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چکیده
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The role of pH in the green synthesis of Gold nanoparticles (AuNPs) is investigated. For the reduction synthesis of AuNPs we use HAuCl4.3H2O, sodium hydroxide and starch respectively to serve as precursor, accelerator, reducing agent and stabilizer. The effect of NaOH addition on the nature of AuNPs is systematically studied. The aqueous sol of AuNPs prepared at different pH values display different surface plasmon resonance (SPR) behavior. this is explained in terms of size and size distribution of AuNPs. Materials used to synthesize nanoparticles were HAuCl4.3H2O, Starech, and NaOH. 2 ml aqueous solution of HAuCl4.3H2O (0.2M) was taken in a flask and 50 ml of a 0.2% (wt) starch was added to this solution. Now different amounts of NaOH (0.02M) were added to prepare different sample (3 ml, 5 ml). these solution were heated at 80 °C. The characterization of sample was done by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectrophotometer [1, 2]. The UV–visible spectra and X-ray diffractograms at different pH are shown in fig 1, 2.
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