Abstract
The larger volume to surface ratio and lower energy density of Metal nanoparticles interface with other molecules are advantageous compared to their bulk metal counterparts, the synthesis of gold nanoparticles using chemicals like sodium citrate (NaC_6 H_5 O_7) and sodium borohydrate (NaBH4) as reducing agents has some limitations. In this work, the leaves extract of Moringa oleifera were used as a reducing agent to create a gold metal nanoparticle, and the electrochemical potentials of the resultant AuNPs were assessed. The produced nanoparticles were typically studied by means of a variety of characterization techniques, such as energy dispersive X-ray, scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-Vis), and X-ray diffraction (XRD). The EDX spectrum displays distinct Au peaks, which are attributed to AuNPs, according to the characterization results. The XRD results show that the AuNPs possess crystalline face-centred cubic (FCC) lattice structures. SEM images displayed an array of bright spherical AuNPs. The XRD pattern showed diffractive peaks at 37.8o, 44.2o, 66.4o, and 77.6o, which, in turn, correspond to Bragg's reflection from the Au crystalline plane diffractions (111), (200), (220), and (311), respectively. Variable experimental parameters such pH, temperature, plant extract volume, and gold ion concentration were assessed. The outcomes demonstrated that the optimal quantity required to convert 40mL of Au+ ions to Au atoms at 75℃ in 10 minutes in neutral medium (pH 7) is 10mL of extract from moringa oleifera leaves. The nanoparticle altered the surface of a screen-printed electrode (SPE), and the electrochemical potential of the nanoparticle was assessed using the altered electrode. Results of the electrochemical studies revealed that the nanoparticle has increased the electrochemical and electro-active surface area of the SPE. Thus, it is suggested that the synthesized nanoparticle can be used as a modifier of electrodes for electrochemical analyses.

Key words: Metal nanoparticle, AuNPs, Moringa oleifera, Leaves extract, Electrochemical, Characterization.