Monolayer PtSe2 Research Articles

Exploration of Zr-doped PtSe2 monolayer for sensing C2H2 and C2H4 in oil-immersed transformers of HVDC converter station: A first-principles investigation

Using the first-principles theory, this work purposes Zr-doped PtSe2 (Zr-PtSe2) monolayer as a potential sensing material upon two typical dissolved gases (C2H2 and C2H4), in order to evaluate the operation status of the oil-immersed transformers. Zr-doping on the pristine PtSe2 monolayer is firstly analyzed, yielding the formation energy of −3.12 eV. The Zr-PtSe2 monolayer conducts chemisorption upon C2H2 and C2H4 with the adsorption energy of −1.40 and −1.02 eV, respectively. The electronic property analysis of the gas adsorbed systems reveal the much higher sensing response upon C2H2 molecule, and the recovery property analysis uncovers the reusability for the purposed material. Moreover, the work function is also analyzed to explore the sensing potential of Zr-PtSe2 monolayer based on its change after gas adsorption. The findings pave the way to explore the PtSe2-based material as gas sensors, providing informative guidance for gas sensing material exploration in the electrical engineering.

Evolutionary Pathways of T-Phase Transition Metal Dichalcogenides: A Comprehensive Study of PtxSey Clusters.

Understanding the transition from nonplanar to planar clusters is crucial for the controllable synthesis of transition metal dichalcogenide (TMDC) monolayers. Using PtSe2 as a model, we investigate how the chemical environment influences the nucleation and growth stages of monolayer PtSe2 through structure searching and first-principles calculations. We established a comprehensive database of platinum selenide clusters (PtxSey, 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 PtxSey clusters, representing an evolutionary route for PtSe2 growth. Clusters such as PtSe6, Pt2Se9, Pt3Se10, and Pt7Se10 in Pt-rich environments, as well as Pt2Se15 and Pt10Se32 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. PtSe4 and PtSe6 are found to be highly stable under most experimentally achievable chemical potential conditions and may serve as dominant precursors during PtSe2 growth. This work advances our understanding of the nucleation processes of PtSe2 and other T-phase TMDC materials.

Electronic and magnetic property of vacancy defects in monolayer PtSe2: A first-principles study

In this paper, we investigate the effect of Pt vacancy, Fe and Mn atoms on the magnetic properties of PtSe2 based on first principles. We find that the transition metal can successfully induce the magnetic properties of PtSe2 with a single atom of Fe or Mn and two atoms of Fe, Mn doped. On the basis of this study, the magnetic property of Pt vacancy on pure PtSe2, Mn doped PtSe2, (Fe, Mn) co-doped PtSe2 are investigated, respectively, and find that the introduction of Pt vacancy increase the magnetic moments of the VPt-PtSe2 and (Mn, VPt)-PtSe2 system, whereas the magnetic moments of the (Fe, Mn, VPt) system does not change greatly, but the introduction of Pt vacancy make the ΔE of the (Fe, Mn, VPt) system −206meV, which become more stable ferromagnetic material compared to (Fe, Mn)-PtSe2. We offer valuable insights for designing PtSe2-based spintronics and nanoelectronics.

Dual-photoconductivity in monolayer PtSe2 ribbons

Dual-photoconductivity in monolayer PtSe2 ribbons

SiC/PtSe2 van der Waals heterostructure: A high-efficiency direct Z-scheme photocatalyst for overall water splitting predicted from first-principles study

The discovery of effective photocatalytic substances is crucial in reducing energy shortages and ecological contamination. This research involves creating SiC/PtSe2 van der Waals heterostructure with both SiC and PtSe2 monolayers, employing first-principles calculations for comprehensive theoretical analysis of their structural stability, electronic characteristics, optical features, Bader charge, and solar-to-hydrogen (STH) efficiency. Findings indicate that the SiC/PtSe2 heterostructure is a semiconductor with an indirect bandgap of 1.52 eV and a direct Z-scheme charge transfer path, facilitating more efficient segregation of photogenerated electron-hole pairs. The Bader charge indicates that the SiC layer accumulates positive charges and the PtSe2 layer accumulates negative charges, constituting a built-in electric field pointing from the SiC side to the PtSe2 side at the interface region, which can impede the complexation of the photogenerated electron-hole pairs. Furthermore, the SiC/PtSe2 heterostructure exhibits excellent optical absorption properties across both the ultraviolet and visible spectra, coupled with an exceptionally high STH efficiency of 34.7 %, significantly enhancing solar energy utilization. Ultimately, the Gibbs free energy calculations reveal the significant catalytic efficiency of the SiC/PtSe2 heterostructure for redox reactions. Based on these results, the SiC/PtSe2 heterostructure is a direct Z-scheme photocatalyst for overall water splitting.

Inducing feature-rich electronic and magnetic properties in PtSe2 monolayer via doping with TMXn clusters (TM = Mn and Fe; X = N and P; n = 3 and 6): A first-principles study

In this work, doping with TMXn (TM = Mn and Fe; X = N and P, n = 3 and 6) clusters is proposed to modify the electronic and magnetic properties of PtSe2 monolayer. Pristine PtSe2 monolayer is a non-magnetic two-dimensional (2D) semiconductor material with indirect band gap of 1.40(2.01) eV obtained from PBE(HSE06)-based calculations. PtSe3-type multivacancies lead to the monolayer magnetization with total magnetic moment of 0.54 μB, where Pt and Se atoms around defect sites produce mainly the system magnetism. In contrast, no magnetism is induced by PtSe6-type multivacancies. The substitutional incorporation of TMXn clusters magnetizes significantly PtSe2 monolayer, where both TM and X atoms originate mainly the magnetic properties. Depending on the spin orientation in the clusters, total magnetic moments between 0.00 and 8.00 μB are obtained. All the doped DTMXn systems exhibit strong spin polarization around the Fermi level, which is derived mainly from the outermost TM-3d, N-2p, and P-3p orbitals. Consequently, either half-metallicity or magnetic semiconductor behavior can be induced, depending on the nature of TMXn cluster. Further, the Bader analysis indicates that TMNn clusters act as charge gainers due to the more electronegative nature of N atoms in comparison with Se atoms, meanwhile TMPn clusters transfer charge to the host PtSe2 monolayer. Our study may introduce the cluster doping in PtSe2 monolayer as efficient method to create new highly spin-polarized 2D materials towards spintronic applications.

Adsorption and gas sensing properties of Pdn(n=1–3) cluster-modified PtSe2 on transformer fault characterizing gases under biaxial strain and electric field

In this study, the adsorption behavior of three DGA gases (C2H2, C2H4, and CO) on monolayers of PtSe2 doped with metal clusters Pdn(n=1–3) was investigated using density-functional theory (DFT). The critical influence of the Pd clusters on the sensitivity of PtSe2 gas is revealed by in-depth analysis of the geometrical structure of the adsorption system, DCD, ELF, DOS and band gap. The results show that the detection performance of intrinsic PtSe2 monolayer is poor. However, the doping of Pdn(n=1–3) fundamentally changes the adsorption behavior of PtSe2 on C2H2 and C2H4 from an adsorptive to an exothermic reaction, and endows it with excellent adsorption, desorption, and gas sensitivity properties. In addition, the introduction of external electric field and biaxial strain can significantly change the charge transfer, band gap, and adsorption energy of each adsorption system, which suggests that the Pdn(n=1–3)-PtSe2 monolayer has excellent tunability and can be strain-modulated for gas detection.

Oxygen intercalation in 2D layered PtSe2 for tunable bandgap infrared photoelectric materials

Infrared materials play a pivotal role in driving societal advancement across various domains. Bilayer PtSe2 with bandgap of 0.2 eV is an ideal material for infrared applications. However, the inherent limitation of the untunable bandgap in bilayer PtSe2 restricts its utility, particularly in the context of state-of-the-art two-color infrared detectors. Therefore, by introduction of quantum confinement effect, PtSe2[O]y superlattice was constructed via intercalating O atoms into interlayer space of PtSe2, and kinetic stability was confirmed by ab initio molecular dynamics. Considering van der Waals interactions of interlayer, PtSe2[O]y superlattice can be exfoliated into few-layer PtSe2[O]y. By employing density functional theory, optical and electrical properties of PtSe2[O]y superlattice and few-layer PtSe2[O]y were calculated. Tunable bandgaps were achieved by manipulating the O composition y, ranging from 0 eV to 0.21 eV (covering wavelengths > 5.9 μm) for the PtSe2[O]y superlattice and from 1.12 eV to 0.15 eV (covering wavelengths from 1.1 μm to 8.3 μm) for monolayer PtSe2[O]y. Considering the continuously tunable bandgap covering from near-infrared to mid-infrared absorption spectrum, PtSe2[O]y could be a promising candidate with a wide-application in the field of infrared photoelectric materials.

Electronic structure of rare-earth erbium-doped platinum diselenide: A density functional theory study

The effect of rare-earth erbium (Er) doping on the electronic structure of platinum diselenide (PtSe2) as a 2D transition metal dichalcogenide was studied using density functional theory (DFT). Our DFT calculations showed that Er dopant in PtSe2 led to the formation of additional states in the valence and conduction bands, and new localized states within the band gap of PtSe2. The orbital-resolved density of states revealed that the 4f orbitals of the dopant Er atom strongly impact the electronic structure of the monolayer PtSe2 and induce spin-polarized localized states. Simultaneously, in addition to a significant increase in the PtSe2 surface energy (52-fold) due to Er doping (from 7.94 × 10−5 to 4.16 × 10−3 eV/Å2), the formation energy of the Er-doped PtSe2 (−328.72 kJ/mol) compared to the pristine PtSe2 (−326.52 kJ/mol) indicates that Er doping has made the PtSe2 system thermodynamically more stable. The results of this study can be used as a guide to design devices for optoelectronic applications such as sensors.

First Principles Calculation of Gas Sensitive Properties of Pd3‐Modified Monolayer PtSe2 to SF6 Decomposition Products

Based on density functional theory (DFT), the effect of Pd3 cluster modification on the surface properties of PtSe2 monolayer and the gas sensitive detection performance of PtSe2/Pd3–PtSe2 on sulfur hexafluoride (SF6) decomposition is studied, in terms of the adsorption energy, density of states (DOS), and sensing characteristic. It is found that that the Pd3 cluster exhibit stable modified structure on monolayer PtSe2, the adsorption capacity of Pd3–PtSe2 monolayer is the highest, significantly improves the surface activity and sensing performance of PtSe2 monolayer. Further, the large charge transfer, bandgap, and conductivity changes indicate that the monolayer Pd3–PtSe2 has strong chemical interaction and high sensitivity to SO2, H2S, and SO2F2 gas molecules. Pd3–PtSe2 can be used as a potential candidate for gas sensors. Finally, the sensing performance analysis of the system shows that the recovery time of Pd3–PtSe2 for SO2F2 is only 10.7 s, which can be repeated for a long time. These analyses illustrate the potential application of Pd3–PtSe2 in the detection and removal of harmful gases in gas insulated switch‐gear (GIS). The calculations may provide new insights for researchers to explore gas‐sensitive materials based on PtSe2.

Rational design of single transition-metal atoms anchored on a PtSe2 monolayer as bifunctional OER/ORR electrocatalysts: a defect chemistry and machine learning study

Design of low overpotential bifunctional OER/ORR electrocatalysts by adjusting the charge states of TM@PtSe2 is a new effective method.

Enhanced broadband light absorption of ultrathin PtSe2 in metal–insulator–metal structure

The enhancement of light absorption in an ultrathin two-dimensional material is critical for its optoelectronic and photonic applications. In this work, we investigated the enhanced light absorption of layered PtSe2 by engineering the optical impedance and the attenuation of the PtSe2-based metal–insulator–metal (MIM) absorber. For a monolayer PtSe2-based MIM absorber, the undesirable impedance mismatch can be compensated for using the top patterned metal array in the MIM structure to achieve near-perfect absorption (99.95%), and the absorption of monolayer PtSe2 is enhanced by 8.6 times in the visible spectra. For a few-layer PtSe2 MIM absorber, the self-impedance of the PtSe2 layer becomes an important factor in modulating the optical absorption and the PtSe2-based absorbers show excellent features with broadband absorption, insensitive to the incident angle and polarization. Our results improve the viability of the PtSe2-based optoelectronic and photonic devices and shed light on the design of absorbers with hybrid 2D materials.

A van der Waals Heterostructure with an Electronically Textured Moiré Pattern: PtSe2/PtTe2

The interlayer interaction in Pt-dichalcogenides strongly affects their electronic structures. The modulations of the interlayer atom-coordination in vertical heterostructures based on these materials are expected to laterally modify these interlayer interactions and thus provide an opportunity to texture the electronic structure. To determine the effects of local variation of the interlayer atom coordination on the electronic structure of PtSe2, van der Waals heterostructures of PtSe2 and PtTe2 have been synthesized by molecular beam epitaxy. The heterostructure forms a coincidence lattice with 13 unit cells of PtSe2 matching 12 unit cells of PtTe2, forming a moiré superstructure. The interaction with PtTe2 reduces the band gap of PtSe2 monolayers from 1.8 eV to 0.5 eV. While the band gap is uniform across the moiré unit cell, scanning tunneling spectroscopy and dI/dV mapping identify gap states that are localized within certain regions of the moiré unit cell. Deep states associated with chalcogen pz-orbitals at binding energies of ∼ -2 eV also exhibit lateral variation within the moiré unit cell, indicative of varying interlayer chalcogen interactions. Density functional theory calculations indicate that local variations in atom coordination in the moiré unit cell cause variations in the charge transfer from PtTe2 to PtSe2, thus affecting the value of the interface dipole. Experimentally this is confirmed by measuring the local work function by field emission resonance spectroscopy, which reveals a large work function modulation of ∼0.5 eV within the moiré structure. These results show that the local coordination variation of the chalcogen atoms in the PtSe2/PtTe2 van der Waals heterostructure induces a nanoscale electronic structure texture in PtSe2.

Multi-functional application potential of Ruddlesden–Popper perovskite-based heterostructure PtSe2/Cs2PbI4 with tunable electronic properties

Heterogeneous stacking based on two-dimensional Ruddlesden–Popper (RP) perovskite is a desired strategy for the reasonable combination of stability and efficiency. Constructing heterostructures with tunable optoelectronic properties further provide opportunities to design multi-functional devices. Herein, we present a first-principle research to investigate the geometric and electronic structures of RP perovskite heterostructure PtSe2/Cs2PbI4 and its tunable electronic properties induced by thickness modulation and external strains. The results indicate that the heterostructure based on Cs2PbI4 monolayer and PtSe2 monolayer has a type-II band alignment, which is suitable for the photovoltaic applications. With the layer number of PtSe2 in heterostructure increases from monolayer to bilayer, the band alignment of PtSe2/Cs2PbI4 heterostructure can switch from type-II to type-I, which is beneficial for the luminescence device applications. However, when the thickness of PtSe2 in heterostructure further increases to trilayer, the heterostructure exhibits metallic characteristic with a p-type Schottky barrier. In addition, we find the strain engineering is an effective knob in tuning the electronic properties of PtSe2/Cs2PbI4 heterostructures with different thickness. These findings reveal the potential of PtSe2/Cs2PbI4 heterostructure as a tunable hybrid material with substantial prospect in multi-functional applications.

Interfacial electronic properties between PtSe2 and 2D metal electrodes: a first-principles simulation.

Monolayer (ML) PtSe2 is a two-dimensional (2D) semiconductor with a modest band gap and high carrier mobility, and it is a promising 2D material for electronic devices. Finding suitable metal electrodes is a key factor in fabricating high-performance PtSe2 field effect transistors (FETs). In this study, a series of 2D metals, transition metal dichalcogenides (NbSe2, TaS2), borophene, and MXenes (V2C(OH)2, V2CF2, Nb2C(OH)2, Nb2CF2, Nb2CO2, Hf2C(OH)2, Hf2CF2) were used as electrodes for FET fabrication. The interfacial electronic properties of electrodes and PtSe2 were studied in both the vertical and lateral directions using the ab initio method. In the vertical direction, PtSe2 formed ohmic contacts with most of the 2D metals except for Nb2CF2 and Hf2CF2. Specifically, in the cases of Nb2CF2 and Hf2CF2, p- and n-type Schottky contacts were formed with Schottky barrier heights (SBHs) of 0.48 eV and 0.02 eV, respectively. In the lateral direction, PtSe2 with contacting Hf2CF2 and V2C(OH)2 electrodes formed n-type Schottky contacts with SBHs of 0.14 eV and 0.09 eV, respectively. In the cases of TaS2 and Nb2CF2 electrodes, p-type Schottky contacts with SBHs of 0.35 eV and 0.29 eV, respectively, were formed. Moreover, n-type ohmic contacts were observed when Hf2C(OH)2 and Nb2C(OH)2 electrodes were applied, and p-type ohmic contacts were formed when borophene, NbSe2, Nb2CO2, and V2CF2 electrodes were used. This work reports a systematic investigation of ML PtSe2-2D metal interfaces and serves as a practical guide for selecting electrode materials for PtSe2 FETs.

Electrical field and biaxial strain tunable electronic properties of the PtSe2/Hf2CO2 heterostructure.

The structure and electronic properties of two-dimensional vertical van der Waals PtSe2/Hf2CO2 heterostructure have been investigated based on first-principles calculations. The results show that the PtSe2 and Hf2CO2 monolayers form a type-I heterostructure with both the conduction band minimum (CBM) and valence band maximum (VBM) located at the Hf2CO2 layer. The electronic properties of PtSe2/Hf2CO2 heterostructure can be effectively adjusted by applying external electric field or biaxial strain. The transition in band alignment from type-I to type-II can be manipulated by controlling the strength and direction of the electric field. Additionally, the transition from type-I to type-II have also taken place under the strains, and the band gap of the PtSe2/Hf2CO2 heterostructure decreases with increasing the compressive or tensible strain. Under a strong strain of -8%, the PtSe2/Hf2CO2 heterostructure can transform from semiconductor to metal. These findings provide a promising method to tune the electronic properties of PtSe2/Hf2CO2 heterostructure and design a new vdW heterostructure in the applications for electronic and optoelectronic devices.

PtSe2/SnS2 heterostructure as a direct Z-scheme photocatalyst for water decomposition

The direct Z-scheme heterostructure has attracted much attention due to its strong photocatalytic ability. In the present work, we use density functional theory to explore the electronic and optical properties and photocatalytic mechanism of PtSe2/SnS2 heterostructure. Compared with PtSe2 and SnS2 monolayers, PtSe2/SnS2 heterostructure has smaller band gap and better light absorption capacity. The results of band calculation show that the heterostructure form a band arrangement of type-II. Further work function calculations indicate that the direction of the built-in electric field is PtSe2 to SnS2, indicating the charge transfer mechanism is Z-scheme. In the water decomposition reaction, the free energy calculation results show that water decomposition reaction can occur spontaneously under light. Therefore, PtSe2/SnS2 heterostructure can be used as a potential Z-scheme photocatalyst for hydrogen and oxygen production.

CuO-Modified PtSe2 Monolayer as a Promising Sensing Candidate toward C2H2 and C2H4 in Oil-Immersed Transformers: A Density Functional Theory Study.

This work using the density functional theory simulates the strong potential of the CuO-decorated PtSe2 (CuO-PtSe2) monolayer as a recycle use C2H2 and C2H4 sensor in order to realize the arc discharge monitoring based on the nano-sensing method. Results indicate that CuO decoration causes strong n-type doping for the PtSe2 monolayer with a binding force (E b) of -2.49 eV, and the CuO-PtSe2 monolayer exhibits strong chemisorption and electron-accepting properties in the two gas systems, with the adsorption energy (E ad) and charge transfer (Q T) obtained as -1.19 eV and 0.040 e for the C2H2 system and as -1.24 eV and 0.011 e for the C2H4 system, respectively. The density of states reveals the deformed electronic property of the CuO-PtSe2 monolayer in gas adsorptions, and its sensing mechanism based on the change of electrical conductivity and the work function are uncovered. This work sheds light on the metal-oxide-decorated transition-metal dichalcogenides for gas sensor applications and would provide the guidance to explore novel sensing materials in many other fields as well.

Defect-Induced Ultrafast Nonadiabatic Electron-Hole Recombination Process in PtSe2 Monolayer.

Defects are inevitable in two-dimensional materials due to the growth condition, which results in many unexpected changes in materials' properties. Here, we have mainly discussed the nonradiative recombination dynamics of PtSe2 monolayer without/with native point defects. Based on first-principles calculations, a shallow p-type defect state is introduced by a Se antisite, and three n-type defect states with a double-degenerate shallow defect state and a deep defect state are introduced by a Se vacancy. Significantly, these defect states couple strongly to the pristine valence band maximum and lead to the enhancement of the in-plane vibrational Eg mode. Both factors appreciably increase the nonadiabatic coupling, accelerating the electron-hole recombination process. An explanation of PtSe2-based photodetectors with the slow response, compared to conventional devices, is provided by studying this nonradiative transitions process.

Interlayer Coupling Induced Phonon-Glass–Electron-Crystal Behavior in van der Waals Heterostructure PtSe2/γ-GeSe

We report the electronic band structure and interlayer coupling induced phonon-glass–electron-crystal behavior in the van der Waals heterostructure PtSe2/γ-GeSe. The heterostructure is dynamically stable and possesses an indirect band gap of 0.63 eV (at the Heyd–Scuseria–Ernzerhof functional level) with type II band alignment. A low conduction band offset of 0.20 eV compared to the valence band offset of 0.92 eV suggests fluent electrons drive from γ-GeSe to PtSe2. Interlayer coupling induced strong phonon coupling and a unique “avoided crossing” feature between longitudinal acoustic and low-lying optical phonon modes between K and Γ points. Significant suppression of acoustic phonon modes and giant phonon scattering rates (a maximum value of 73.76 ps–1) results in a low lattice thermal conductivity of 1.20 W/(m·K) at 300 K after enforcing the mandatory rotational invariance condition. The calculated lattice thermal conductivity is 14-fold smaller than that of monolayer PtSe2 (16.97 W/(m·K)). The lattice thermal conductivity upsurges by 24% as the out-of-plane acoustic phonon dispersion undergoes linear dispersion, indicating the importance of pure quadratic flexural phonon dispersion. Our results disclose a strategy for having the phonon-glass–electron-crystal character in van der Waals heterostructures.