Gold Nanoparticles from Induced Au3+→Au0 Reaction in Polyvinyl Alcohol Molecules in Presence of Sucrose in Hot Water

In hot water (50–60°C), polyvinyl alcohol (PVA) molecules have coordination reaction with Au3+ cations, forming an Au3+-PVA polymer complex. In the proposed model reaction in small templates, the complex converts to Au0 capping in PVA molecules. Adding sucrose (5–10 times the PVA in mass) in a typical batch promotes Au3+→Au0 reaction, showing absorption coefficient α in Au0 surface plasmon band to be enhanced as much as 28 times the value in reaction with PVA. The band shifts at 547 nm from 566 nm (α = 21.4 cm−1 mol−1) in the PVA sample. Drying Au0-PVA/sucrose (2–5 wt% Au0) colloid at 60–70°C and then heating at 450°C in air burns off the organic part, leaving behind a light ash colored powder with Au0 nanoprisms or nanofibrils (∼30 nm average width). X-ray diffractogram has six reflections, (111), (200), (220), (311), (222), and (400), of Fm3m fcc Au0 of lattice parameter a = 0.4080 nm. The powder has photoluminescence in transversal and longitudinal Au0 plasmon bands of 535 and 585 nm, respectively.