Sulfur doped MoO2 hollow nanospheres as a highly sensitive SERS substrate for multiple detections of organic pollutants

Au nanoparticles decorated β-Bi2O3 as highly-sensitive SERS substrate for detection of methylene blue and methyl orange

In this work, Au/Bi2O3 was synthesized by loading Au nanoparticles (NPs) onto β-Bi2O3 by a simple solution reduction method. β-Bi2O3 was synthesized by a precipitation-thermal decomposition procedure, which results in significantly improved SERS detection limits down to 10-9 M for methylene blue (MB) and 10-7 M for methyl orange (MO) as probe molecules, comparable to those reported for the best semiconductor SERS substrates. In particular, further deposition of Au NPs (5.20% wt%) onto β-Bi2O3 results in a two-order-of-magnitude enhancement in detection sensitivity, achieving a detection limit of 10-11 M for MB and 10-9 M for MO. Under ultraviolet/visible irradiation, the Au/Bi2O3 hybrids substrate exhibits superior self-cleaning ability due to its photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. The advanced composite substrate simultaneously achieved ultra-low mass loading of Au NPs, outstanding detection performance, good reproducibility, high stability and self-cleaning ability. The development strategy of low load noble metal coupled high performance semiconductor β-Bi2O3 to obtain nano-hybrid materials provides a method to balance SERS sensitivity, cost effectiveness and operational stability, and can be synthesized in large quantities, which is a key step towards commercialization and has good reliability prospects.

Facet-Dependent SERS Activity of Co3O4

Surface-enhanced Raman spectroscopy (SERS) is an ultra-sensitive and rapid technique that is able to significantly enhance the Raman signals of analytes absorbed on functional substrates by orders of magnitude. Recently, semiconductor-based SERS substrates have shown rapid progress due to their great cost-effectiveness, stability and biocompatibility. In this work, three types of faceted Co₃O₄ microcrystals with dominantly exposed {100} facets, {111} facets and co-exposed {100}-{111} facets (denoted as C-100, C-111 and C-both, respectively) are utilized as SERS substrates to detect the rhodamine 6G (R6G) molecule and nucleic acids (adenine and cytosine). C-100 exhibited the highest SERS sensitivity among these samples, and the lowest detection limits (LODs) to R6G and adenine can reach 10^-7 M. First-principles density functional theory (DFT) simulations further unveiled a stronger photoinduced charge transfer (PICT) in C-100 than in C-111. This work provides new insights into the facet-dependent SERS for semiconductor materials.

Tailored FTO/Ag/ZIF-8 structure as SERS substrate for ultrasensitive detection

In this work, a series of F-doped SnO₂/Ag/zeolite imidazole framework (FTO/Ag/ZIF-8) sandwich structure have been successfully fabricated via a magnetic sputtering method and serve as surface-enhanced Raman scattering (SERS) substrate. The magnetic sputtering time of Ag was adjusted to obtain the optimal SERS substrate. The commonly used 4-mercaptobenzoic acid (4-MBA) molecules was selected for the SERS experiment. When the sputtering time of Ag nanoparticles (NPs) was 120 s, the FTO/Ag/ZIF-8 substrate showed the maximum SERS performance. In the system, the electromagnetic mechanism (EM) and charge-transfer (CT) enhancement mechanism have synergistic effect on the SERS phenomenon. Ag NPs was used to generate electromagnetic hot spots, which was beneficial to the EM mechanism. ZIF-8 could adsorb and capture more 4-MBA probe molecules to the hotspots. At the same time, CT happened between Ag, ZIF-8, and 4-MBA probe molecules, which was attribute to the CM mechanism. The enhancement factor (EF) of the composite SERS substrate was as high as 7.67 × 10⁶. The detection limit of the substrate can reach 10^-9 M of 4-MBA probe molecules. Moreover, the SERS templates showed good stability, the SERS signals almost unchanged after naturally kept for 6 months. Besides, due to the high sensitivity and good stability of the substrates, this work might broaden the potential practical application of SERS.

Applications of surface-enhanced Raman spectroscopy in environmental detection

As the human population grows, the anthropogenic impacts from various agricultural and industrial processes produce unwanted contaminants in the environment. The accurate, sensitive and rapid detection of such contaminants is vital for human health and safety. Surface-enhanced Raman spectroscopy (SERS) is a valuable analytical tool with wide applications in environmental contaminant monitoring. The aim of this review is to summarize recent advancements within SERS research as it applies to environmental detection, with a focus on research published or accessible from January 2021 through December 2021 including early-access publications. Our goal is to provide a wide breadth of information that can be used to provide background knowledge of the field, as well as inform and encourage further development of SERS techniques in protecting environmental quality and safety. Specifically, we highlight the characteristics of effective SERS nanosubstrates, and explore methods for the SERS detection of inorganic, organic, and biological contaminants including heavy metals, pharmaceuticals, plastic particles, synthetic dyes, pesticides, viruses, bacteria and mycotoxins. We also discuss the current limitations of SERS technologies in environmental detection and propose several avenues for future investigation. We encourage researchers to fill in the identified gaps so that SERS can be implemented in a real-world environment more effectively and efficiently, ultimately providing reliable and timely data to help and make science-based strategies and policies to protect environmental safety and public health.