Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method.

Chih-Shan Tan,Hung-Ying Chen,Lih-Juann Chen,Hsueh-Szu Chen,Shangjr Gwo

doi:10.1038/srep13759

Abstract

For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution.

Highlights

Copper chloride aqueous solution drop was first dripped on surface-enhanced Raman scattering (SERS) substrates with a micropipette
The maximum SERS enhancement factor (EF) is a maximum localized charge density wave amplified on a specific positions and the average SERS EF is an average charge density wave amplified on the surface
The intermediate states of copper chloride aqueous solutions have been investigated with density functional theory, ab initio methods, extended X-ray absorption fine structure (EXAFS), Minuit X-ray absorption near-edge structure (MXAN) and UV-vis-near IR optical absorption spectroscopy previously[25,26,27,28]

Summary

Introduction

A facile in situ surface-enhanced Raman scattering (SERS) technique was developed for the investigation of dynamical changes in copper chloride dihydrate crystallization process in CuCl2 aqueous solution. We show a facile method to investigate the dynamic change of bonding of transition metal ions, Cu2+, and emphasize the in-situ SERS observation as a facile technique for the observation of dynamic changes of intermediates in a variety of chemical reactions in solution.

Results

Conclusion