloidal stability via electrostatic repulsion. XRD verified a single-phase monoclinic structure (JCPDS No. 48–1548) with an average crystallite size of 15.3 nm, lattice micro-strain of 5.54 × 10 –3 , and dislocation density of 5.48 × 10 15 m –2 . FE-SEM revealed predominantly spherical morphology with a mean particle size of 80 nm. The bio-synthesized CuONPs demonstrated potent antibacterial activity against key Gram-negative ( Salmonella typhi, Vibrio cholerae, Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) pathogens. Additionally, the nanoparticles exhibited high solar photocatalytic performance, achieving 87% degradation of Congo red (CR) dye within 160 min following pseudo-first-order kinetics (k = 0.0118 min –1 ). Overall, this sustainable bio-mediated approach yields multifunctional CuONPs well-suited for wastewater remediation and biomedical applications.