Leaf Extract Templated Synthesis of CoO Nanoparticles for Electrochemical Sensor and Antibacterial Applications.

Green synthesis of metal oxide nanoparticles (NPs) is a viable alternative methodology because of cost-effective and availability of environmentally friendly templates for desired application, which has attracted the attention of researchers in recent years. In the present study, CoO NPs were synthesized in various volume ratios in the presence of leaf extract as a template. The synthesized CoO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), surface area electron diffraction (SAED), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and Fourier transform infrared (FTIR) spectroscopy. XRD analysis found that the average crystalline sizes for the 1 : 2, 1 : 1, and 2 : 1 volume ratios was 25.83, 21.05, and 27.98 nm, respectively. SEM-EDX and TEM analyses suggest that the green-synthesized CoO NPs are spherical in shape without the presence of impurities. The band gap values of the 1 : 2, 1 : 1, and 2 : 1 volume ratios of CoO NPs were found to be 1.83, 1.77, and 2.19 eV, respectively. FTIR analysis confirmed the presence of various bioactive ingredients within the leaf extract of . CoO NPs-modified electrodes showed better sensing capability towards ascorbic acid and citric acid due to enhanced electron transfer kinetics. Among three volume ratios (1 : 2, 1 : 1, and 2 : 1) of CoO nanoelectrodes, 1 : 1 and 2 : 1 were identified as the best performing nanoelectrodes. This is possibly due to the high catalytic behavior and the more homogenized surface structure. CoO (1 : 2) nanodrug showed the enhanced antibacterial activity (16 mm) towards which is attributed to the formation of enhanced reactive oxygen species (ROS).