Two-dimensional (2D) transition metal dichalcogenides materials have recently been explored as possible substrates for surface-enhanced Raman spectroscopy (SERS). However, in comparison to the conventional noble-metal-based counterpart, most of the 2D materials have very small area for SERS measurement, which is a big limitation toward practical applications. Herein, we presented our study of SERS using substrate-scale continuous ReS 2 monolayer films on flexible mica substrate. We demonstrated that the charge transfer between the target molecules and the atomically thin ReS 2 can be modulated by the underlying substrate of ReS 2 , resulting in greatly different suppressing level of FL background. Kelvin probe force microscopy revealed a large difference of surface potential between ReS 2 /SiO 2 and ReS 2 /mica, suggesting that the strong FL quenching of molecular on ReS 2 /mica might be attributed to the inert surface of layered mica. The large-area ReS 2 monolayer films on mica show a detection limit of R6G molecule around 10 −7 M and a robust SERS performance after an exposure in air for one month and repeated bending for 1000 times. Our work explores the practical application of 2D ReS 2 for molecular detection via SERS technique.
The expected approach to improve the electrochemical performance of layered transition metal dichalcogenides is to thin them down to monolayer for minimizing the barrier of lithium-ion intercalation and diffusion. In this work, a distinct nanocomposite constructed from nanosized ReS 2 monolayers uniformly embedded in nitrogen-doped carbon nanotubes is synthesized via a facile hydrothermal method followed by calcination. When evaluated as anode materials for lithium ion batteries, the robust nanocomposites exhibit a reversible capacity of 825 mAh g −1 at 100 mA g −1 after 100 cycles with an initial Coulombic efficiency as high as 83%, and more importantly, retain an outstanding capacity of 612 mAh g −1 at 1 A g −1 after 500 cycles with an excellent capacity retention of 80%. Kinetics analysis of the redox reactions reveals that 86% of the charge storage is controlled by a capacitive behavior, leading to both high-rate and long-life lithium storage performances. The design of the nanocomposites offers a promising strategy to achieve extra power over batteries by capacitive energy storage.
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