Platinum diselenide (PtSe _2 ) is a promising material for next-generation optoelectronic and electronic devices. Scalable production of high-quality PtSe _2 is therefore highly desirable. Consequently, thin-film growth techniques such as chemical vapor deposition and thermally assisted conversion (TAC) have gained increasing attention. In this study, we employed real-time, in-situ grazing-incidence wide-angle x-ray scattering to characterize the PtSe _2 growth process via TAC of pre-deposited Pt layers. We directly monitored the phase formation of PtSe _2 through its prominent 001 diffraction peak. Tracking the crystallization of few-layer PtSe _2 layers in real-time allowed us to estimate the activation energy using the Avrami crystallization model. We also identified a minimum temperature for obtaining the crystalline phase. Growth of horizontally aligned PtSe _2 was observed without the presence of any metastable transition phase throughout the selenization process. Higher growth temperatures drive anisotropic lattice evolution in PtSe _2 , resulting in reduced thickness and reduced lattice mismatch through lattice rotation.

This study addresses key challenges in gas sensing, particularly achieving high sensitivity at low operating temperatures. Tungsten disulfide (WS2) thin films were deposited by sputtering and sulfurized at 800 °C for 30 and 60 min on quartz and sapphire substrates. Raman spectroscopy confirmed multilayer WS2 formation, with characteristic modes at 349 and 417 cm-1. X-ray diffraction revealed that the films are polycrystalline with the formation of the hexagonal 2H-WS2 phase on both substrates. FESEM images showed clearly visible nanoparticles, but they were not evenly distributed and were differently oriented, with a hint of texturing. The WS2 films exhibited stable sensing performance at low operating temperatures from 30 to 150 °C and high sensitivity toward NH3 in the 10-200 ppm range. Experimental results indicate a limit of detection, highlighting the potential of WS2 films for low operating temperature ammonia sensing. A minimum value of the limit of detection of 0.6 ppm for an operating temperature of 150 °C was achieved for the WS2 sample sulfurized at 800 °C for 60 min on a quartz substrate.

The chemical vapor deposition (CVD) technique is widely used to prepare transition metal dichalcogenide (TMD) thin films. Parameters such as precursors, type of substrate, temperature profile, gas flow through the CVD chamber and pressure can influence the orientation of TMD crystals in a thin film. In this context, the grazing-incidence wide-angle X-ray scattering (GIWAXS) technique serves as a promising tool for revealing the texture and spatial distribution of TMD crystalline domains in thin films. Here, a laboratory GIWAXS-based method is reported for the measurement of pole figures of textured TMD thin films. Additionally, GIWAXS tomography in grazing-incidence mode enables spatial mapping of the TMD crystalline domains in thin films. This unique combination of GIWAXS tomography and pole figure measurements allows advanced laboratory analysis of thin TMD films that was previously only possible on synchrotron beamlines.

A binder-free synthesis strategy is developed to directly fabricate MoO3/MoS2 heterostructures on molybdenum foil via sequential surface activation, thermal oxidation, and hydrazine-assisted hydrothermal conversion. Systematic optimization demonstrates that KOH activation followed by subsequent oxidation forms a hierarchical MoO3 scaffold, while hydrazine-assisted hydrothermal treatment deposits conformal MoS2 nanosheets, yielding a robust heterostructured electrode. The optimized electrode exhibits an exceptional specific capacitance of 997.3 F g-1 at 1 A g-1 when integrated into an asymmetric supercapacitor device (MoO3/MoS2||activated carbon, 1 ᴍ Na2SO4 aqueous electrolyte). Our heterostructure delivers outstanding cycling stability with 97% capacitance retention after 100 000 cycles. Electrochemical impedance spectroscopy reveals low internal resistance and greatly suppressed charge-transfer resistance, supporting rapid pseudocapacitive charge storage suggested by cyclic voltammetry and galvanostatic charge-discharge profiles. The process utilizes the molybdenum foil both as precursor and current collector, eliminating the need for polymer binders and enabling a scalable approach to mechanically stable, high surface area electrodes decorated with MoS2 nanocrystals for long-life aqueous hybrid supercapacitors.

Two-dimensional (2D) semiconductors have attracted significant attention for next-generation electronic applications. Among them, platinum diselenide (PtSe2) stands out due to its high predicted carrier mobility and its unique thickness-dependent electronic properties, transitioning from semiconducting behavior in ultrathin layers to semimetallic characteristics in thicker films.In this work, we report a transfer-free, lithography-compatible fabrication approach for PtSe2 field-effect transistors directly on Si/SiO2 substrates. The method exploits the intrinsic thickness-dependent properties of PtSe2 to realize homostructure devices, where thin regions act as the semiconducting channel and thicker regions serve as conductive contacts. Device structures are defined by conventional photolithography and lift-off of Pt, followed by a single selenization step that converts the patterned metal into PtSe2. Importantly, the selenization process constitutes the final fabrication step, preventing further processing-induced degradation of the ultrathin channel.The proposed strategy is compatible with standard microfabrication processes and enables deterministic patterning of device architectures. This transfer-free approach provides a promising route toward scalable integration of PtSe2-based electronics and advances the practical implementation of 2D semiconductor technologies.

This study presents the Raman spectral characteristics and selected electrical parameter measurements of WS2 films deposited by magnetron sputtering on sapphire and subsequently sulfurized. The analysis of the Raman spectra focuses on the positions and shifts of the E12g and A1g vibrational modes. The effects of different sputtering times on WS2 films and the corresponding activation energy values were also investigated. From both physical and experimental perspectives, the Raman spectral features of WS2 films were found to depend on the laser excitation wavelengths (532 nm and 632.8 nm) as well as on possible crystallographic defects and variations in the excitation point position. These defects have a significant influence on both the Raman spectra and the activation energies of the studied samples. The calculated activation energies (~ 0.15–0.19 eV) of the conduction charge carriers correlate with shallow defect-related energy levels indicated by the Raman characteristics.

In this contribution, our primary objective is to comprehensively examine the influence of sulfurization temperature on the optical properties of WS2 thin films deposited on quartz/sapphire substrates. We employed dc-magnetron sputtering for the deposition of WS2 thin films into the targeted substrates and then we prepared our samples at different sulfurization temperatures, 600 degrees C, 700 degrees C, and 800 degrees C. The characterization of the samples was performed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and Raman spectroscopy. Additionally, optical transmittance measurements were employed to further analyze the optical properties of the samples, with the Tauc plot method being utilized to determine the bandgap of each sample. The samples consist of flakes and films ranging in size from less than 30 nm to over 3 mu m, with a uniform thickness of 10 nm. Raman spectroscopy revealed the presence of the characteristic vibrational modes E-12g and A(1g) at approximately 350 and 419 cm-1, respectively, confirming the formation of a layered structure in all samples. The bandgap values obtained for the samples were in the range of 1.87 to 1.95 eV. The experimental findings demonstrate that variations in sulfurization temperature and substrate choice significantly influence the size, morphology, and density of the films and flakes, thereby impacting the optical properties, particularly the bandgap.

Combining diamond and two-dimensional materials is attracting increasing attention for synergic effects that have the best of both worlds. Applications range from electronics and quantum technologies to catalysis, energy conversion, and biosensors. Here, heterostructures based on hydrogenated diamond microcrystalline thin films with attached MoS2 nanosheets are formed by a single-zone annealing at atmospheric pressure. By varying the process parameters, MoS2 sheets are controllably synthesized in a vertical or horizontal orientation with respect to the diamond grain facets, which leads to a pronounced impact on the electronic and optoelectronic properties of the heterostructures. Raman, SEM, AFM, KPFM, and SKP analyses show the influence of the MoS2 orientation and thickness on the work function, surface potential, spatially and spectrally resolved photovoltage, and charge transfer kinetics. The aligned growth of MoS2 nanosheets and their properties are elucidated by molecular mechanics and time-dependent DFT calculations, which explain the mechanism of the assembly and the related optoelectronic effects in a straightforward way. The major switching point occurs precisely at 11 nm of the MoS2 thickness/length. The highest photoresponse of 350 meV and favorable charge transfer are observed for the vertical MoS2 arrangement on diamond, yet without a covalent bond. The results and theoretical model hint at broader implications beyond the MoS2-diamond system.

Supercapacitors are vital for modern energy storage systems due to their high power density and long operational lifespan. In this study, we investigate the use of molybdenum trioxide (MoO3) microstructures for supercapacitor applications. MoO3 exhibits favourable properties such as low serial resistance, high conductivity, and the possibility of high surface area. These properties enhance the overall electrochemical performance of such supercapacitors. The study focuses on optimizing MoO3 preparation via oxidation at various temperatures. It was found that the orthorhombic phase of MoO3, formed at 500 °C, provided the best performance with a specific capacitance of 179.2 F/g (933 mF/cm2) and the lowest serial resistance. Furthermore, the chemical activation of the surface by immersion in 1 M potassium hydroxide significantly increased the surface area, as confirmed by scanning electron microscopy. This hydroxide activation also led to a rise in specific capacitance, reaching 201.7 F/g (902 mF/cm2). The findings presented in this work suggest that the combination of optimal oxidation conditions and surface activation via KOH immersion can lead to enhanced energy storage capacity in such supercapacitor structures.

Currently, great emphasis is placed on air quality and the presence of pollutants, whether on toxic substances (NH3 or CO), substances that reduce the quality of life (CO2) or chemical vapors from industries (acetone or ethanol). Attention is therefore focused on new gas-sensing materials enabling detection even at low (up to room) temperatures with sufficient response and short reaction time. Here, we investigate the suitability of hydrogen-terminated nanocrystalline diamond (H-NCD) films and their heterostructures with molybdenum disulfide (MoS2), graphene oxide (GO), reduced GO (rGO), thiol-functionalized GO (SH-GO), or gold nanoparticles (Au NPs) for gas sensing applications. Electrical properties are measured for oxidizing gas NO2, reducing gas NH3, and chemical vapor of ethanol (C2H5OH), and at temperatures varied from room temperature to 125 degrees C. All tested gases were used with a concentration of up to 100 ppm. Synthetic air is used as the flushing gas. The measured parameters of the tested sensors are compared, both with each other and with commercial sensors, and subsequently evaluated. In contrast to the individual forms of employed materials with limited response to the exposed gases, the H-NCD heterostructures revealed better sensing properties. In particular, the Au NPs/H-NCD heterostructures revealed a higher response at 125 degrees C in contrast to H-NCD, MoS2/H-NCD had quite good response even at room temperature and GO/H-NCD revealed high sensitivity to chemical vapor, which further improved for the SH-GO/H-NCD.

Molybdenum disulfide is a promising candidate for various applications in electronics, optoelectronics, or alkali-ion batteries. The natural presence of the van der Waals gap allows intercalating alkali ions, such as lithium, into MoS2 films. Intercalation can modify the electronic structure as well as the electrical and optical properties. Here, we present a structural, optical, and electrical characterization of Li-intercalated few-layer MoS2 films. The intercalation was carried out by annealing MoS2 film in the presence of Li2S powder, serving as a lithium source. The initial MoS2 layers were prepared by pulsed laser deposition (PLD) and by sulfurization of 1 nm thick Mo film (TAC). The presence of lithium was confirmed by synchrotron-based x-ray Photoelectron Spectroscopy. The Raman spectroscopy, x-ray diffraction, and optical absorption measurements confirmed semiconducting behavior for all samples. All samples exhibited the thermally activated dependence of the electrical resistance, R, typical for the Efros–Shklovskii variable range hopping in a disordered semiconductor, ln R(T) ∝ (TES/T)1/2, where kBTES is the hopping activation energy. The PLD-grown MoS2 samples exhibited a relatively mild initial disorder primarily caused by grain boundaries. Lithium intercalation led to an increase in disorder, evident in the increase in kBTES and a substantial rise in electrical resistance. The TAC-grown undoped MoS2 sample already exhibited significant resistance, and the impact of Li intercalation on resistance was minimal. This observation was attributed to the fact that the TAC-grown MoS2 samples exhibit a perturbed stoichiometry (the S:Mo ratio ∼ 2.20), causing strong disorder even before Li intercalation. The electron doping caused by lithium, if any, was completely obscured by the effect of disorder.

Pole figure of the 10−13 diffraction of hexagonal MoTe2 obtained from the GIWAXS measurement.

Nowadays, 2D materials are one of the most studied classes of materials.In addition to the most famous graphene, progress has been achieved in studying and using fundamental properties of transition metal dichalcogenides (TMD).Complementary, diamond as a representative of 3D materials has gained a reputation as an extremely versatile material due to its extraordinary combination of physical/chemical/electrical/optical properties.Besides these particular forms of 2D and 3D materials, their heterostructures have become very attractive due to new phenomena and functions (bandgap engineering, enhanced charge transport, optical interaction, etc.).However, individual technological procedures are still minimally investigated and described.Here, we will demonstrate a proof-of-concept for the preparation of MoS2/diamond heterostructures, where two different strategies were employed: a) growth of MoS2 layers on diamond films, and b) growth of diamond films on Si/MoS2 substrates.Considering the growth conditions for MoS2 and diamond materials, heterostructures based on MoS2 on diamond can be prepared more easily.Regardless of the diamond film's morphology, the grown MoS2 layer simply copies the diamond surface and does not damage the diamond film.However, the heterostructure in the configuration of diamond on MoS2 is a highly challenging task.It was found experimentally that the combination of deposition temperature and aggressive chemical-plasma environment during diamond growth places high demands on the resistance and stability of MoS2 layers.

Nickel-based sulfides (particularly NiS 2 ) are regarded as promising materials for highly efficient electrochemical generation and storage devices. The conventional fabrication methods of nanostructured NiS X electrodes involve several complex steps using multiple precursors and techniques. In this paper, the NiS X electrodes are prepared by a plain one-step process of one-zone sulfurization of Ni foam. The evolution of highly electroactive 2D-nanoflakes reliant on sulfurization temperature is studied. Scanning electron microscopy, x-ray diffractometry, and energy-dispersive x-ray spectroscopy confirmed the presence of NiS X (x = 1 and 2) in the prepared structures. A strong dependence of sample morphology and 2D-nanoflakes density on sulfurization temperature was demonstrated. The electrochemical properties of samples were characterized by cyclic voltammetry and electrochemical impedance spectroscopy measurements. Owing to the 2D-nanoflake structure, the NiS 2 showed attractive electrochemical performance, including a high specific capacitance of 648 mF cm −2 and a capacitance retention rate of 90,7% after 3000 cycles. Our study shows that the composition and crystal growth of NiS X can be tuned by reaction temperature during the sulfurization and high perspective of sulfurization in the synthesis of highly electroactive large-scale electrodes for supercapacitors.

Molybdenum ditelluride (MoTe2), a member of the transition metal dichalcogenide family, holds significant promise in optoelectronic applications. To harness its full potential, it is imperative to understand its fundamental optical properties, including refractive indices. Herein, measurements of the transmittance and reflectance spectra of thin MoTe2 layers are conducted featuring hexagonal and monoclinic structures across the far‐infrared (IR) and mid‐IR spectral regions. These spectra are fitted, allowing to extract the complex refractive index and optical conductance. In the semiconducting hexagonal phase, both the conductance and extinction coefficient remain negligible below 3000 cm−1 and increase at higher energies. Conversely, the monoclinic phase exhibits a conductance peak in the far‐IR region and a continuous increase from 1000 to 6000 cm−1. The findings are compared with existing theoretical and experimental results to provide further insights into MoTe2's optical behavior.

The self-decomposition reaction of the nickel ammonia complex was used for the nickel hydroxide formation on the nickel foam with further modification in several ways. The addition of polyvinyl pyrrolidone (PVP) and the electrochemical or chemical activation with cobalt hydroxide was used to modify the formation method. In all cases, structures with Ni(OH)(2) nanoflakes were formed. It was found that the flower-like particles of Co(OH)(2) were precipitated during chemical activation among the nanoflakes. It was shown that the presence of PVP during the nickel ammonia complex decomposition suppressed the highly branched particles. The absence of the highly branched particles increased the capacitive properties of the formed electrode at high current densities. The highest capacitance in 1408 F/g at 1 A/g was shown for the sample precipitated with the PVP presence and the further chemical activation by cobalt.

Molybdenum disulfide (MoS2) and nanocrystalline diamond (NCD) have attracted considerable attention due to their unique electronic structure and extraordinary physical and chemical properties in many applications, including sensor devices in gas sensing applications. Combining MoS2 and H-terminated NCD (H-NCD) in a heterostructure design can improve the sensing performance due to their mutual advantages. In this study, the synthesis of MoS2 and H-NCD thin films using appropriate physical/chemical deposition methods and their analysis in terms of gas sensing properties in their individual and combined forms are demonstrated. The sensitivity and time domain characteristics of the sensors were investigated for three gases: oxidizing NO2, reducing NH3, and neutral synthetic air. It was observed that the MoS2/H-NCD heterostructure-based gas sensor exhibits improved sensitivity to oxidizing NO2 (0.157%·ppm-1) and reducing NH3 (0.188%·ppm-1) gases compared to pure active materials (pure MoS2 achieves responses of 0.018%·ppm-1 for NO2 and -0.0072%·ppm-1 for NH3, respectively, and almost no response for pure H-NCD at room temperature). Different gas interaction model pathways were developed to describe the current flow mechanism through the sensing area with/without the heterostructure. The gas interaction model independently considers the influence of each material (chemisorption for MoS2 and surface doping mechanism for H-NCD) as well as the current flow mechanism through the formed P-N heterojunction.

Molybdenum disulfide (MoS2) few-layer films have gained considerable attention for their possible applications in electronics and optics and also as a promising material for energy conversion and storage. Intercalating alkali metals, such as lithium, offers the opportunity to engineer the electronic properties of MoS2. However, the influence of lithium on the growth of MoS2 layers has not been fully explored. Here, we have studied how lithium affects the structural and optical properties of the MoS2 few-layer films prepared using a new method based on one-zone sulfurization with Li2S as a source of lithium. This method enables incorporation of Li into octahedral and tetrahedral sites of the already prepared MoS2 films or during MoS2 formation. Our results discover an important effect of lithium promoting the epitaxial growth and horizontal alignment of the films. Moreover, we have observed a vertical-to-horizontal reorientation in vertically aligned MoS2 films upon lithiation. The measurements show long-term stability and preserved chemical composition of the horizontally aligned Li-doped MoS2.

The few-layer transition metal dichalcogenides (TMD) are an attractive class of materials due to their unique and tunable electronic, optical, and chemical properties, controlled by the layer number, crystal orientation, grain size, and morphology. One of the most commonly used methods for synthesizing the few-layer TMD materials is the chemical vapor deposition (CVD) technique. Therefore, it is crucial to develop in situ inspection techniques to observe the growth of the few-layer TMD materials directly in the CVD chamber environment. We demonstrate such an in situ observation on the growth of the vertically aligned few-layer MoS2 in a one-zone CVD chamber using a laboratory table-top grazing-incidence wide-angle X-ray scattering (GIWAXS) setup. The advantages of using a microfocus X-ray source with focusing Montel optics and a single-photon counting 2D X-ray detector are discussed. Due to the position-sensitive 2D X-ray detector, the orientation of MoS2 layers can be easily distinguished. The performance of the GIWAXS setup is further improved by suppressing the background scattering using a guarding slit, an appropriately placed beamstop, and He gas in the CVD reactor. The layer growth can be monitored by tracking the width of the MoS2 diffraction peak in real time. The temporal evolution of the crystallization kinetics can be satisfactorily described by the Avrami model, employing the normalized diffraction peak area. In this way, the activation energy of the particular chemical reaction occurring in the CVD chamber can be determined.

This paper is dedicated to the fabrication and characterization of NiSx supercapacitor electrodes prepared from Ni-foam by means of a one-zone sulfurization process. The successful preparation of NiSx (x= 1 and 2) was confirmed by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). A specific capacitance of 105 mF/cm 2 and 510 mF/cm 2 was achieved on electrodes prepared at 400°C and 250 °C, respectively. Anodic and cathodic peaks indicate the pseudo-capacitive character of the charge storage mechanism for both samples prepared at different sulfurization temperature. It is proposed that the 4.9 times higher capacitance of sample prepared at 250°C is associated with a higher density of nickel sulfide nanoflakes in the structure.