Copper 2 chloride

Tert-dodecylmercaptan, dodecanethiol, tin (IV) chloride (SnCl4•5H2O), zinc oxide (ZnO), copper (II) chloride (CuCl2•2H2O), silver nitrate (AgNO3), 1-octadene (ODE), oleylamine (OLA, 70%), and oleic acid (OA, 90 %) were purchased from Aldrich. Chloroform, isopropanol, tetrahydrofuran (THF), toluene and methanol were of analytical grade and obtained from various sources. OLA was distilled before its use. The rest of the precursors and solvents where used without further purification.

For the preparation of Cu nanocrystals, 0.341 g (2 mmol) of copper(II) chloride (Aldrich) and 0.845 g (4.8 mmol) of ascorbic acid was dissolved in 30 mL of methylformamide (Aldrich) in a 100 mL flask equipped with a reflux condenser. The reaction mixture was stirred under purging with argon at room temperature for 30 min and heated to 90 °C for 12 h. The solution was cooled to room temperature and mixed with 70 mL of ethyl acetate to flocculate Cu nanocrystals. Cu nanocrystals were recovered by centrifugation and repeatedly purified by dispersing in water and precipitating with tetrahydrofuran. TEM imaging showed particles of between 2 and 3 nm diameter, consistent with the absence of visible plasmon absorption that indicates particle size smaller than 5 nm. [35] When exposed to air, the brown particle color did not turn greenish as would be the case if oxidation had resulted in the formation of Cu II . At the same time, the presence of some Cu I surface sites was indicated by the observation of the characteristic CO infrared band at 2113 cm -1 [36] when bubbling CO gas through an aqueous colloidal particle solution. This band disappeared upon visible light photosensitization of the Cu particles due to re-reduction to Cu 0 , which binds CO molecules more weakly than Cu I .