Surface-enhanced Raman scattering (SERS) technology is a cutting-edge analytical tool for molecule detection. Attractive SERS performance has been achieved on noble metal nanostructures;however these substrates usuall...
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Surface-enhanced Raman scattering (SERS) technology is a cutting-edge analytical tool for molecule detection. Attractive SERS performance has been achieved on noble metal nanostructures;however these substrates usually suffer from difficulties of direct adjusting of the physical structures to achieve tunable SERS performance. Studies on semiconductor oxides have revealed that attractive SERS performance can be obtained on them, but strategies of engineering material properties for SERS performance improvement still pose a challenge. Here, an electrically programmable SERS substrate is prepared by depositing hydrothermally synthesized MoOx/Ag hybrids within electrodes as the SERS active region. In the experiment, an electrical field is applied on the electrodes to regulate Ag+ ion migration and redeposition in the MoOx solid electrolyte. Through adjusting the leakage current level, the size of the Ag nanoparticles in the MoOx/Ag hybrids is electrically controlled. The SERS performance of the substrate is evaluated using rhodamine 6G as the Raman reporter. The results evidence that Raman enhancement factors of 1.13 x 10(5), 4.75 x 10(5), and 1.04 x 10(6) can be obtained by programming the leakage current level to 10(-7), 10(-5), and 10(-3) A, respectively. A maximum detection limit of 10(-8) m is achieved on the 10(-3) A substrate.
Surface-enhanced Raman scattering (SERS) has been widely established as a powerful analytical technique in molecular fingerprint recognition. Although conventional noble metal-based SERS substrates show admirable enha...
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Surface-enhanced Raman scattering (SERS) has been widely established as a powerful analytical technique in molecular fingerprint recognition. Although conventional noble metal-based SERS substrates show admirable enhancement of the Raman signals, challenges on reproducibility, biocompatibility, and costs limit their implementations as the preferred analysis platforms. Recently, researches on SERS substrates have found that some innovatively prepared metal oxides/chalcogenides could produce noble metal comparable SERS enhancement, which profoundly expanded the material selection. Nevertheless, to tune the SERS enhancement of these materials, careful experimental designs and sophisticated processes were needed. Here, an electrically tunable SERS substrate based on tungsten oxides (WO3-x) is demonstrated. An electric field is used to introduce the defects in the oxide on an individual substrate, readily invoking the SERS detection capability, and further tuning the enhancement factor is achieved through electrical programming of the oxide leakage level. Additionally, by virtue of in situ tuning the defect density and enhancement factor, the substrate can adapt to different molecular concentrations, potentially improving the detection range. These results not only help build a better understanding of the chemical mechanism but also open an avenue for engaging non-noble metal materials as multifunctional SERS substrates.
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