Antimony sulfide (Sb_2S_3) is a semiconductor composed of quasi-one-dimensional ribbon-like structural units, which give rise to pronounced structural anisotropy in the bulk crystal. Despite growing interest in Sb_2S_3, in particular Sb_2S_3 thin films, a detailed understanding of its symmetry-based lattice dynamics remains incomplete. Here, we present a combined experimental and theoretical study of polarization-dependent Raman scattering in Sb_2S_3 thin films. We derive the Raman selection rules from the crystal symmetry and calculate the zone-center phonon modes and corresponding Raman tensors using density functional theory. The calculated polarization dependencies are systematically compared with polarization-dependent Raman measurements performed on oriented crystalline domains of Sb_2S_3 thin films. This combined analysis enables reliable mode assignments, elucidates the anisotropic Raman response associated with the ribbon-like crystal structure, and demonstrates the sensitivity of polarized Raman spectroscopy to crystal orientation and structural order in antimony chalcogenide (Sb_2S_3, Sb_2Se_3) as well as isostructural Bi_2S_3 thin films.

The spatially controlled covalent functionalization of graphene allows for local modulation of its electronic and chemical properties. However, existing approaches either offer high lateral precision without independent reaction tuning or provide energetic control at the expense of spatial confinement. Herein, we introduce a photoelectrochemical-driven strategy that combines the spatially resolved laser activation of precursors with electrochemical reaction gating that allows for modulation of the electron-transfer driving force. Within a defined potential window, the degree of covalent addend binding on graphene can be continuously tuned by varying the applied bias under otherwise identical irradiation conditions. The electrochemical potential serves as an independent control parameter, complementing laser power and irradiation time, and thus provides an additional tool for the calibration of the degree of functionalization. Negative potentials enhance the covalent addend binding, whereas positive potentials suppress the reaction. This allows for a reproducible switching between active and inactive states. The electrochemically defined "off" condition enables in situ Raman characterization in the presence of the precursor solution without inducing unintended additional addend binding, enabling uninterrupted, stepwise monitoring of the functionalization process. This combination of laser-pathway guided spatially resolved patterning and voltage-controlled reaction tuning establishes a dual-control platform for future precision graphene chemistry.

Connecting two-dimensional (2D) material layers via interface linkers represents a new avenue for fabricating 2D heterostructures. Utilizing light to remotely modulate this interface function allows for seamless assembly and patterning in a single run. Here, an efficient method for fabricating patterned 2D heterostructures using direct laser writing is demonstrated, drawing a conceptual parallel to laser printing. In the approach, functionalized transition metal dichalcogenide (TMD) dispersions serve as inks, graphene as the substrate, and a Raman laser as the patterning tool. Unlike laser printing's electrostatic interactions, the method achieves patterned assembly through covalent bonding between TMDs and graphene. Selective Raman laser irradiation of functionalized TMD/graphene heterostructures triggers localized reactions, forming chemically modified domains exclusively in the laser-irradiated regions, as confirmed by Raman spectroscopy, Kelvin probe force microscopy (KPFM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Experimental and theoretical analyses of the interface composition and structure provide new insights into laser-induced chemistry. The work demonstrates the potential for high-throughput assembly of customizable 2D heterostructures, with enhanced compatibility for subsequent patterning through photolabile linkers and photoinduced coupling. Additionally, the results provide deeper insights into chemistry within confined 2D spaces, offering a novel approach to nanoscale heterostructure engineering.

We herein present a significant advance in the understanding of the reaction mechanisms and the influence of the laser "writing" parameters in the laser-triggered activation of dibenzoyl peroxides (DBPO) and the subsequent high-precision covalent patterning of functional groups on monolayer graphene. Our straightforward and versatile procedure allows a complete deconvolution of the laser-induced functional group grafting in the "writing" step from a competing functionalization in the corresponding Raman characterization by a full removal of the DBPO film after covalent group attachment. This allows an in-depth analysis and understanding of the underlying laser "writing" and "reading" parameters-laser power and irradiation time-and thus a precise control of the degree of functionalization. Furthermore, by optimizing these parameters, the lateral dimension limits of the individual graphene patterned structures can be scaled down to 1.5 mu m, with the potential to further improve the pattern size to the nanoscale in combination with a lithographically etched mask approach.

We present a novel approach to achieve spatial variations in the degree of non-covalent functionalization of twisted bilayer graphene (tBLG). The tBLG with twist angles varying between ~5° and 7° was non-covalently functionalized with 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) molecules. Our results show a correlation between the degree of functionalization and the twist angle of tBLG. This correlation was determined through Raman spectroscopy, where areas with larger twist angles exhibited a lower HATCN peak intensity compared to areas with smaller twist angles. We suggest that the HATCN adsorption follows the moiré pattern of tBLG by avoiding AA-stacked areas and attach predominantly to areas with a local AB-stacking order of tBLG, forming an overall ABA-stacking configuration. This is supported by density functional theory (DFT) calculations. Our work highlights the role of the moiré lattice in controlling the non-covalent functionalization of tBLG. Our approach can be generalized for designing nanoscale patterns on two-dimensional (2D) materials using moiré structures as a template. This could facilitate the fabrication of nanoscale devices with locally controlled varying chemical functionality.

Antimony shows promise as a 2D mono‐elemental crystal, referred to as antimonene. When exposed to ambient conditions, antimonene layers react with oxygen, forming new crystal structures, leading to significant changes in electronic properties. These changes are influenced by the degree of oxidation. Utilizing density‐functional theory calculations, stable configurations of bilayer antimony oxide and their corresponding electronic properties are studied. Additionally, different stacking arrangements and their effects on the physical properties of the materials are investigated. Furthermore, the analysis encompasses strain‐free heterobilayers containing both pristine and oxidized antimonene layers, aiming to understand the interplay between these materials and their collective impact on the bilayer properties. In the results, insight is provided into how the properties of antimony‐based bilayer structures can be modified by adjusting stoichiometry and stacking configurations.

Liquid phase exfoliation (LPE) has been used for the successful fabrication of nanosheets from a large number of van der Waals materials. While this allows to study fundamental changes of material properties' associated with reduced dimensions, it also changes the chemistry of many materials due to a significant increase of the effective surface area, often accompanied with enhanced reactivity and accelerated oxidation. To prevent material decomposition, LPE and processing in inert atmosphere have been developed, which enables the preparation of pristine nanomaterials, and to systematically study compositional changes over time for different storage conditions. Here, we demonstrate the inert exfoliation of the oxidation-sensitive van der Waals crystal, CrTe3. The pristine nanomaterial was purified and size-selected by centrifugation, nanosheet dimensions in the fractions quantified by atomic force microscopy and studied by Raman, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX) and photo spectroscopic measurements. We find a dependence of the relative intensities of the CrTe3 Raman modes on the propagation direction of the incident light, which prevents a correlation of the Raman spectral profile to the nanosheet dimensions. XPS and EDX reveal that the contribution of surface oxides to the spectra is reduced after exfoliation compared to the bulk material. Further, the decomposition mechanism of the nanosheets was studied by time-dependent extinction measurements after water titration experiments to initially dry solvents, which suggest that water plays a significant role in the material decomposition.

Covalent functionalization of two-dimensional molybdenum disulfide (2D MoS2 ) holds great promise in developing robust organic-MoS2 hybrid structures. Herein, for the first time, we demonstrate an approach to building up a bisfunctionalized MoS2 hybrid structure through successively reacting activated MoS2 with alkyl iodide and aryl diazonium salts. This approach can be utilized to modify both colloidal and substrate supported MoS2 nanosheets. We have discovered that compared to the adducts formed through the reactions of MoS2 with diazonium salts, those formed through the reactions of MoS2 with alkyl iodides display higher reactivity towards further reactions with electrophiles. We are convinced that our systematic study on the formation and reactivity of covalently functionalized MoS2 hybrids will provide some practical guidance on multi-angle tailoring of the properties of 2D MoS2 for various potential applications.

Antimonene, a monolayer of β-antimony, is increasingly attracting considerable attention, more than that of other monoelemental two-dimensional materials, due to its intriguing physical and chemical properties. Under ambient conditions, antimonene exhibits a high thermodynamic stability and good structural integrity. Some theoretical calculations predicted that antimonene would have a high oxidation tendency. However, it remains poorly investigated from the experimental point of view. In this work, we study the oxidation behavior of antimonene nanosheets (ANS) prepared by ultrasonication-assisted liquid-phase exfoliation. Using a set of forefront analytical techniques, a clear effect of sonication time on the surface chemistry of prepared ANS is found. A dynamic oxidation behavior has been observed, which upon annealing at moderate temperature (210 °C) resulted in a semiconducting behavior with a bandgap of approximately 1 eV measured by ultraviolet photoelectron spectroscopy. This study yields valuable information for future applications of antimonene and paves the way towards novel modification approaches in order to tailor its properties and complement its limitations.

Two-dimensional (2D) antimony, so-called antimonene, can form antimonene oxide when exposed to air. We present different types of single- and few-layer antimony oxide structures, based on density functional theory (DFT) calculations. Depending on stoichiometry and bonding type, these novel 2D layers have different structural stability and electronic properties, ranging from topological insulators to semiconductors with direct and indirect band gaps between 2.0 and 4.9 eV. We discuss their vibrational properties and Raman spectra for experimental identification of the predicted structures.