Influence of various concentrations of chloroauric acid on the fabrication of gold nanoparticles: Green synthesis using Elaeis guineensis Jacq leaf extract and characterizations

This work studies a green method for synthesizing gold nanoparticles (AuNPs) using Elaeis Guineensis Jacq. (oil palm) leaf extract (EGE) using a precursor of chloroauric acid (HAuCl 4 ). The influence of various HAuCl 4 concentrations on the formation of AuNPs by the green method was investigated. Characterization methods were employed to analyze the optical properties, size, shape, structure, and SERS applicability of the AuNPs. The findings suggest that EGE contains biomolecules like flavonoids and phenols, which fulfil the roles of reducing and capping agents during the synthesis of AuNPs. The AuNPs were fabricated spectroscopically at around 525 nm and validated by UV–Vis spectrophotometer. FT-IR result presents that the stretching vibrations of the hydroxyl (O–H) molecule are indicated by the large peak absorption at 3336 cm −1 , demonstrating the O–H functional groups in the derivatives of phenols. The carbonyl (C O) stretching vibrations, generated by the carboxylic acid in flavonoids and phenols, exhibited a robust absorption at 1602 cm −1 . An optimal HAuCl 4 concentration of 0.69 mM resulted in AuNPs with uniform spherical morphology and a 10–30 nm size range confirmed by TEM analysis. This concentration also led to the strongest Raman intensity, indicating the potential of these biogenic AuNPs for SERS applications. Overall, the study demonstrates a sustainable and efficient method for AuNP synthesis using a readily available plant extract, paving the way for their use in advanced sensing technologies.