title: Surfactants-aided syntheses of different sizes and triangular shape of gold nanoparticles using trisodium citrate in environmentally friendly and photoinduced methods.
abstract: We prepared gold nanoparticles (Au NPs) by only using trisodium citrate as the stabilizer. The detailed reaction mechanisms of S(N)1 and E1 reactions are examined and evidenced in this study by FTIR data. Citric acid is a kind of tertiary substrate. In aqueous solution, the substitution nucleophile path 1 (S(N)1) reaction and Elimination path 1 (E1) reaction usually occur simultaneously. Chloride ions, the substitution nucleophile, play a very important role to launch the mechanisms of S(N)1 and E1 reactions. Controlling the concentration of the chloride ions with the addition of HCl(aq) according to Le Chatelier theory, the average particle size of Au NPs (5.5 nm) was achieved to overcome the minimum limited size (approximately 10 nm). Two stages of the photoinduced method, aggregation into triangular conglomerates and growth into triangular particles, were determined form TEM observations. This preparation of Au NPs has potential in tuning the size, shape, and mechanism of Au NP formation by using only environmentally friendly trisodium citrate and the photoinduced method.
authors.affiliation: Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Yen Hsun
authors.initials: YH
authors.lastname: Su
authors.forename: Wei Hao
authors.initials: WH
authors.lastname: Lai
authors.forename: Shih-Hui
authors.initials: SH
authors.lastname: Chang
authors.forename: Min Hsiung
authors.initials: MH
authors.lastname: Hon
mesh_terms: D000327:Adsorption; D002712:Chlorides / Q000737:chemistry; D002951:Citrates / Q000737:chemistry*; D004777:Environment; D006046:Gold / Q000737:chemistry*; D007477:Ions; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000379:methods*; D010777:Photochemistry / Q000379:methods; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D002712:Chlorides; D002951:Citrates; D007477:Ions; D013501:Surface-Active Agents; C514290:trisodium citrate; D006046:Gold