Molybdenum disulfide (MoS₂), a promising two-dimensional transition-metal dichalcogenide, presents a challenge in the tuning of its optoelectronic and chemical properties. Herein, we demonstrate an efficient route to alter the crystalline structure of MoS₂ by chemical exfoliation. Using NaK metal alloys, exfoliated and covalently functionalized MoS₂ derivatives were obtained with a high metallic (1T) phase ratio, up to 94.5%. Consequently, exfoliated MoS₂ showed a significant surface-enhanced Raman scattering activity toward rhodamine 6G (R6G) and crystal violet, with low detection limits. The versatility of this approach allows the covalent functionalization of MoS₂ without relying on edge or basal-plane defects of the structure and preserving the high-ratio 1T phase.

During the last 15 years, 2D materials have revolutionized the field of materials science. Moreover, because of their highest surface‐to‐volume ratio and properties extremely susceptible to their interaction with the local environment they became powerful active components for the development the high‐performance chemical sensors. By combining different 2D materials to form van der Waals heterostructures (VDWHs) it is possible to overcome the drawback of individual materials (such as inertness and zero‐bandgap of pristine graphene and less environmental stability of transition metal dichalcogenides). Meanwhile, VDWHs possess unprecedented and fascinating properties arising from the intimate interaction between the components, which can yield superior sensitivities, higher selectivity, and stability when employed to detect gases, biomolecules, and other organic/inorganic molecules. Herein, the latest developments and advances in the field of chemical sensors based on VDWH of 2D materials, with specific insight into the sensing mechanisms, are reviewed and future directions, challenges, and opportunities for the development of the next generation of (bio)chemical sensors with potential impact in environmental sciences and biomedical applications, and more specifically in (bio)chemical defense, industrial safety, food, and environmental surveillance, and medical (early) diagnostics, are discussed.

Graphene-based materials are particularly suitable platforms for the development of new systems able to release drugs upon the application of controlled electrochemical stimuli.

The reactivity of reduced graphene sheets (graphenide), obtained by dissolution of graphite intercalation compounds, in particular KC8, was systemically studied by covalent functionalization with 4-fluorobenzenediazonium tetrafluoroborate and 4-iodoaniline in different solvents (5 pure and 7 solvents with addition of K+ chelating agents). Interestingly, proper solvation of the potassium cations was beneficial to the covalent functionalization, while excessive solvation led to destabilization and flocculation, with decreased reactivity of graphenide. The results were confirmed by scanning Raman spectroscopy (SRS) and X-ray photoelectron spectroscopy (XPS).

2D transition metal dichalcogenide materials have attracted increasing attention as active surface‐enhanced Raman spectroscopy (SERS) platforms. In this study, the influence of n‐ and p‐type doping of exfoliated MoS₂ (exMoS₂) hybrids on the SERS performance is investigated, employing Rhodamine 6G (R6G) as a probe molecule. It is demonstrated that n‐doped exMoS₂ hybrids (exMoS₂ mixed with C₆₀, graphene, and sodium dodecyl sulfate) exhibit enhanced SERS intensities, while p‐doping (exMoS₂ mixed with TCNQ) resulted in inhibited SERS enhancement. A key discovery is the linear relationship between Raman enhancement of MoS₂/dopant hybrids and the difference in their LUMO energy levels, which dictate the degree and direction of charge transfer. Interestingly, MC₆₀‐4, a C₆₀‐doped hybrid, deviates from the linear relationship, displaying remarkable SERS enhancement owing to its chemical interaction and unique Raman scattering activity. The findings provide critical insights into the SERS enhancement behavior of doped MoS₂, facilitating precise tuning of SERS intensities by manipulating the MoS₂ doping state.