Understanding how nanoparticle geometry and dimensionality govern interactions with lipid membranes is critical for the rational design of safe materials for biomedical applications. In this context, this work aims to evaluate the effects of polyethylene glycol-stabilized gold nanorods (PEG-AuNRs) and graphene oxide nanosheets (PEG-GONSs) on biomimetic membranes composed of pure dipalmitoylphosphatidylcholine (DPPC) and a DPPC–archaeal lipid mixture (97:3 mol%). Although both nanoparticles exhibited favorable membrane compatibility at low concentrations, the extended two-dimensional geometry and high surface contact area of graphene oxide nanosheets promoted comparatively stronger interfacial interactions than the rod-shaped gold nanoparticles. These findings highlight the critical importance of nanoparticle shape and dimensionality in modulating nano-bio interfaces and guiding the rational design of geometry-tailored and clinically translatable nanomaterials for biomedical applications, including drug delivery and cancer nanotheranostics.

The present study focuses on liquid-precursor-mediated chemical vapor deposition (under ambient pressure and moderate temperature range) of WSe2 on sapphire using ammonium meta-tungstate and sodium cholate. The investigation provides additional results and information for the WSe2 cluster formations on sapphire as an extension of our previous study, especially based on structural, chemical and morphological characterization of the observed largest and predominant polygonal WSe2 domains whose lateral size can reach several hundreds of micrometers. In addition, highly symmetrical shapes were also observed. The Raman spectroscopy and atomic force microscopy identified the formation of both mono- and multilayered WSe2. Moreover, the Raman spectrum analysis shows a complex peak structure with unusual splitting effects in the second-order modes marking strong activity of excitonic-resonance processes.

Tungsten disulfide (WS2) is a member of the transition metal dichalcogenide family with a layer-number-dependent bandgap and numerous potential applications in optics and optoelectronics; however, the controlled growth process is still challenging. Herein, we report the synthesis details of single- and few-layer WS2 via sulfurization of WO3 films, using sodium sulfide (Na2S)-assisted substrate pretreatment. Na2S plays a role as a source of H2S, providing a low-cost efficient and eco-friendly growth method. A combination of x-ray diffraction (XRD) analysis, atomic force microscopy, and Raman spectroscopy confirms that the obtained WS2 samples indeed consist of a single S-W-S layer. WS2 demonstrated strong visible-wavelength photoluminescence at room temperature. In addition, we demonstrate a polarization-plane rotation when linearly polarized light propagates through the WS2 nanolayer, which opens many possibilities for ultrathin optics applications.

This work presents a comparative analysis of the results of silicon carbide synthesis through the carbonization of Si (001) and Si (111) substrates in the temperature range 1130–1140 °C. The synthesis involved chemical vapor deposition utilizing thermally stimulated methane reduction in a hydrogen gas stream. The experiments employed an Oxford Nanofab Plasmalab System 100 apparatus on substrates from which the native oxide was removed according to established protocols. To minimize random experimental variations (e.g., deviations from set parameters), short synthesis durations of 3 and 5 min were analyzed. The resultant thin films underwent evaluations through several techniques, including X-ray photoelectron spectroscopy, X-ray diffractometry, optical emission spectroscopy with glow discharge, and transmission electron microscopy. A comparison and analysis were conducted between the results from both substrate orientations.

We present the results of silicon carbide (SiC) thin film synthesis on Si(111) substrates using chemical vapor deposition by decomposing CH4 in H2 at 1135 °C. The experiments were conducted in an Oxford Nanofab Plasmalab System 100 for carbon phase deposition times of 3, 5, 20, 60, and 90 min on Si(111) with or without native oxide, following established protocols. Our studies show that either predominantly crystalline SiC or a mixture of SiC and Si–O/Si–O–C glass forms on Si substrates significantly doped with carbon and oxygen, depending on the presence or absence of native oxide. The thickness of the SiC film ranges from approximately 5–6 nm for films synthesized in 3 min to over 15 nm for those synthesized in 90 min, while the size of the crystal grains varies from a few to 110 nm depending on the synthesis duration. The findings suggest that the complex composition of the thin films and the region beneath them can more effectively compensate for the differences in lattice parameters and thermal expansion coefficients between the SiC film and the Si substrate; thus, this method is promising for depositing intermediate thin films of SiC on Si substrates.

The synthesis of high-quality two-dimensional molybdenum disulfide (MoS 2 ) is a crucial step for achieving novel applications in nanoelectronics and optoelectronics. This study introduces a novel c-cut sapphire pre-treatment strategy using sodium sulfide (Na 2 S) to enhance MoS 2 growth. In this method, the substrate is dipped in a 2 × 10 −2 M deionized water solution of Na 2 S, which facilitates the release of hydrogen sulfide (H 2 S) through a reaction with atmospheric moisture. The H 2 S generated in situ acts as an effective catalyst for the growth of MoS 2 monolayers, offering a viable alternative to the conventional Ar/H 2 gas mixture used in many synthesis protocols. This approach significantly improves the quality, uniformity, and growth rate of MoS 2 layers, as confirmed by XPS, AFM, and Raman analysis, and simplifies the synthesis process by eliminating the need for complex gas flow systems. The results demonstrate that this Na 2 S pretreatment method is both cost-effective and scalable, presenting a promising solution for the efficient and sustainable production of MoS 2 for future technological applications.

We report a two-step growth process of MoS2 nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS2 layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS2 flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS2 nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS2, whereas transmission electron microscopy analysis revealed triangular MoS2 nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS2. Raman data revealed the typical modes of high-quality MoS2 nanoflakes. Finally, we presented the photocurrent dependence of a MoS2-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current–voltage dependence across various luminous flux outlined the sensitivity of MoS2 to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity.

Abstract The results of a successful synthesis of a WSe2/PtSe2 heterostructures are presented. High quality crystalline films were achieved through a one–step selenization of a pre-deposited tungsten film with pre-deposited platinum as an underlayer. The role of the PtSe2 layer, formed during selenization, was to assists the growth of crystalline WSe2. The existence of WSe2 was confirmed using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The crystallinity of the samples was investigated using X-ray diffraction (XRD). Surface measurements were performed using atomic force microscopy (AFM).

In this work, we present the results of measurements of the Raman spectrum of the root 3x root 3R30 degrees reconstruction of graphene grown on 4H-SiC(0001), the so-called buffer layer. The extracted Raman spectrum of the buffer layer shows bands, different from those of graphene, which can be attributed to the interaction of the buffer layer with the SiC substrate. In particular, in the high-wavenumber region, at least three bands are observed in the wavenumber regions 1,350-1,420, 1,470-1,490 and 1,520-1,570 cm-1. The assignment of the buffer layer bands is supported here by tight-binding simulations of the one-phonon density of states for structures with a sufficiently large number of Si-C bilayers for reaching convergence. The converged phonon density of states is found to be in semi-quantitative agreement with the latter two bands, and therefore, the tight-binding predictions of the lattice dynamics of the structure can be used for their assignment to buffer layer vibrations. Namely, the Raman band at about 1,550 cm-1 can be assigned to modified in-plane optical phonon branches of graphene, while the Raman band at about 1,490 cm-1 can be assigned to modified folded parts of these branches inside the Brillouin zone of the buffer layer and can be considered as a Raman fingerprint of the buffer layer. We present the results of measurements of the Raman spectrum of the root 3x root 3R30 degrees reconstruction of graphene grown on 4H-SiC(0001), the so-called buffer layer (BL) in the wavenumber region 1,200-1,650 cm-1. The assignment of the BL bands is supported by tight-binding simulations of the one-phonon density of states (DOS) for structures with a sufficiently large number of Si-C bilayers for reaching convergence. The converged phonon DOS is found to be in semi-quantitative agreement with the experimental Raman spectra.image

Bulk single crystals of WTe2 were grown by the self-flux method and characterized by X-ray diffraction, polarized micro-Raman spectroscopy, and optical microscopy. All methods revealed a high crystalline quality, thus demonstrating the advantages of the growth method used as a starting base for the synthesis of high-quality 2D materials. In each main scattering configuration, we recorded a series of Raman spectra in different sample orientations achieved by rotating the sample around the incident laser beam. In addition to the well-established case of excitation along the c crystal axis, we also applied laser excitation along the a and b axes. Thus, scattering configurations were also realized in the XZ and YZ polarization planes, for which no comparative literature data have yet been established. In these experiments, two new Raman-active phonons with B2 symmetry and frequencies of 89 cm−1 and 122 cm−1 were identified. The obtained experimental data enabled us to derive the magnitude ratios of all three tensor elements of the A1 modes and to find their phase differences.

Abstract In this work, we present a study on the epitaxial growth of MoS2 on both sapphire and mica substrates using the Chemical Vapor Deposition (CVD) method. The research focuses on optimizing the growth conditions in order to achieve reproducible results and explore the potential of conventional and Van der Waals epitaxy for synthesizing nanolayers and nanoclusters of transition metal dichalcogenides. By carefully selecting appropriately oriented substrates and performing targeted surface modification, we successfully achieved the desired epitaxial growth. The properties of the obtained structures are thoroughly investigated, with emphasis on their potential applications. This research contributes to the development of scalable and high-quality Transition Metal Dichalcogenide (TMD) growth technique, opening prospects for practical applications in various fields.

Palladium diselenide (PdSe2) is an important transition metal dichalcogenide with a layers-dependent bandgap and many potential applications in electronic and optoelectronic devices. However, the availability of high-quality large-area crystals with phase control is still challenging. Herein, we report the successful growth of large-area PdSe2 single crystals using the self-flux method. The crystal structure, quality, and elemental composition were characterized by X-ray Diffraction, Energy-Dispersive X-ray Spectroscopy, and High-Resolution Transmission Electron Microscopy (HR TEM). The Raman-active vibrational modes of PdSe2 were identified using polarized Raman spectroscopy. The controlled synthesis of PdSe2 enables the potential for a broad range of heterostructures and further integrated optical and electro-optical applications.

PtSe2 has asserted its key role among the emerging 2D transition metal dichalcogenides, however, its simplified growth process with controlled number of layers, high crystalline quality, and on inexpensive substrates is still challenging. Here, we report the synthesis details of PtSe2 layers on soda lime glass substrates by selenization of predeposited Pt layers using the thermally assisted conversion method at atmospheric pressure. PtSe2 syntheses are confirmed by X-ray photoelectron spectroscopy and Raman analysis. The layers were further investigated with transmission electron microscopy and optical ellipsometry, revealing the thickness and its dependence on the metal precursor sputtering time. Finally, the integration of PtSe2 as transparent conductive layers in polymer-dispersed liquid crystal structures operating as near-infrared light shutters is demonstrated and device performance is discussed. The proposed simple and inexpensive synthesis approach opens up new directions toward PtSe2 potential technological applications, including ITO-free optoelectronics.

The deposition of thin uniform dielectric layers on graphene is important for its successful integration into electronic devices. We report on the atomic layer deposition (ALD) of Al2O3 nanofilms onto graphene grown by chemical vapor deposition onto copper foil. A pretreatment with deionized water (DI H2O) for graphene functionalization was carried out, and, subsequently, trimethylaluminum and DI H2O were used as precursors for the Al2O3 deposition process. The proper temperature regime for this process was adjusted by means of the ALD temperature window for Al2O3 deposition onto a Si substrate. The obtained Al2O3/graphene heterostructures were characterized by Raman and X-ray photoelectron spectroscopy, ellipsometry and atomic force and scanning electron microscopy. Samples of these heterostructures were transferred onto glass substrates by standard methods, with the Al2O3 coating serving as a protective layer during the transfer. Raman monitoring at every stage of the sample preparation and after the transfer enabled us to characterize the influence of the Al2O3 coating on the graphene film.

Owing to their exceptional properties, which are usually determined by the growth conditions, 2D transition metal dichalcogenides (TMDCs) offer numerous research directions for applications in the fields of spintronics, valleytronics, and optoelectronics. Here, we focus on the chemical vapor deposition (CVD) synthesis of WSe2 (tungsten diselenide) nanoclusters/nanoflakes by using a liquid precursor for tungsten (ammonium metatungstate) on Si/SiO2, fused silica, and sapphire substrates. Various WSe2 clusters with different sizes, thicknesses, and geometries were analyzed by means of optical and atomic force microscopy (AFM) and Raman spectroscopy. The observed structures were mostly WSe2 multilayers; however, monolayer formations were also found. They showed significant morphological differences, as well as wide nucleation density and size variations, possibly related to precursor/substrate surface interactions under the same CVD synthesis conditions. The largest WSe2 domains with a lateral size of up to hundreds of micrometers were observed on sapphire, probably caused by a higher growth rate of singular nucleation sites. WSe2 domains with irregular and triangular shapes were simultaneously identified on fused silica, whereas multilayered pyramidal WSe2 structures dominated in the case of Si/SiO2 substrates. The application of polarized Raman spectroscopy to precisely determine and differentiate the characteristic vibrational modes (A1g, E2g, and 2LA(M)) enabled the unambiguous identification of 2D and/or multilayered WSe2 formations with a high crystallinity level. The presented comparative analysis of samples prepared in relatively simple synthesis conditions (moderate working temperatures and ambient pressure) provides a base for further progress of the facile metatungstate CVD method and relevant opportunities for the exploration of 2D TMDC materials.

We report on the concentration dependence of the dispersion of single walled carbon nanotubes, SWCNTs, in a nanocomposite with a recently synthesized ferroelectric and optically active thermotropic liquid crystal ((R,E)-4-(4-((3,7-dimethyloctyl) oxy) styryl) phenyl 4-(undecyloxy)benzoate. Excellent dispersion of the SWCNTs in the concentration range from 0.01 up to 10 wt % was proven by means of differential scanning calorimetry, polarized optical microscopy, and Raman spectroscopy. It is believed to be facilitated by the formation of core-shell fibres, consisting of liquid crystal decorated SWCNTs, yet in the solution state. The fibres are maintained after the solvent evaporation and so the aggregation at elevated temperatures is prevented. The preservation of the liquid crystalline behaviour in all investigated cases can be considered as an additional benefit.

A nanocomposite built of the hydrogen-bonded (HB) dimer liquid crystal 4-heptyloxybenzoic acid (7OBA) and Graphene oxide (GO) exhibiting a cascade of phase transitions and phases not typical for pristine 7OBA, was investigated by optical polarization microtexture analysis and Raman spectroscopy. We use the 7OBA/GO nanocomposite beacause of the effective functionalizing properties of GO to study the generation and development of the ferroelectric smectic C G phase in its bi-tilted configuration. For the appearance of the C G phase with its substructures we propose an explanation based on the HB formation between 7OBA dimers in closed and open conformations and the GO sheets, aided by the π–π interaction with graphene hexagons which are free from functional groups. We propose molecular and macroscopic models for the substructures C Gcl and C Gln and indicate their triclinic C 1 symmetry, characterized by a polar vector directed oblique to the layers. This confirms that the bi-tilted C G and its substructures are ferroelectric in the bulk similarly to solid ferroelectrics, thus showing potential as material for controllable photonic functional devices.

PtSe2, an emerging two-dimensional (2D) transition metal dichalcogenide (TMD), has been considered as excellent electrochemical material however its photocatalytic properties are still unexplored. In the present work, antibacterial activity of few-layer PtSe2 coatings on glass substrate against Escherichia coli in dark and light irradiation conditions is reported. 2D PtSe2 layers were synthesized by selenization of pre-deposited Pt films using thermally assisted conversion (TAC) method. PtSe2 coatings with three different thicknesses were prepared by varying the Pt deposition time (Pt 3s, Pt 8s and Pt 10s), afterwards estimated by ellipsometric measurements to 7 nm, 9 nm and 12 nm, respectively. The X-Ray diffraction (XRD) patterns showed the diffraction peaks characteristic for PtSe2 with improving crystallinity when increasing the Pt deposition time. Similar tendency of increasing roughness was detected by measuring the surface topology using atomic force microscopy (AFM). The Raman spectra revealed typical PtSe2 modes, while a decrease of Se/Pt ratio and a transition from p-doped to n -doped PtSe2 for longer Pt deposition times was found by X-ray photoelectron spectroscopy (XPS) analysis. Ex-amination of the PtSe2 band gap by spectroscopic ellipsometry showed a decrease from 0.77 to 0.64 eV upon increase of the Pt deposition time, well correlated with the UV-VIS transmitted spectra. Formation of reactive oxygen species (ROS), mainly hydroxyl radicals (center dot OH) on the PtSe2 surface under light irradiation was demon-strated by EPR analysis. The antibacterial activity of PtSe2 coatings was investigated applying ISO standard procedure for semiconducting photocatalytic materials: (i) in dark, the antibacterial activity increased with the increase of Pt deposition time and the viability of the bacteria was reduced to 30% (Pt 3s) and 15% (Pt 10s) after treatment for 6 h. The effect was attributed to the increasing film thickness, roughness and surface coverage which facilitate the mechanical destruction of the bacteria cell; (ii) under light irradiation, the activity of PtSe2 (Pt 3s) was similar to that in dark showing low sensitivity to light. On the contrary, the PtSe2 (Pt 8s) and (Pt 10s) appeared very effective under light, with the bacteria viability after 6 h being only 7.3% and 1.2%, respectively. The observed photo-induced antibacterial activity was related to the synergy of several parameters, i.e. high crystallinity, semiconductor behavior and chemical composition. The present work opens the way for further investigation of PtSe2 as photoactive antibacterial material, the mechanism of its antibacterial activity and the possibility for application as antibacterial coating on transparent low-cost substrates.

Recently, low-dimensional structures in the form of bulk crystals and nanoflakes have received considerable interest due to their 2D unique functionality and promising applications in electronics, photonics, sensing devices and photovoltaic solar cells. As a result, remarkable efforts and modifications have been made for the synthesis process of crystalline material by the vapor transport technique. Here, an alternative concept of NbSe2 crystal growth by the chemical vapor transport (CVT) technique using bromine as a vapor transport agent is presented and subsequently analyzed by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) spectroscopy. X-ray powder diffraction analysis revealed hexagonal 2H-NbSe2 and 4H-NbSe2 phases, and characteristic Raman and XPS spectra typical for crystalline NbSe2 were obtained. The environmental sensitivity of the grown crystals is manifested by luminescence attributed to oxidized Nb at the samples' surface.