Surface-enhanced Raman scattering of molecules adsorbed on Co-doped ZnO nanoparticles
Article first published online: 18 MAY 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Volume 43, Issue 1, pages 61–64, January 2012
How to Cite
Xue, X., Ruan, W., Yang, L., Ji, W., Xie, Y., Chen, L., Song, W., Zhao, B. and Lombardi, J. R. (2012), Surface-enhanced Raman scattering of molecules adsorbed on Co-doped ZnO nanoparticles. J. Raman Spectrosc., 43: 61–64. doi: 10.1002/jrs.2988
- Issue published online: 27 JAN 2012
- Article first published online: 18 MAY 2011
- Manuscript Accepted: 17 APR 2011
- Manuscript Received: 3 JAN 2011
- charge transfer
Transition-metal-doped semiconductor nanoparticles (NPs) have been well studied for their optical and catalytic properties but seldom studied by surface-enhanced Raman scattering (SERS). In this paper, transition-metal-doped semiconductor NPs are investigated for their SERS property. Four groups of Co-doped (0.5, 1, 3, and 5%) ZnO (CoZnO) NPs and pure ZnO NPs were synthesized and studied. When 4-mercaptobenzoic acid was used as probing molecule, significant SERS signals were obtained on all the five samples. Moreover, it is very interesting to observe a relationship between the Co-doping concentration and enhancement of the SERS signals. SERS intensities first increase with doping concentration (up to 1%), and then decrease with further increase in doping concentration (up to 5%). Charge transfer (CT) is considered to be the main contribution to this phenomenon. Different CT ratios from substrates to molecules seem to induce different intensities of the SERS signals. In our experiments, the crystalline defects of CoZnO NPs caused by the Co dopant affect the CT ratios. A possible mechanism of CT from the valance band of CoZnO NPs to the lower unoccupied molecular orbital of the molecules via energy of the surface states is suggested. X-ray photoelectron spectra, UVvis spectra, and Raman spectra were used to characterize the structure and defects in CoZnO NPs. Copyright © 2011 John Wiley & Sons, Ltd.