Surface-enhanced Raman scattering (SERS) as a label-free, non-contact, highly sensitive, and powerful technique has been widely applied in determining bio- and chemical molecules with fingerprint recognitions. 2-dimensional (2D) materials with layered structures, tunable optical properties, good chemical/physical stabilities, and strong charge–transfer interaction with molecules have attracted researchers’ interests. Two-D materials with a large and flat surface area, as well as good biocompatibility have been considered promising candidates in SERS and widely applied in chemical and bio-applications. It is well known that the noble metallic nanostructures with localized surface plasmon effects dominate the SERS performance. The combination of noble metallic nanostructure with 2D materials is becoming a new and attractive research domain. Until now, the SERS substrates combined with 2D materials, such as 2D graphene/metallic NPs, 2D materials@metallic core-shell structures, and metallic structure/2D materials/metallic structure are intensely studied. In this review, we introduce different kinds of fabrication strategies of 2D and 3D SERS substrates combing with 2D materials as well as their applications. We hope this review will help readers to figure out new ideas in designing and fabricating SERS substrates with high SERS performance that could enlarge the applicable domains of SERS.
Traditional graphite anode material typically shows a low theoretical capacity and easy lithium decomposition. Molybdenum disulfide is one of the promising anode materials for advanced lithium-ion batteries, which possess low cost, unique two-dimensional layered structure, and high theoretical capacity. However, the low reversible capacity and the cycling-capacity retention rate induced by its poor conductivity and volume expansion during cycling blocks further application. In this paper, a collaborative control strategy of monodisperse MoS2/graphite composites was utilized and studied in detail. MoS2/graphite nanocomposites with different ratios (MoS2:graphite = 20%:80%, 40%:60%, 60%:40%, and 80%:20%) were prepared by mechanical ball-milling and low-temperature annealing. The graphite sheets were uniformly dispersed between the MoS2 sheets by the ball-milling process, which effectively reduced the agglomeration of MoS2 and simultaneously improved the electrical conductivity of the composite. It was found that the capacity of MoS2/graphite composites kept increasing along with the increasing percentage of MoS2 and possessed the highest initial discharge capacity (832.70 mAh/g) when MoS2:graphite = 80%:20%. This facile strategy is easy to implement, is low-cost, and is cosmically produced, which is suitable for the development and manufacture of advance lithium-ion batteries.
17 February 2025 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Quick and highly sensitive detection of the SARS-CoV-2 virus can efficiently reduce the possibility of viral spreading. In this study, a differential-phase surface plasmon resonance (SPR) biosensor is constructed to directly detect the SARS-CoV-2 virus. The SARS-CoV-2 spike protein antibodies are applied as bioprobes and functionalized on Au film, forming a sensing surface. A numerical analysis of the phase shifts of the SPR interferogram, termed the index of phase shifts (IoPS), is presented, which does not depend on a reference beam or an s-component beam. The IoPS can sensitively reflect small changes in the refractive index (as low as 3.75 × 10−10 RIU) when NaCl solution is used as an analyte. The limit of detection (LOD) of the proposed SPR biosensor in detecting the SARS-CoV-2 S protein is 1 ag mL−1. In comparison with a SARS-CoV-2 negative control (NC) sample collected from healthy people, which has an IoPS of ΔϕNC = 39°, the SPR biosensor shows a very strong response to the SARS-CoV-2 virus collected from infected people with a phase shift of ΔϕIoPS = 566°. To further improve the detection sensitivity, a sandwich structure is designed by applying SARS-CoV-2 spike protein antibody functionalized gold nanoparticles (anti-S@AuNPs). This reduces the LOD for the detection of the SARS-CoV-2 S protein to 0.1 ag mL−1.
Heavy metal contamination poses significant environmental risks to groundwater and soil, necessitating efficient early-warning technologies for leakage detection. This study proposes a novel early-warning approach for heavy metal leakage using the self-potential (SP) method. A coupled numerical model integrating seepage, ion diffusion, and electric potential fields was developed within the COMSOL Multiphysics platform in order to elucidate the dynamic response mechanism of SP signals to advancing seepage fronts. Key findings reveal that the SP signal responds 1.5 h earlier than the contaminant diffusion front (Case 1), providing a critical early-warning window. The leakage process exhibits a distinct bipolar SP anomaly pattern (negative upstream/positive downstream), with the most significant response observed at the downstream toe area. Consequently, an optimized monitoring strategy prioritizing downstream deployment is proposed and validated using a representative landfill model. This SP-based technology offers a promising solution for real-time environmental risk monitoring, particularly in ecologically sensitive zones.
Slope landslide risk presents a critical challenge throughout high-speed railway construction and operation. Precise detection of sliding surfaces is essential for disaster prevention. This study develops an electrical detection method using complex electrode arrays, specifically addressing high-speed railway slope exploration constraints including confined spaces, significant investigation depths, and complex terrain. Numerical simulations analyzed the electric field distribution characteristics of power supply electrodes under various spatial constraints (half-space and full-space), revealing resolution differences between power supply combinations for target areas. Further comparative numerical modeling demonstrated that complex electrode arrays significantly enhance imaging quality over simple arrays in complex terrain. Finally, field validation confirmed the high reliability of complex observation systems for detecting slip surfaces along high-speed railway slopes. Therefore, under complex terrain conditions, utilizing complex observation systems to acquire multi-dimensional spatial data, integrated with topography-incorporated inversion technology, enables precise slip surface detection. This approach provides a reliable method for geological hazard mitigation in high-speed railway operations.