ABSTRACT
Surface-enhanced Raman scattering (SERS) is a sensitive and fast technique for sensing applications such as chemical trace analysis. However, a successful, high-throughput practical implementation necessitates the availability of simple-to-use and economical SERS substrates. In this work, we present a robust, reproducible, flexible and yet cost-effective SERS substrate suited for the sensitive detection of analytes at near-infrared (NIR) excitation wavelengths. The fabrication is based on a simple dropcast deposition of silver or gold nanomaterials on an aluminium foil support, making the design suitable for mass production. The fabricated SERS substrates can withstand very high average Raman laser power of up to 400 mW in the NIR wavelength range while maintaining a linear signal response of the analyte. This enables a combined high signal enhancement potential provided by (i) the field enhancement via the localized surface plasmon resonance introduced by the noble metal nanomaterials and (ii) additional enhancement proportional to an increase of the applicable Raman laser power without causing the thermal decomposition of the analyte. The application of the SERS substrates for the trace detection of melamine and rhodamine 6G is demonstrated, which shows limits of detection smaller than 0.1 ppm and analytical enhancement factors on the order of 104 as compared to bare aluminium foil.
ABSTRACT
Strategies for production and use of nanomaterials have rapidly moved towards safety and sustainability. Beyond these requirements, the novel routes must prove to be able to preserve and even improve the performance of the resulting nanomaterials. Increasing demand of high-performance nanomaterials is mostly related to electronic components, solar energy harvesting devices, pharmaceutical industries, biosensors, and photocatalysis. Among nanomaterials, Zinc oxide (ZnO) is of special interest, mainly due to its environmental compatibility and vast myriad of possibilities related to the tuning and the enhancement of ZnO properties. Doping plays a crucial role in this scenario. In this work we report and discuss the properties of undoped ZnO as well as lanthanide (Eu, Tb, and La)-doped ZnO nanoparticles obtained by using whey, a by-product of milk processing, as a chelating agent, without using citrate nor any other chelators. The route showed to be very effective and feasible for the affordable large-scale production of both pristine and doped ZnO nanoparticles in powder form.
