Supplementary Information
A facile approach for deposition of gold nanoparticles on C60 microcrystals with unique shapes
Zhenquan Tan,*aAkitoMasuhara,b Hitoshi Kasai,cHachiroNakanishic and Hidetoshi Oikawac
a Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka, Japan. Fax: +81668794370; Tel: +81668794370; E-mail:
b Graduate School of Science and Engineering, Yamagata University, Jonan 4-3-16, Yonezawa, Yamagata, Japan.
c Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, Japan
Fig. S1 Raman spectra of gold nanoparticles, C60 MCs, and gold-coated C60 MCs excited by 532 nm Laser.Gold nanoparticles have no Raman absorption at the measured range. Bare C60 MCs showed a characteristic Ag(2) Raman vibration mode at 1467 cm-1. This Raman absorption peak was slightly shifted to 1463 cm-1 when gold nanoparticles coated on the surface of C60 MCs. The shift of Ag(2) mode from high to low energy region indicates the charge transfer from gold nanoparticles to C60 MCs. The result is in good agreement with the XPS result. The Raman spectroscope was calibratedusing the 520 cm-1 characteristic peak of Si.
Fig. S2Absorption spectra of ethanol+HAuCl4under stirring at room temperature.
0.5 ml of HAuCl4 aqueous solution (0.02 M) was mixed with 10 ml of ethanol. The mixed solution was continued to stir at room temperature for 24 hours. The absorption spectroscopy was measured in various reaction times: 0, 1, 2, 4, 6, 8, 12, 16, 20, 24 hours. During the stirring, there was not any absorption peak observed in the wavelength ranged from 480 nm to 800 nm. It proves that goldnanoparticles can be not produced from the reaction of ethanol+HAuCl4 under our experimental conditions.
Fig. S3Absorption spectra of ethanol+CS2+HAuCl4 under stirring at room temperature.
200 ml of CS2 was mixed with 10 ml of ethanol. 0.5 ml of HAuCl4 aqueous solution (0.02 M) was added into the above mixed solution. Afterword, the mixed solution was treated for stirring at room temperature for 24 hours. The absorption spectroscopy was measured in various reaction times: 0, 1, 2, 4, 6, 8, 12, 16, 20, 24 hours. During the stirring, there was a newbroaden peak appeared near 550 nm,which is generally assigned to the plasmon absorption of goldnanoparticles. It indicates the formation of goldnanoparticlesfrom the reaction of ethanol+CS2+HAuCl4 under stirring at room temperature. Hence, CS2 must play a critical role in the HAuCl4 reduction.
Fig. S4 XRD patterns of the products obtained from the ethanol-CS2-HAuCl4 reaction under stirring for 2 hours at 20 ºC and 40 ºC in a complete dark room. The production of gold nanoparticles in dark room indicated that the reaction mechanism was not a photo-reduction reaction.
Fig. S5(a) UV-Vis absorption spectra and(b) XRD pattern of gold nanoparticles produced from HAuCl4 + Na2S reaction at room temperature in the absence of C60 MCs.
A new absorption peak appeared at 550 nm, indicating the formation of gold nanoparticles. The absorption maximum of this peak shifted to long wavelength region with the reaction time, which suggests that the size of gold nanoparticles grows with the reaction time. On the other hand, the characteristic absorption of HAuCl4 at 320 nm gradually reduced with the reaction time, which indicates the reduction of HAuCl4 by S2+ ions. XRD patterns clearly showed the diffraction peaks of Au (111), (200), (220), and (311).
Fig. S6XRD patterns of gold nanoparticles prepared fromthe methanol-CS2-HAuCl4 reaction under stirring for 2 hours at various temperatures (a) in the absence of C60 MCs, and (b) in the presence of C60 MCs. Gold nanoparticles were produced at low given temperature (20 and 40 ºC).