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In this work, the potential of 2D semi‐metallic PtSe2 as source/drain (S/D) contacts for 2D material field‐effect‐transistors (FETs) through theoretical and experimental investigations, is explored. From the density functional theory (DFT) calculations, semi‐metallic PtSe2 can inject electrons and holes into MoS2 and WSe2, respectively, indicating the feasibility of PtSe2 contacts for both n‐ and p‐metal‐oxide‐semiconductor FETs (n‐/p‐MOSFETs). Indeed, experimentally fabricated flake‐level MoS2 n‐MOSFETs and WSe2 p‐MOSFETs exhibit a significant reduction in contact resistance with semi‐metallic PtSe2 contacts compared to conventional Ti/Au contacts. To demonstrate the applicability for large‐area electronics, MoS2 n‐MOSFETs are fabricated with semi‐metallic PtSe2 contacts using chemical vapor deposition‐grown MoS2 and PtSe2 films. These devices exhibit outstanding performance metrics, including high on‐state current (≈10−7 A/µm) and large on/off ratio (>107). Furthermore, by employing these high‐performance MoS2 n‐MOSFETs, vertically stacked n‐MOS inverters are successfully demonstrated, suggesting that 3D integration of 2D material FETs is possible using semi‐metallic PtSe2 contacts. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction (HER) in alkaline electrolytes using transition metal dichalcogenides is a research area that is not tapped into. Alkaline HER (2H2O+2e-→H2+OH- ${{2H}_{2}O+2{e\ }^{-}\to {H}_{2}+{OH}^{-}{\rm \ }}$) is harder to achieve relative to acidic HER (H++2e-→H2 ${{H}^{+}+2{e\ }^{-}\to \ {H}_{2}}$), this is attributed to the additional water dissociation step that occurs in basic HER to generate H+ ions. In fact, for most catalysts, their HER activity decreases tremendously when the electrolyte is changed from acidic to basic conditions. Platinum dichalcogenides, PtX2 (X=S, Se, Te), are an interesting member of transition metal dichalcogenides (TMDs) as these show an immense hybridization of the Pt d orbitals and chalcogen p orbitals because of closely correlated orbital energies. The trend in electronic properties of these materials changes drastically as the chalcogen is changed, with PtS2 reported to exhibit semi‐conductor properties, PtSe2 is semi‐metallic or semi‐conductive, depending on the number of layers, while PtTe2 is metallic. The effect of varying the chalcogen atom on the HER activity of Pt dichalcogenides will be studied. Pt dichalcogenides have previously been prepared by direct high‐temperature chalcogen deposition of Pt substrate and evaluated as electrocatalysts for HER in H2SO4. The previously employed synthesis procedures for PtX2 limit these compounds′ mass production and post‐synthesis treatment. In this study, we demonstrated, for the first time the preparation of PtSe2 and PtTe2 by colloidal synthesis. Colloidal synthesis offers the possibility of large‐scale synthesis of materials and affords the employment of the colloids at various concentrations in ink formulation. The electrochemical HER results acquired in 1 M KOH indicate that PtTe2 has a superior HER catalytic activity to PtSe2. A potential of 108 mV for PtTe2 and 161 mV for PtSe2 is required to produce a current density of −10 mA cm−2 from these catalysts. PtTe2 has a low Tafel slope of 79 mVdec−1, indicating faster HER kinetics on PtTe2. Nonetheless, the stability of these catalysts in an alkaline medium needs to be improved to render them excellent HER electrocatalysts. [ABSTRACT FROM AUTHOR]

Using density functional theory, the optoelectronic characteristics of PtSe2 and SnSe2 monolayers were investigated in this study. The calculated binding energies showed that the monolayers PtSe2 and SnSe2 are stable. By observing the phonon dispersion curve, it can be confirmed that these two monolayers are dynamically stable, as it was noted that all frequencies have positive values and there are no negative values for frequency. The frequency levels that were achieved, 1150 cm-1, were also noted. Bandgaps of 1.778 eV for SnSe2 and 2.418 eV for PtSe2 indicate that the monolayers are semiconductors. Optical characteristics predictions also indicate that PtSe2 and SnSe2 monolayers absorb light from infrared to ultraviolet light. Photocatalytic devices and visible light communication are two areas where the PtSe2 and SnSe2 monolayer structures are anticipated to shine. The remarkable characteristics of PtSe2 and SnSe2 monolayers have led to their anticipated use in a wide range of optical devices, catalysts, field effect transistors, solar cells and other similar applications. [ABSTRACT FROM AUTHOR]

Narrow bandgap 2D layered material platinum selenide (PtSe2) with good environmental stability, high carrier mobility, and high light absorption, has been widely investigated for uncooled midwave‐infrared (MWIR) photodetection. However, the phototransistor based on the PtSe2 operation at room temperature suffered from the high dark current and background noise. Here, a graphene (G)‐enhanced G‐WSe2/PtSe2 hetero‐diode placed on a metal electrode is reported. To enhance the photogain, a graphene layer placed on the WSe2/PtSe2 heterodiode as a local gating layer is designed. The device exhibits an ultra‐high light on/off ratio of up to 108 and ultra‐fast photoresponse speed with raising time τr = 0.9 µs and decay time of τd = 1.5 µs in the visible spectra range. Notably, ultrabroad band photoresponse from 405 to 3366 nm is demonstrated under the self‐power model. Notably, the device presented a competitive photovoltaic effect with a high energy conversion efficiency (PCE) of 3.45%. The results pave the way toward a new approach to tuning the performance of the atomic thin layered materials photodetector. [ABSTRACT FROM AUTHOR]

The emerging two-dimensional (2D) transition metal dichalcogenide PtSe 2 is a promising catalyst for hydrogen evolution reactions (HER). In this study, we performed density functional theory (DFT) calculations to investigate the mechanism conversion of the HER over PtSe 2 with respect to the changes in the number of layers of the catalyst. We found that the adsorption energy of hydrogen (ΔG H) changed with an increase in the number of 2D material layers, and the most significant change occurred when the number of layers was increased from one to two. Furthermore, we conducted dynamic calculations to reveal the mechanisms of the HER on the basal and V se surfaces. Owing to the changes in ΔG H , the HER mechanism undergoes a conversion between Volmer–Heyrovsky and Volmer–Volmer'–Tafel mechanisms. Through frontier orbitals analysis, layer-stacking altered the bonding capability between hydrogen and PtSe 2 surfaces by altering the electronic structure of the PtSe 2 surface. This study demonstrates the synergistic effect of interlayer interactions on the HER over PtSe 2 catalysts and can be helpful in stimulating innovative ideas for 2D material design. • DFT calculations unveil PtSe 2 's layer-dependent HER catalytic behavior. • Change in adsorption energy of hydrogen (ΔGH) varies significantly with PtSe 2 layering. • Dynamic simulations reveal distinct HER mechanisms on various PtSe 2 surfaces. • Layer-stacking modifies PtSe 2 's electronic structure, impacting hydrogen bonding. • Findings may inspire innovative approaches to designing 2D catalysts. [ABSTRACT FROM AUTHOR]

In recent years, 2D materials and their heterostructures have started to offer an ideal platform for high-performance photodetection devices. In this work, a highly responsive, self-powered photodetector based on PtSe2/MoS2 van der Waals heterostructure is demonstrated. The device achieves a noteworthy wide band spectral response from visible (405 nm) range to the near infrared region (980 nm). The remarkable photoresponsivity and external quantum efficiency up to 4.52 A/W, and 1880% are achieved, respectively, at 405 nm illumination with fast response time of 20 ms. In addition, the photodetector exhibits a decent photoresponsivity of 33.4 mA/W at zero bias, revealing the photodetector works well in the self-driven mode. Our work suggests that a PtSe2/MoS2 heterostructure could be a potential candidate for the high-performance photodetection applications. [ABSTRACT FROM AUTHOR]

Platinum selenide (PtSe2), an emerging 2D material, has attracted extensive attention owing to its wide‐tunable bandgap and ultrahigh conductivity for potential applications in optoelectronic and energy devices. However, the preparation of atomically thin PtSe2 remains a big challenge due to its large formation energy. Herein, the robust synthesis of large‐area ultrathin PtSe2 microbelts via a step‐induced separation growth strategy on Au(001) substrate is demonstrated. Thanks to the high controllability of this approach, the continuous modulation of the thickness of PtSe2 microbelts from monolayer to bulk is realized and the sample coverage from ≈5% to ≈100% by coordinately tuning the growth temperature and time. Theory calculations indicate that the significant reduction of formation energy of PtSe2 nucleation at the Au steps, along with the high‐efficiency separation‐supply of Pt precursor, are responsible for the robust synthesis of PtSe2. Owing to the rich‐edges with abundant active sites and metallic conduction features of ultrathin PtSe2 microbelt, it can act as an excellent electrocatalyst, featured with a record high hydrogen evolution reaction efficiency (Tafel slope: 37 mV dec−1). This work provides new insights into the highly efficient synthesis of large‐scale 2D materials for exploring their unique physics and fascinating applications. [ABSTRACT FROM AUTHOR]

Favorable growth of asymmetric hetero‐nanostructures consisting of plasmonic metals and semiconductors or topological nanomaterials is highly desired because the performance of nonlinear optical antennas is closely related to their composition and morphology symmetry. In this work, two methods are proposed to overgrow PtSe2, a semiconductor or topological semimetal material, onto Au nanorods (AuNRs) to form Au/AuPt/PtSe2 and Au/AgPtSe2 heterorods via wet chemical technique. Both Au/AuPt/PtSe2 and Au/AgPtSe2 heterorods show asymmetric morphologies: the Au/AuPt/PtSe2 heterorods show a partially hollow morphology with an etched AuNR coated by AuPt and PtSe2 shells; the Au/AgPtSe2 heterorods prepared by Ag‐mediated overgrowth method have a toothbrush shape with AgPtSe2 attached on the side surface near one end of AuNRs. The two asymmetric heterorods show significantly enhanced nonlinear radiations of second harmonic generation with the excitation laser wavelength tuning from 1220 to 1315 nm, and a maximal nonlinear enhancement factor of 16 is achieved, which is attributed to the interaction of gold core with platinum selenide shell and the broken symmetry of heterostructures. The findings provide a strategy to prepare metal‐topological heterostructures as optical antennas with optimized performance in the application of nonlinear photonic nanodevices. [ABSTRACT FROM AUTHOR]

Due to the narrow bandgap, environment stability, and Pt vacancy‐induced magnetism, PtSe2 has been considered a promising candidate for future broadband photodetection and electronics. However, the growth of single‐crystal PtSe2 is still a challenge. Herein, the synthesis of hexagonal and tetragonal 2H─PtSe2 single‐crystal flakes by precisely tailoring the growth temperature is reported. Through atomic structure analysis, hexagonal and tetragonal flakes are proven c‐axis and a‐axis orientations of 2H─PtSe2, indicating the preferred nucleation orientations are along the basal plane and vertically basal plane, respectively. The crystalline orientation‐dependent properties are studied including high‐pressure and polarized in situ‐Raman, electrical transport. The out‐of‐basal plane vibration (A1g) is sensitive to pressure showing 2.744 and 3.282 cm−1 GPa−1 corresponding to c‐2H─PtSe2 and a‐2H─PtSe2, respectively. The conductivity of c‐2H─PtSe2 is 57 times higher than that of a‐2H─PtSe2. Furthermore, by studying magnetic transport at low temperatures, both c‐2H─PtSe2 and a‐2H─PtSe2 exhibit butterfly‐shaped magnetoresistance hysteresis suggesting their ferromagnetic property. The c‐2H─PtSe2 has a higher |MR| ratio and higher coercive field compared with a‐2H─PtSe2, indicating that across multilayer carrier regulation for c‐2H─PtSe2 is more difficult than intra‐layer carrier regulation for a‐2H─PtSe2. This study opens the way to grow different crystalline orientations of 2D materials and will bring more abundant properties. [ABSTRACT FROM AUTHOR]

The development of simple and efficient visible light photocatalytic catalysts for hydrogen production from water is an important development direction in the field of photocatalysis, and composite two-dimensional materials are found to be promising candidates. This paper constructs a novel two-dimensional MoSe 2 /PtSe 2 type-II heterojunction and systematically studies its geometric structure, electronic structure, and optical properties by first-principles calculation. It is evident that the heterojunction has good thermodynamic, kinetic, and mechanical stability, as well as excellent hole carrier mobility, which is conducive to the separation of photogenerated electrons and holes. The optical properties show that MoSe 2 /PtSe 2 heterojunction has the best optical absorption efficiency for visible light and has the ability to cross the water-cracking oxidation-reduction potential at pH = 4. More importantly, the MoSe 2 /PtSe 2 heterojunction shows great hydrogen absorption reaction performance, indicating that it is a potential photocatalyst for overall water splitting of visible light, and has broad application prospects in the field of photocatalysis and optoelectronics. [Display omitted] • The design of a novel type-II MoSe 2 /PtSe 2 heterojunction. • MoSe 2 /PtSe 2 heterostructure can drive overall water splitting at pH = 4. • Thermodynamic feasibilities of HER and OER are confirmed by the Gibbs free energies. • This work broadens the field of vision for the preparation of highly efficient photocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, we propose an optically controlling broadband terahertz modulator of a layer-dependent PtSe2 nanofilm based on a high-resistance silicon substrate. Through optical pump and terahertz probe system, the results show that compared with 6-, 10-, and 20-layer films, a 3-layer PtSe2 nanofilm has better surface photoconductivity in the terahertz band and has a higher plasma frequency ωp of 0.23 THz and a lower scattering time τs of 70 fs by Drude–Smith fitting. By the terahertz time-domain spectroscopy system, the broadband amplitude modulation of a 3-layer PtSe2 film in the range of 0.1–1.6 THz was obtained, and the modulation depth reached 50.9% at a pump density of 2.5 W/cm2. This work proves that PtSe2 nanofilm devices are suitable for terahertz modulators. [ABSTRACT FROM AUTHOR]

PtSe _2 has high carrier mobility, excellent electrical and optical properties, and high potential in the field of optoelectronic devices. In this paper, the conventional selenization method is optimized and a single-temperature zone preparation is used to prepare large-area and homogeneous PtSe _2 thin-film materials on sapphire substrates in a shorter time and at a lower temperature. The prepared sample is characterized by optical microscopy, atomic force microscopy, Raman spectroscopy and Z-scan method. The saturable absorption properties of layered PtSe _2 as a passive Q-switched are investigated in a solid-state laser. The results show that the PtSe _2 thin film material is synthesized at 400 °C for 1 h to cover the entire one-inch sapphire wafer with a thickness of about 25 nm and the surface roughness is 13.1 nm. The modulation at 1064 nm yielded an output pulse with a maximum repetition frequency of 688.47 kHz, corresponding to a pulse width of 202.5 ns, a peak power of 7.35 W, a single-pulse energy of 1.51 μJ, and a stable pulse train.

Semiconductive transition metal dichalcogenides (TMDs) have been considered as next generation semiconductors, but to date most device investigations are still based on microscale exfoliation with a low yield. Wafer scale growth of TMDs has been reported but effective doping approaches remain challenging due to their atomically thick nature. This work reports the synthesis of wafer-scale continuous few-layer PtSe2 films with effective doping in a controllable manner. Chemical component analyses confirm that both n-doping and p-doping can be effectively modulated through a controlled selenization process. The electrical properties of PtSe2 films have been systematically studied by fabricating top-gated field effect transistors (FETs). The device current on/off ratio is optimized in two-layer PtSe2 FETs, and four-terminal configuration displays a reasonably high effective field effect mobility (14 and 15 cm2 V−1 s−1 for p-type and n-type FETs, respectively) with a nearly symmetric p-type and n-type performance. Temperature dependent measurement reveals that the variable range hopping is dominant at low temperatures. To further establish feasible application based on controllable doping of PtSe2, a logic inverter and vertically stacked p–n junction arrays are demonstrated. These results validate that PtSe2 is a promising candidate among the family of TMDs for future functional electronic applications.

Grain boundaries in two-dimensional (2D) semiconductors generally induce distorted band alignment and interfacial charge, which impair their electronic properties for device applications. Here, we report the improvement of band alignment at the grain boundaries of PtSe2, a 2D semiconductor, with selective adsorption of a presentative organic acceptor, tetracyanoquinodimethane (TCNQ). TCNQ molecules show selective adsorption at the PtSe2 grain boundary with strong interfacial charge. The adsorption of TCNQ distinctly improves the band alignment at the PtSe2 grain boundaries. With the charge transfer between the grain boundary and TCNQ, the local charge is inhibited, and the band bending at the grain boundary is suppressed, as revealed by the scanning tunneling microscopy and spectroscopy (STM/S) results. Our finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules, improving the electronic properties of 2D semiconductors for their future applications. [ABSTRACT FROM AUTHOR]

The analysis aims to enhance the sensitivity of the surface plasmon resonance-based sensor. The proposed sensor consists of a single layer of Ag metal, black phosphorus (BP), and Platinum diselenide (PtSe2). The thickness of the Ag metal is considered as 45 nm. The study was carried out using attenuated total reflection. The refractive index of the sensor changes when analyte or biomolecules comes in contact with the sensing layer. The thickness of the BP layer has been taken as 0.34 nm. The maximum sensitivity of the sensor is achieved for one layer of PtSe2 and two layers of BP. The calculated performance parameters, sensitivity, figure of merit, and detection accuracy, are 275.2 Degree / RIU , 43.1 RIU - 1 , and 0.16 Degree - 1 , respectively. The sensitivity of the proposed sensor is 1.38 times the conventional sensor. [ABSTRACT FROM AUTHOR]

Unipolar barrier architecture is designed to enhance the photodetector's sensitivity by inducing highly asymmetrical barriers, a higher barrier for blocking majority carriers to depressing dark current, and a low minority carrier barrier without impeding the photocurrent flow through the channel. Depressed dark current without block photocurrent is highly desired for uncooled Long-wave infrared (LWIR) photodetection, which can enhance the sensitivity of the photodetector. Here, an excellent unipolar barrier photodetector based on multi-layer (ML) graphene (G) is developed, WSe 2 , and PtSe 2 (G-WSe 2 -PtSe 2 ) van der Waals (vdW) heterostructure, in which extremely low dark current of 1.61×10 -13 A, a record high light on/off ≈10 9 are demonstrated at 0 V. Notably, the device exhibits ultrafast response speed with rise time τ r = 699 ns and decay time τ d = 452 ns and high-power conversion efficiency (η) of 4.87%. The heterostructure demonstrates a broadband photoresponse from 365 nm to LWIR 10.6 µm at room temperature. Notably, the G-WSe 2 -PtSe 2 nBn device demonstrates high photoresponsivity (R) of 1.8 AW -1 with 10.6 µm laser at 1 V bias in ambient air. This unipolar barrier device architecture offers an alternative way for highly sensitive free space communication., (© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Metal conversion processes have been instrumental in advancing semiconductor technology by facilitating the growth of thin-film semiconductors, including metal oxides and sulfides. These processes, widely used in the industry, enhance the semiconductor manufacturing efficiency and scalability, offering convenience, large-area fabrication suitability, and high throughput. Furthermore, their application to emerging two-dimensional (2D) semiconductors shows promise in addressing spatial control and layer number control challenges. In this work, we designed a multi-step metal conversion process for 2D materials to synthesize a high-quality and ultrauniform film. PtSe 2 is introduced to utilize its wide-band-gap tunability, which exhibits both semiconductor and metallic properties. Our multi-step-grown PtSe 2 film shows extremely low roughness ( R a = 0.107 nm) and improved interlayer quality compared to the single-step PtSe 2 film. Additionally, we explored the growth mechanism of the metal conversion process and how the multi-step method contributes to the thickness uniformity of the film. We demonstrated a thin PtSe 2 channel field-effect transistor (FET) array with p-type behavior with a maximum on/off ratio ∼10 3 . The FET fabricated by the MoS 2 channel with the semimetallic multi-step PtSe 2 electrode shows an enhanced performance in mobility and contact resistance compared to the conventional single-step PtSe 2 electrode FET.

As a novel transition metal dichalcogenide material with high carrier mobility, adjustable band gap and excellent stability, the photocarrier ultrafast dynamics of PtSe2 films with the different thickness is researched by ultrafast transient absorption spectrum and optical pump and terahertz probe spectrum. The experimental results show that the few-layer PtSe2 films present semiconductor phase which exhibits a triple exponential decay process, while multi-layer of PtSe2 films present semi-metallic phase which exhibits a double exponential decay process. And the principle of light response and carrier dynamics of PtSe2 films after excitation is analyzed, one found that the defect state carrier recombination exists in all samples. The carrier relaxation is dominated by Auger exciton–exciton annihilation in few-layer PtSe2 film, and the defect state of multiple-layer PtSe2 film plays a dominant role in the photo carrier relaxation, which is promising to a further application in modulators and detectors for characterizing the transition from semiconductor to semi-metal by controlling its film thickness.

PtSe2 is one of the most promising materials for the next generation of piezoresistive sensors. However, the large‐scale synthesis of homogeneous thin films with reproducible electromechanical properties is challenging due to polycrystallinity. It is shown that stacking phases other than the 1T phase become thermodynamically available at elevated temperatures that are common during synthesis. It is shown that these phases can make up a significant fraction in a polycrystalline thin film and discuss methods to characterize them, including their Seebeck coefficients. Lastly, their gauge factors, which vary strongly and heavily impact the performance of a nanoelectromechanical device are estimated. [ABSTRACT FROM AUTHOR]

This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide (PtSe2) nanoribbon arrays with anisotropic conductivity. The anisotropic properties of two-dimensional (2D) materials, especially transition-metal dichalcogenides (TMDs), have attracted great interest in research. The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications, such as nanoelectronics and optoelectronics. One-dimensional (1D) nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures, providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality. The natural alignment of zigzag (ZZ) PtSe2 nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy (ARPRS), and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory (DFT). Back-gate field-effect transistors (FETs) are also constructed of unidirectional PtSe2 nanoribbons to investigate their anisotropic electrical properties, which align with the results of the projected density of states (DOS) calculations. This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives. [ABSTRACT FROM AUTHOR]

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An emerging subclass of transition-metal dichalcogenides (TMDs), noble-transition-metal dichalcogenides (NMDs), has led to an increase in nanoscientific research in two-dimensional (2D) materials. NMDs feature a unique structure and several useful properties. 2D NMDs are promising candidates for a broad range of applications in areas such as photodetectors, phototransistors, saturable absorbers, and meta optics. In this review, the state of the art of 2D NMDs research, their structures, properties, synthesis, and potential applications are discussed, and a perspective of expected future developments is provided. [ABSTRACT FROM AUTHOR]

Understanding the transition from nonplanar to planar clusters is crucial for the controllable synthesis of transition metal dichalcogenide (TMDC) monolayers. Using PtSe 2 as a model, we investigate how the chemical environment influences the nucleation and growth stages of monolayer PtSe 2 through structure searching and first-principles calculations. We established a comprehensive database of platinum selenide clusters (Pt x Se y , x = 1-10), analyzing 2095 unique clusters and identifying 191 stable isomers and 63 structures with the lowest formation energy on the convex hull. Our findings reveal a chemical environment-dependent phase transition from 3D structures to the planar T-phase of Pt x Se y clusters, representing an evolutionary route for PtSe 2 growth. Clusters such as PtSe 6 , Pt 2 Se 9 , Pt 3 Se 10 , and Pt 7 Se 10 in Pt-rich environments, as well as Pt 2 Se 15 and Pt 10 Se 32 in Se-rich environments, have been found to exhibit high stability. Additionally, the impact of varying chemical potentials of Pt and Se on the stability of these clusters is explored. PtSe 4 and PtSe 6 are found to be highly stable under most experimentally achievable chemical potential conditions and may serve as dominant precursors during PtSe 2 growth. This work advances our understanding of the nucleation processes of PtSe 2 and other T-phase TMDC materials.

Ultrathin PtSe 2 ribbons can host spin-polarized edge states and distinct edge electrocatalytic activity, emerging as a promising candidate for versatile applications in various fields. However, the direct synthesis is still challenging and the growth mechanism is still unclear. Herein, the arrayed growth of ultrathin PtSe 2 ribbons on bunched vicinal Au(001) facets, via a facile chemical vapor deposition (CVD) route is reported. The ultrathin PtSe 2 flakes can transform from traditional irregular shapes to desired ribbon shapes by increasing the height of bunched and unidirectionally oriented Au steps (with step height h step ) is found. This crossover, occurring at h step ≈ 3.0 nm, defines the tailored growth from step-flow to single-terrace-confined modes, as validated by density functional theory calculations of the different system energies. On the millimeter-scale single-crystal Au(001) films with aligned steps, the arrayed ultrathin PtSe 2 ribbons with tunable width of ≈20-1000 nm, which are then served as prototype electrocatalysts for hydrogen evolution reaction (HER) is achieved. This work should represent a huge leap in the direct synthesis and the mechanism exploration of arrayed ultrathin transition-metal dichalcogenides (TMDCs) ribbons, which should stimulate further explorations of the edge-related physical properties and practical applications., (© 2024 Wiley‐VCH GmbH.)

We report a transition metal dichalcogenides-PtSe2 Q-switched single-mode fiber laser operating at 2783.2 nm with a nearly watt-level average output power. We made a PtSe2 coated highly reflective gold mirror to serve as a saturable absorber mirror. The modulation depth, saturable intensity and non-saturable loss of our PtSe2 sample were measured to be 10.2%, 0.093 GW/cm2 and 37.71%, respectively. By incorporating the as-prepared saturable absorber mirror in a single-mode Er3+-doped zirconium fluoride fiber laser, stable Q-switched laser pulses were obtained with a maximum average power of 932.7 mW. The pulse duration and repetition rate were $1.04 ~\mu \text{s}$ and 93.10 kHz, respectively. The corresponding pulse energy was $10.02 ~\mu \text{J}$ and the slope efficiency was 18.1%. By employing a plane ruled grating in the resonator, we also investigated the operating wavelength range of the PtSe2-coated mirror. A continuously wavelength-tunable Q-switched laser was obtained from 2733.0 nm to 2803.0 nm. To the best of our knowledge, this is the first demonstration of PtSe2 working as a saturable absorber for the 2.73- $2.80 ~\mu \text{m}$ waveband, and the Q-switched laser presents threefold and twofold increase in output power and pulse energy, respectively, over previously reported values achieved from ~3- $\mu \text{m}$ single-mode Q-switched fiber lasers enabled by two-dimensional materials. The results indicate that PtSe2 is an excellent wideband optical switch for high-power broadband mid-infrared laser pulses generation. [ABSTRACT FROM AUTHOR]

Lossy mode resonance (LMR) sensors not only support transverse magnetic mode (TM) but also respond to transverse electric (TE) polarization, which has the advantage over traditional surface plasmon resonance sensing supporting only a single TM polarization. We theoretically propose an LMR sensor that can detect the refractive index (RI) changes based on the Kretschmann configuration with PtSe2 material. The refractive index parameter of PtSe2 film is fitted through experimental measurements, and the performance of LMR sensor with PtSe2 is theoretically calculated. The figure of merit (FOM) of the sensor performance has been significantly improved, and the maximum FOM with 626 RIU−1 has been acquired. [ABSTRACT FROM AUTHOR]

1T phase of transition metal dichalcogenides (TMDCs) formed by group 10 transition metals (e.g. Pt, Pd) have attracted increasing interests due to their novel properties and potential device applications. Synthesis of large scale thin films with controlled phase is critical especially considering that these materials have relatively strong interlayer interaction and are difficult to exfoliate. Here we report the growth of centimeter-scale PtTe, 1T-PtTe2 and 1T-PtSe2 films via direct deposition of Pt metals followed by tellurization or selenization. We find that by controlling the Te flux, a hitherto-unexplored PtTe phase can also be obtained, which can be further tuned into PtTe2 by high temperature annealing under Te flux. These films with different thickness can be grown on a wide range of substrates, including NaCl which can be further dissolved to obtain free-standing PtTe2 or PtSe2 films. Moreover, a systematic thickness dependent resistivity and Hall conductivity measurements show that distinguished from the semiconducting PtSe2 with hole carriers, PtTe2 and PtTe films are metallic. Our work opens new opportunities for investigating the physical properties and potential applications of group 10 TMDC films and the new monochalcogenide PtTe film. [ABSTRACT FROM AUTHOR]

With the unique properties, layered transition metal dichalcogenide (TMD) and its heterostructures exhibit great potential for applications in electronics. The electrical performance, e.g., contact barrier and resistance to electrodes, of TMD heterostructure devices can be significantly tailored by employing the functional layers, called interlayer engineering. At the interface between different TMD layers, the dangling-bond states normally exist and act as traps against charge carrier flow. In this study, we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states, as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure. The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface, as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations. The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures. Thus, this technique provides an effective way for optimizing the interface contact, the crucial issue exists in two-dimensional electronic community. [ABSTRACT FROM AUTHOR]

In this study, we report the successful synthesis of few-layer parallel PtSe 2 ribbons on an Au foil employing a surface melting strategy via the chemical vapor deposition growth method at 650 °C. The controlled formation of parallel ribbons was directed by the Au steps generated through antimony treatment. These ribbons exhibit an average length of exceeding 100 μ m and a width of approximately 100 nm across a substantial area. Electrocatalysis measurements showcase the catalytic performance of PtSe 2 ribbons grown on Au foil, which can be further augmented through subsequent oxidation treatment. This investigation introduces an effective growth method for few-layer ribbons at low temperatures and broadens the scope of employing the substrate-guided strategies for the synthesis of one-dimensional materials. Additionally, it underscores the potential of PtSe 2 ribbons as an electrocatalyst for hydrogen evolution., (© 2024 IOP Publishing Ltd.)

Electronic devices employing two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenide (TMD) layers as semiconducting channels often exhibit limited performance (e.g., low carrier mobility), in part, due to their high contact resistances caused by interfacing non-vdW three-dimensional (3D) metal electrodes. Herein, we report that this intrinsic contact issue can be efficiently mitigated by forming the 2D/2D in-plane junctions of 2D semiconductor channels seamlessly interfaced with 2D metal electrodes. For this, we demonstrated the selectively patterned conversion of semiconducting 2D PtSe 2 (channels) to metallic 2D PtTe 2 (electrodes) layers by employing a wafer-scale low-temperature chemical vapor deposition (CVD) process. We investigated a variety of field-effect transistors (FETs) employing wafer-scale CVD-2D PtSe 2 /2D PtTe 2 heterolayers and identified that silicon dioxide (SiO 2 ) top-gated FETs exhibited an extremely high hole mobility of ∼120 cm 2 V -1 s -1 at room temperature, significantly surpassing performances with previous wafer-scale 2D PtSe 2 -based FETs. The low-temperature nature of the CVD method further allowed for the direct fabrication of wafer-scale arrays of 2D PtSe 2 /2D PtTe 2 heterolayers on polyamide (PI) substrates, which intrinsically displayed optical pulse-induced artificial synaptic behaviors. This study is believed to vastly broaden the applicability of 2D TMD layers for next-generation, high-performance electronic devices with unconventional functionalities.

We report on a wet chemistry method used to grow PtSe2 nanosheets followed by thermal annealing. The SEM and TEM analysis confirms the formation of PtSe2 nanosheets. Furthermore, XRD, Raman, XPS and SAED patterns were used to analyze the crystal structure and to confirm the formation of the PtSe2 phase. The temperature-dependent Raman spectroscopy investigations were carried out on PtSe2 nanosheets deposited on Si substrates in the temperature range 100–506 K. The shifts in Raman active Eg and A1g modes as a function of temperature were monitored. The temperature coefficient for both modes was calculated and was found to match well with the reported 2D transition metal dichalcogenides. A PtSe2 nanosheet-based sensor device was tested for its applicability as a humidity sensor and photodetector. The humidity sensor based on PtSe2 nanosheets showed an excellent recovery time of ≈5 s, indicating the great potential of PtSe2 for future sensor devices.

Platinum diselenide (PtSe2) is a promising transition metal dichalcogenide (TMDC) material with unique properties. It is necessary to find a controllable fabrication method to bridge PtSe2 with other two-dimensional (2D) materials for practical applications, which has rarely been reported so far. Here, we report that the selenization of Pt(111) can be suppressed to form a Se intercalated layer, instead of a PtSe2 monolayer, by inducing confined conditions with a precoating of graphene. Experiments with graphene-island samples demonstrate that the monolayer PtSe2 can be controllably fabricated only on the bare Pt surface, while the Se intercalated layer is formed underneath graphene, as verified by atomic-resolution observations with scanning transmission electron microscopy (STEM) and scanning tunneling microscopy (STM). In addition, the orientation of the graphene island shows a negligible influence on the Se intercalated layer induced by the graphene coating. By extending the application of 2D confined reactions, this work provides a new method to control the fabrication and pattern 2D materials during the fabrication process. [ABSTRACT FROM AUTHOR]

Here, an optically pumped terahertz (THz) modulator based on the novel transition metal dichalcogenide (TMD) material platinum diselenide (PtSe2) is demonstrated. The nanostructured PtSe2 thin films are formed by direct selenization of the sputtered platinum film on a high‐resistivity silicon substrate. Raman spectroscopy, scanning electron microscopy, and high‐resolution transmission electron microscopy confirm the formation of polycrystalline PtSe2 nanostructures. The transmission measurements reveal the modulation of the THz waves in the wide frequency range of 0.1–1 THz. The modulation depth of 32.7% is achieved under low pumping laser power of 1 W cm−2. The numerical analysis based on the finite difference time domain method is in good agreement with the experimentally obtained results. Further, the simulation results manifest that higher modulation depth can be achieved with the utilization of higher laser power. This work provides a path for the application of TMD materials like PtSe2 in the development of THz tunable devices such as modulators, polarizers, filters. [ABSTRACT FROM AUTHOR]

PtSe2 as a novel TMDCs material is used to modify the traditional SPR biosensors to improve the performance. On this basis, this research proposes a metal-Si-metal waveguide structure to further improve the performance of the biosensor. In this study, we not only studied the effects of waveguide structures containing different metals on the performance of biosensor, but also discussed the performance change of the biosensor with the change of PtSe2 thickness. After the final optimization, a BK7-Au-Si-Au-PtSe2 (2 nm) biosensor structure achieved the highest sensitivity of 193.8°/RIU. This work provides a new development idea for the study of SPR biosensors with waveguide structures in the future.

Two‐dimensional (2D) PtSe2 shows the most prominent layer‐dependent electrical properties among various 2D materials and high catalytic activity for hydrogen evolution reaction (HER), and therefore, it is an ideal material for exploring the structure–activity correlations in 2D systems. Here, starting with the synthesis of single‐crystalline 2D PtSe2 with a controlled number of layers and probing the HER catalytic activity of individual flakes in micro electrochemical cells, we investigated the layer‐dependent HER catalytic activity of 2D PtSe2 from both theoretical and experimental perspectives. We clearly demonstrated how the number of layers affects the number of active sites, the electronic structures, and electrical properties of 2D PtSe2 flakes and thus alters their catalytic performance for HER. Our results also highlight the importance of efficient electron transfer in achieving optimum activity for ultrathin electrocatalysts. Our studies greatly enrich our understanding of the structure–activity correlations for 2D catalysts and provide new insight for the design and synthesis of ultrathin catalysts with high activity. [ABSTRACT FROM AUTHOR]

We fabricated PtSe 2 /n-type GaN heterojunction diode by transferring a large-scale grown two-dimensional (2D) PtSe 2 layered film onto a 3D GaN substrate. The PtSe 2 film transferred onto GaN was ∼5.84-nm thick and had 11 layers with interlayer spacing of 0.52 nm. An exploration of the temperature-dependence of the current–voltage (I – V) characteristics of the PtSe 2 /n-type GaN heterojunction in the range 125–400 K revealed a strong dependency of the ideality factor and barrier height on measurement temperature. This indicates a presence of low- and high-barrier-height patches resembling barrier inhomogeneities along the interface. A barrier inhomogeneity analysis with a consideration for the Gaussian barrier heights distribution demonstrated the existence of a double Gaussian barrier distribution having a mean barrier height of 0.97 and 1.41 eV in low- and high-temperature regimes, respectively. An examination of the temperature-dependency of reverse leakage current indicated the dominance of variable-range hopping conduction in lower temperature region (<225 K) and Poole–Frenkel emission mechanism in higher temperature region (>250 K). The interface state density N ss of the PtSe 2 /n-type GaN heterojunction determined from the capacitance method was lesser than that attained from the forward I – V characteristics that can be accredited to the inhomogeneous spreading of the N ss. • ➢Fabricated PtSe 2 /n-GaN 2D/3D hybrid heterojunction by PtSe 2 layer transfer on GaN. • A 5.84-nm-thick PtSe 2 film having ∼11 layers were formed on GaN. • Current-voltage properties of Au/PtSe 2 /n-GaN heterojunction rely strongly on temperature. • Barrier inhomogeneities exists at interface with a double Gaussian barrier distribution. • Variable-range hoping and Poole-Frenkel emission dominates reverse current transport at low and high temperature. [ABSTRACT FROM AUTHOR]

As a topological Dirac semimetal with controllable spin-orbit coupling and conductivity, PtSe 2 , a transition-metal dichalcogenide, is a promising material for several applications, from optoelectrics to sensors. However, its potential for spintronics applications has yet to be explored. In this work, we demonstrate that the PtSe 2 /Ni 80 Fe 20 heterostructure can generate large damping-like current-induced spin-orbit torques (SOT), despite the absence of spin-splitting in bulk PtSe 2 . The efficiency of charge-to-spin conversion is found to be -0.1 ± 0.02 nm -1 in PtSe 2 /Ni 80 Fe 20 , which is 3 times that of the control sample, Ni 80 Fe 20 /Pt. Our band structure calculations show that the SOT due to PtSe 2 arises from an unexpectedly large spin splitting in the interfacial region of PtSe 2 introduced by the proximity magnetic field of the Ni 80 Fe 20 layer. Our results open up the possibilities of using large-area PtSe 2 for energy-efficient nanoscale devices by utilizing proximity-induced SOT.