Green Method for Synthesis of Gold Nanoparticles Using<i> Polyscias scutellaria</i> Leaf Extract under UV Light and Their Catalytic Activity to Reduce Methylene Blue

Abstract

The aqueous fraction of Polyscias scutellaria leaf extract (PSE) has been used as a reducing agent and stabilizer in the green synthesis of gold nanoparticles (AuNPs). UV-Vis spectrophotometry, particle size analyzer (PSA), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy-selected area electron diffraction (TEM-SAED), and X-ray diffraction (XRD) were used to characterize AuNPs. The AuNPs have a size of 5–20 nm and have a face centered cubic (fcc) crystal structure and are stable for 21 days. Phenolic compounds, which are secondary metabolites of PSE, act as an active compound to reduce Au 3+ ion to Au 0 , as well as stabilize the AuNPs through their surface interaction with carbonyl and hydroxyl groups of phenols. AuNPs exhibit excellent catalytic activity for the reduction of methylene blue with NaBH 4 . The reduction of methylene blue using AuNPs catalysts is a pseudo-first-order reaction with a reduction rate constant (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msub><mml:mrow><mml:mi>k</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">o</mml:mi><mml:mi mathvariant="normal">b</mml:mi><mml:mi mathvariant="normal">s</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>) of 0.0223 min −1 .