Hybrid single visible nanoreactor for in situ SERS monitoring of plasmon- driven and small Au nanoparticles catalyzed reactions

Experiments Materials Toluene, NaBH 4 , AgNO 3 (99+ %) and poly(vinyl pyrrolidone)(K-30) were purchased from Sinopharm Chemical Reagent Co. Ltd. China. Ethylene glycol (anhydrous, 99.8%), 4-aminothiophenol (4-ATP) and crystal violet (CV) were purchased from Sigma-Aldrich. All chemicals used in this study were of analytical grade. HAuCl 4 • 3H 2 O was obtained from Shanghai Chemical Co. Ltd. China. Tetraoctylammonium bromide (TOAB) was purchased from Adamas Reagent Co. Ltd. Dimethylaminopyridine (DMAP) was purchased from K Chemical Ltd. All the solutions were prepared in double distilled water. The synthesis was carried out according to the literature 1 with a small modification. A typical experiment to synthesize positive charged Au NPs was as follows: 7.4 mL HAuCl 4 (1%) solution was added to a solution of tetraoctylammonium bromide (25 mM) in toluene (16 mL). The transfer of the metal salt to the toluene phase can be clearly seen visually within a few seconds. Following, the freshly prepared 5 mL NaBH 4 (0.4 M) was added to the stirred mixture, which caused an immediate reduction to occur. After 30 min the two phases were separated and the toluene phase was subsequently washed with H 2 SO 4 (0.1M), NaOH (0.1 M) and H 2 O (three times). An aqueous 0.01M 4-dimethylaminopyridine (DMAP) solution (1 mL) was added to aliquots (5 mL) of the as-prepared nanoparticles mixtures, and set for 12 h. Then the Au NPs was transferred from organic phase to aqueous phase. Finally, after removing the organic phase, the aqueous phase was diluted to 10 mL with ultra-pure water. The synthesis was carried out according to the literature. 2 Briefly, EG (10 mL) was firstly refluxed in a three-necked round-bottom flask at 160℃ for 2 h, and then 5 mL EG solution of 0.1M AgNO 3 and 5 mL EG solution of 0.2M poly(vinyl pyrrolidone) (PVP, K-30) were simultaneously injected into the refluxing solvent, at a rate of 0.2 mL/min. The reaction continued at 160℃ for 60 min. Finally, the 1mL as prepared Ag NWs was washed with acetone (9 mL) for 2 times, and water (10 mL) for 3 times.