Preparation of ZnO nanoflowers for surface enhance Raman scattering applications

Abstract

Thanks to unique Raman spectra of chemical substances, a growing number of applications in environmental and biomedical fields based on Raman scattering has been developed. However, the low probability of Raman scattering hindered its potential development and thus, many different techniques were developed to enhance Raman signal. A key step of surface-enhanced Raman scattering technique is to prepare active SERS substrate from noble metals. The main enhancement mechanism is electromagnetic enhancement resulted from surface plasmon resonance. The disadvantages of nanoparticles based SERS substrates include high randomness due to self - assembly process of nanoparticles. Recently, a new kind of SERS substrates with order nanostructures of semiconductors combining with noble metals can serve as active SERS substrates, which are expected to possess high enhancement of Raman signals. In this study, ordered ZnO nanorods were first prepared by galvanic hydrothermal method and gold was sputtered on the as prepared ZnO nanomaterials to enhance Raman. Our SERS substrates exhibit promising high enhancement factors, and can detect chemical substances at concentration in nano molar range.

Clarifying Contribution of SERS Mechanism Based on Semiconductor Material - ZnO Microtube in Probing Methylene Blue

“…To evaluate the sensitivity of SERS activity of ZnO microtube substrate in detecting MB molecule, various concentrations of MB (ranging from 10 -3 M to 10 -7 M) were implemented. Figure 6a describes the SERS spectra of MB on ZnO microtube surfaces with the lowest concentration of MB could be recognized at 10 -7 M. Therefore, the limit of detection (LOD) of MB using ZnO microtube surface is as low as 10 -7 M. Compared to the previous work also using the same class semiconductor nanomaterial to detect MB [30], the LOD based on ZnO microtube surface is apparently higher than that based on nanorods. However, when compared to the nanocomposit of ZnO nanorod /Au SERS surface, the ZnO microtube substrate has lower sensitivity in detecting MB [31,32].…”