A two-dimensional MoS2/C3N broken-gap heterostructure,a first principles study

van der Waals (vdW) heterojunctions are of interest in two-dimensional electronic and optoelectronic devices. In this work, first-principles calculations were used to study the atomic and electronic properties of the MoS₂/C₃N vdW heterojunction. The results show that there is no overlap of the band gaps for the MoS₂ and C₃N monolayers in the heterojunction, indicating the MoS₂/C₃N vdW heterostructure has a type III alignment. The MoS₂/C₃N vdW heterostructure is a broken-gap heterojunction. The effects of biaxial strain and external electric field on the band structure of the vdW heterostructure were also investigated. The alignment type cannot be changed, but the band overlap can be tuned. The present work reveals that the MoS₂/C₃N heterostructures are quite favorable for applications in tunneling devices based on the broken-gap heterostructures.

van der Waals (vdW) heterojunctions are of interest in two-dimensional electronic and optoelectronic devices.     

Electronic structure,optoelectronic properties and enhanced photocatalytic response of GaN–GeC van der Waals heterostructures: a first principles study

In this work, we systematically studied the electronic structure and optical characteristics of van der Waals (vdW) heterostructure composed of a single layer of GaN and GeC using first principles calculations. The GaN–GeC vdW heterostructure exhibits indirect band gap semiconductor properties and possesses type-II energy band arrangement, which will help the separation of photogenerated carriers and extend their lifetime. In addition, the band edge positions of the GaN–GeC heterostructure meet both the requirements of water oxidation and reduction energy, indicating that the photocatalysts have the potential for water decomposition. The GaN–GeC heterostructure shows obvious absorption peaks in the visible region, leading to the efficient use of solar energy. Tensile and compressive strains of up to 10% are also proposed. Tensile strain leads to an increase in the blue shift of optical absorption, whereas a red shift is observed in the case of the compressive strain. These fascinating characteristics make the GaN–GeC vdW heterostructure a highly effective photocatalyst for water splitting.

In this work, we systematically studied the electronic structure and optical characteristics of van der Waals (vdW) heterostructure composed of a single layer of GaN and GeC using first principles calculations.     

First principles study of electronic and optical properties and photocatalytic performance of GaN–SiS van der Waals heterostructure

The vertical stacking of two-dimensional materials via van der Waals (vdW) interaction is a promising technique for tailoring the physical properties and fabricating potential devices to be applied in the emerging fields of materials science and nanotechnology. The structural, electronic and optical properties and photocatalytic performance of a GaN–SiS vdW heterostructure were explored using first principles calculations. The most stable stacking configuration found energetically stable, possesses a direct staggered band gap, which is crucial for separating photogenerated charged carriers in different constituents and is efficacious for solar cells. Further, the charge transfer occurred from the SiS to GaN layer, indicating that SiS exhibits p-type doping in the GaN–SiS heterobilayer. Interestingly, a systematic red-shift was observed in the optical absorption spectra of the understudy heterobilayer system. Moreover, the conduction band edge and valence band edge of the monolayers and corresponding heterostructure were located above and below the standard redox potentials for photocatalytic water splitting, making these systems promising for water dissociation for hydrogen fuel production. The results provide a route to design the GaN–SiS vdW heterostructure for the practical realization of next-generation light detection and energy harvesting devices.

The two dimensional GaN–SiS van der Waals heterostructure is a promising candidate for optoelectronic and photocatalytic water splitting.     

Tunable spin-polarized band gap in Si2/NiI2 vdW heterostructure

Using density functional theory (DFT) calculations we investigate the structural and electronic properties of a heterogeneous van der Waals (vdW) structure consisting of silicene and NiI₂ single layers. We observe an interaction between the two layers with a net charge transfer from the ferromagnetic semiconductor NiI₂ to silicene, breaking the inversion symmetry of the silicene structure. However, the charges flow in opposite directions for the two spin channels, which leads to a vdW heterostructure with a spin-polarized band gap between the π and π* states. The band gap can be tuned by controlling the vertical distance between the layers. The features shown by this vdW heterostructure are new, and we believe that silicene on a NiI₂ layer can be used to construct heterostructures which have appropriate properties to be used in nanodevices where control of the spin-dependent carrier mobility is necessary and can be incorporated into silicon based electronics.

Using density functional theory (DFT) calculations we investigate the structural and electronic properties of a heterogeneous van der Waals (vdW) structure consisting of silicene and NiI₂ single layers.     

Adjusting the electronic properties and contact types of graphene/F-diamane-like C4F2 van der Waals heterostructure: a first principles study

Motivated by the successful exfoliation of two-dimensional F-diamane-like C₄F₂ monolayer and the superior properties of graphene-based vdW heterostructures, in this work, we perform a first principles study to investigate the atomic structure, electronic properties and contact types of the graphene/F-diamane-like C₄F₂ heterostructure. The graphene/C₄F₂ vdW heterostructure is structurally stable at room temperature. In the ground state, the graphene/C₄F₂ heterostructure forms n-type Schottky contact with a Schottky barrier height of 0.46/1.03 eV given by PBE/HSE06. The formation of the graphene/C₄F₂ heterostructure tends to decrease in the band gap of the semiconducting C₄F₂ layer, suggesting that such a heterostructure may have strong optical absorption. Furthermore, the electronic properties and contact types of the graphene/C₄F₂ heterostructure can be adjusted by applying an external electric field, which leads to the change in the Schottky barrier height and the transformation from Schottky to ohmic contact. Our findings reveal the potential of the graphene/C₄F₂ heterostructure as a tunable hybrid material with strong potential in electronic applications.

We perform a first principles study to investigate the atomic structure, electronic properties and contact types of the graphene/F-diamane-like C₄F₂ heterostructure.     

Strain-enhanced properties of van der Waals heterostructure based on blue phosphorus and g-GaN as a visible-light-driven photocatalyst for water splitting

Many strategies have been developed to overcome the critical obstacles of fast recombination of photogenerated charges and the limited ability of semiconductor photocatalysts to absorb visible light. Considering all the novel properties of monolayered g-GaN and blue phosphorus (BlueP) which were revealed in recent studies, first-principles calculations were used to systematically investigate the structural stability, electronic energy, band alignment, band bending, and charge difference in the heterostructure formed by these two layered materials. The g-GaN/BlueP heterostructure is constructed by van der Waals (vdW) forces, and it possess a staggered band structure which induces electron transformation because of the different Fermi levels of the two layered materials. By aligning the Fermi levels, an interfacial electric field is built and it causes band bending, which can promote effective separation of photoexcited holes and electrons; the band-bending phenomenon was also calculated according to density functional theory (DFT). Moreover, effects of in-plane strain on the tuned bandgap, energy, and band edge were investigated, and the results show that the optical-absorption performance in the visible-light range can be improved. The findings reported in this paper are expected to provide theoretical support for the use of the g-GaN/BlueP vdW heterostructure as a photocatalyst for water splitting.

Many strategies have been developed to overcome the critical obstacles of fast recombination of photogenerated charges and the limited ability of semiconductor photocatalysts to absorb visible light.     

Tunable electronic and optical properties of a BAs/As heterostructure by vertical strain and external electric field

Based on the first-principles method, we investigated the electronic properties of a BAs/arsenene (As) van der Waals (vdW) heterostructure and found that it has an intrinsic type-II band alignment with a direct band gap of 0.25 eV, which favors the separation of photogenerated electrons and holes. The band gap can be effectively modulated by applying vertical strain and external electric field, displaying a large alteration in the band gap via the strain and experiencing an indirect-to-direct band gap transition. Moreover, the band gap of the heterostructure varies almost linearly with external electric field, and the semiconductor-to-metal transition can be realized in the presence of a strong electric field. The calculated band alignment and optical absorption reveal that the BAs/As heterostructure could present an excellent light-harvesting performance. The absorption strength can be tuned mainly by interlayer coupling, while external electric field shows clear regulating effects on the absorption strength and absorption edge.

The CBM (VBM) of the heterostructure is mainly contributed by the BAs (arsenene), which will favor the separation of photogenerated electron–hole pairs.     

HfS2/MoTe2 vdW heterostructure: bandstructure and strain engineering based on first-principles calculation

In this study, a multilayered van der Waals (vdW) heterostructure, HfS₂/MoTe₂, was modeled and simulated using density functional theory (DFT). It was found that the multilayers (up to 7 layers) are typical indirect bandgap semiconductors with an indirect band gap varying from 0.35 eV to 0.51 eV. The maximum energy value of the valence band (VBM) and the minimum energy value of the conduction band (CBM) of the heterostructure were found to be dominated by the MoTe₂ layer and the HfS₂ layer, respectively, characterized as type-II band alignment, leading to potential photovoltaic applications. Optical spectra analysis also revealed that the materials have strong absorption coefficients in the visible and ultraviolet regions, which can be used in the detection of visible and ultraviolet light. Under an external strain perpendicular to the layer plane, the heterostructure exhibits a general transition from semiconductor to metal at a critical interlayer-distance of 2.54 Å. The carrier effective mass and optical properties of the heterostructures can also be modulated under external strain, indicating a good piezoelectric effect in the heterostructure.

In this study, a multilayered van der Waals (vdW) heterostructure, HfS₂/MoTe₂, was modeled and simulated using density functional theory (DFT).     

Enhanced nonlinear optical response of graphene-based nanoflake van der Waals heterostructures

The nonlinear optical properties of van der Waals bilayer heterostructures composed of graphene/h-BN and graphene/phosphorene nanoflakes are investigated using time-dependent density functional theory. Our calculated results show a significant enhancement of the first-hyperpolarizability value, β in heterostructures relative to the pristine nanoflakes at λ = 1064 nm. The calculated enhancement in optical nonlinearity mainly results from in-plane anisotropy induced by the interlayer electronic coupling between the adjacent nanoflake layers; a higher degree of anisotropy is induced by puckered phosphorene compared to atomically flat h-BN yielding χ⁽²⁾ value corresponding to the second harmonic generation of ∼50 pm V⁻¹ in the zigzag graphene/phosphorene bilayer heterostructure. The calculated results clearly show that graphene-based nanoflake heterostructures giving large NLO coefficients together with high electron mobility of these materials offer new opportunities as candidate materials of choice for next-generation photonics and integrated quantum technologies.

The nonlinear optical properties of van der Waals bilayer heterostructures composed of graphene/h-BN and graphene/phosphorene nanoflakes are investigated using time-dependent density functional theory.     

Van der Waals heterostructures of SiC and Janus MSSe (M = Mo,W) monolayers: a first principles study

Favorable stacking patterns of two models with alternative orders of chalcogen atoms in SiC-MSSe (M = Mo, W) vdW heterostructures are investigated using density functional theory calculations. Both model-I and model-II of the SiC-MSSe (M = Mo, W) vdW heterostructures show type-II band alignment, while the spin orbit coupling effect causes considerable Rashba spin splitting. Furthermore, the plane-average electrostatic potential is also calculated to investigate the potential drops across the heterostructure and work function. The imaginary part of the dielectric function reveals that the first optical transition is dominated by excitons with high absorption in the visible region for both heterostructures. Appropriate band alignments with standard water redox potentials enable the capability of these heterostructures to dissociate water into H⁺/H₂ and O₂/H₂O.

Using DFT calculations, we have investigated the electronic structure, Rashba effect, optical and photocatalytic performance of SiC-MSSe (M = Mo, W) van der Waals heterostructures with different stacking patterns of chalcogen atoms.     

Effects of electric field and strain engineering on the electronic properties,band alignment and enhanced optical properties of ZnO/Janus ZrSSe heterostructures

The formation of van der Waals heterostructures (vdWHs) have recently emerged as promising structures to make a variety of novel nanoelectronic and optoelectronic devices. Here, in this work, we investigate the structural, electronic and optical features of ZnO/ZrSSe vdWHs for different stacking patterns of ZnO/SeZrS and ZnO/SZrSe by employing first-principles calculations. Binding energy and ab initio molecular dynamics calculations are also employed to confirm the structural and thermal stability of the ZnO/ZrSSe vdWHs for both models. We find that in both stacking models, the ZnO and ZrSSe layers are bonded via weak vdW forces, leading to easy exfoliation of the layers. More interestingly, both the ZnO/SeZrS and ZnO/SZrSe vdWHs posses type-II band alignment, making them promising candidates for the use of photovoltaic devices because the photogenerated electrons–holes are separated at the interface. The ZnO/ZrSSe vdWHs for both models possess high performance absorption in the visible and near-infrared regions, revealing their use for acquiring efficient photocatalysts. Moreover, the band gap values and band alignments of the ZnO/ZrSSe for both models can be adjusted by an electric field as well as vertical strains. There is a transformation from semiconductor to metal under a negative electric field and tensile vertical strain. These findings demonstrate that ZnO/ZrSSe vdWHs are a promising option for optoelectronic and nanoelectronic applications.

Here, in this work, we investigate the structural, electronic and optical features of ZnO/ZrSSe vdWHs for different stacking patterns of ZnO/SeZrS and ZnO/SZrSe by employing first-principles calculations.     

Electronic structure and interface contact of two-dimensional van der Waals boron phosphide/Ga2SSe heterostructures

In this work, we systematically examine the electronic features and contact types of van der Waals heterostructures (vdWHs) combining single-layer boron phosphide (BP) and Janus Ga₂SSe using first-principles calculations. Owing to the out-of-plane symmetry being broken, the BP/Ga₂SSe vdWHs are divided into two different stacking patterns, which are BP/SGa₂Se and BP/SeGa₂S. Our results demonstrate that these stacking patterns are structurally and mechanically stable. The combination of single-layer BP and Janus Ga₂SSe gives rise to an enhancement in the Young’s modulus compared to the constituent monolayers. Furthermore, at the ground state, the BP/Ga₂SSe vdWHs possess a type-I (straddling) band alignment, which is desired for next-generation optoelectronic applications. The interlayer separation and electric field are effectively used to tune the electronic features of the BP/Ga₂SSe vdWH from the type-I to type-II band alignment, and from semiconductor to metal. Our findings show that the BP/Ga₂SSe vdWH would be appropriate for next-generation multifunctional optoelectronic and photovoltaic devices.

In this work, we systematically examine the electronic features and contact types of van der Waals heterostructures (vdWHs) combining single-layer boron phosphide (BP) and Janus Ga₂SSe using first-principles calculations.     

The interlayer coupling modulation of a g-C3N4/WTe2 heterostructure for solar cell applications

Constructing van der Waals (vdW) heterostructures has been proved to be an excellent strategy to design or modulate the physical and chemical properties of 2D materials. Here, we investigated the electronic structures and solar cell performances of the g-C₃N₄/WTe₂ heterostructure via first-principles calculations. It is highlighted that the g-C₃N₄/WTe₂ heterostructure presents a type-II band edge alignment with a band gap of 1.24 eV and a corresponding visible light absorption coefficient of ∼10⁶ cm⁻¹ scale. Interestingly, the band gap of the g-C₃N₄/WTe₂ heterostructure could increase to 1.44 eV by enlarging the vdW gap to harvest more visible light energy. It is worth noting that the decreased band alignment difference resulting from tuning the vdW gap, leads to a promotion of the power conversion efficiency up to 17.68%. This work may provide theoretical insights into g-C₃N₄/WTe₂ heterostructure-based next-generation solar cells, as well as a guide for tuning properties of vdW heterostructures.

g-C₃N₄/WTe₂ heterostructure with tunable vdW gap shows a favorable solar energy conversion performance.     

Electronic and optical properties of two-dimensional heterostructures based on Janus XSSe (X = Mo,W) and Mg(OH)2: a first principles investigation

Two-dimensional (2D) materials have attracted numerous investigations after the discovery of graphene. 2D van der Waals (vdW) heterostructures are a new generation of layered materials, which can provide more desirable applications. In this study, the first principles calculation was implemented to study the heterostructures based on Janus TMDs (MoSSe and WSSe) and Mg(OH)₂ monolayers, which were constructed by vdW interactions. Both MoSSe/Mg(OH)₂ and WSSe/Mg(OH)₂ vdW heterostructures have thermal and dynamic stability. Besides, XSSe/Mg(OH)₂ (X = Mo, W) possesses a direct bandgap with a type-I band alignment, which provides promising applications for light-emitting devices. The charge density difference was investigated, and 0.003 (or 0.0042) |e| were transferred from MoSSe (or WSSe) layer to Mg(OH)₂ layer, and the potential drops were calculated to be 11.59 and 11.44 eV across the interface of the MoSSe/Mg(OH)₂ and WSSe/Mg(OH)₂ vdW heterostructures, respectively. Furthermore, the MoSSe/Mg(OH)₂ and WSSe/Mg(OH)₂ vdW heterostructures have excellent optical absorption wave. Our studies exhibit an effective method to construct new heterostructures based on Janus TMDs and develop their applications for future light emitting devices.

Two-dimensional (2D) materials have attracted numerous investigations after the discovery of graphene.     

Intriguing electronic structure and photocatalytic performance of blueP–SMSe and blueP–SeMS (M = Mo,W) van der Waals heterostructures

Van der Waals (vdW) combination of two dimensional (2D) materials in the form of a heterostructure is a widely accepted tool for tailoring properties and designing novel nanoelectronic and energy harvesting applications. The stacking geometry and electronic and photocatalytic properties of vdW heterostructures based on blueP and Janus SMSe and SeMS (M = Mo, W) monolayers are investigated by using first principles calculations. Two alternate stacking configurations of both heterostructures with an alternative order of chalcogen atoms in SMSe and SeMS (M = Mo, W) are constructed and found to be energetically and thermally stable. The feasible stackings of both heterostructures exhibit type-II band alignment (except blueP–SeMoS), hence are promising for light detection devices. In particular, the suitable positions of the valence and conduction band edges of all the heterostructures (except blueP–SMoSe) are appropriate for standard redox potentials and are capable of splitting water into O₂/H₂O and H⁺/H₂. The findings pave the way for potential applications of these heterobilayer systems in future nanoelectronics, optoelectronics and photocatalytic water dissociation.

The stacking geometry and electronic and photocatalytic properties of vdW heterostructures based on blueP and Janus SMSe and SeMS (M = Mo, W) monolayers are investigated using first principles calculations.     

Electronic and photocatalytic properties of two-dimensional boron phosphide/SiC van der Waals heterostructure with direct type-II band alignment: a first principles study

Designing van der Waals (vdW) heterostructures of two-dimensional materials is an efficient way to realize amazing properties as well as opening opportunities for applications in solar energy conversion and nanoelectronic and optoelectronic devices. In this work, we investigate the electronic, optical, and photocatalytic properties of a boron phosphide–SiC (BP–SiC) vdW heterostructure using first-principles calculations. The relaxed configuration is obtained from the binding energies, inter-layer distance, and thermal stability. We show that the BP–SiC vdW heterostructure has a direct band gap with type-II band alignment, which separates the free electrons and holes at the interface. Furthermore, the calculated absorption spectra demonstrate that the optical properties of the BP–SiC heterostructure are enhanced compared with those of the constituent monolayers. The intensity of optical absorption can reach up to about 10⁵ cm⁻¹. The band edges of the BP–SiC heterostructure are located at energetically favourable positions, indicating that the BP–SiC heterostructure is able to split water under working conditions of pH = 0–3. Our theoretical results provide not only a fascinating insight into the essential properties of the BP–SiC vdW heterostructure, but also helpful information for the experimental design of new vdW heterostructures.

We investigate the structural, electronic, optical and photocatalytic properties of boron phosphide and SiC monolayers and their corresponding van der Waals heterostructure by density functional theory.     

Hydrogen bonding sewing interface

The strong force that originates from breaking covalent bonds can be easily quantified through various testing platforms, while weak interfacial sliding resistance (ISR), originating from hydrogen bonding or van der Waals (vdW) forces, is very challenging to measure. Facilitated by an in-house nanomechanical testing system, we are able to precisely quantify and clearly distinguish the interfacial interactions between individual carbon fibers and several substrates governed by either hydrogen bonding or vdW forces. The specific ISR of the interface dominated by vdW forces is 3.55 ± 0.50 μN mm⁻¹ and it surprisingly increases to 157.86 ± 44.18 μN mm⁻¹ if the interface is bridged by hydrogen bonding. The ad hoc studies demonstrate that hydrogen bonding rather than vdW forces has great potential in sewing the interface if both surfaces are supportive of the formation of hydrogen bonds. The findings will enlighten the engineering of interfacial interactions and further mediate the entire mechanical performance of structures.

Hydrogen bonding and van der Waals (vdW) forces have been precisely measured and distinguished by an in-house nanomechanical testing system.     

Boosting the photocatalytic H2 evolution activity of type-II g-GaN/Sc2CO2 van der Waals heterostructure using applied biaxial strain and external electric field

Two-dimensional (2D) van der Waals (vdW) heterostructures are a new class of materials with highly tunable bandgap transition type, bandgap energy and band alignment. Herein, we have designed a novel 2D g-GaN/Sc₂CO₂ heterostructure as a potential solar-driven photocatalyst for the water splitting process and investigate its catalytic stability, interfacial interactions, and optical and electronic properties, as well as the effects of applying an electric field and biaxial strain using first-principles calculation. The calculated lattice mismatch and binding energy showed that g-GaN and Sc₂CO₂ are in contact and may form a stable vdW heterostructure. Ab initio molecular dynamics and phonon dispersion simulations show thermal and dynamic stability. g-GaN/Sc₂CO₂ has an indirect bandgap energy with appropriate type-II band alignment relative to the water redox potentials. Meanwhile, the interfacial charge transfer from g-GaN to Sc₂CO₂ can effectively separate electron–hole pairs. Moreover, a potential drop of 3.78 eV is observed across the interface, inducing a built-in electric field pointing from g-GaN to Sc₂CO₂. The heterostructure shows improved visible-light optical absorption compared to the isolated g-GaN and Sc₂CO₂ monolayers. Our study demonstrates that tunable electronic and structural properties can be realised in the g-GaN/Sc₂CO₂ heterostructure by varying the electric field and biaxial strain. In particular, the compressive strain and negative electric field are more effective for promoting hydrogen production performance. Since it is challenging to tune the electric field and biaxial strain experimentally, our research provides strategies to boost the performance of MXene-based heterojunction photocatalysts in solar harvesting and optoelectronic devices.

Type-II g-GaN/Sc₂CO₂ van der Waals heterostructure with electronic properties has potential for nanoelectronics, optoelectronics and photovoltaic device applications.     

Stacking effects in van der Waals heterostructures of blueP and Janus XYO (X = Ti,Zr, Hf: Y = S,Se) monolayers

Using first-principles calculations, the geometry, electronic structure, optical and photocatalytic performance of blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and their corresponding van der Waal heterostructures in three possible stacking patterns, are investigated. BlueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers are indirect bandgap semiconductors. A tensile strain of 8(10)% leads to TiSeO(ZrSeO) monolayers transitioning to a direct bandgap of 1.30(1.61) eV. The calculated binding energy and AIMD simulation show that unstrained(strained) blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and their heterostructures are thermodynamically stable. Similar to the corresponding monolayers, blueP-XYO (X = Ti, Zr, Hf: Y = S, Se) vdW heterostructures in three possible stacking patterns are indirect bandgap semiconductors with staggered band alignment, except blueP-TiSeO vdW heterostructure, which signifies straddling band alignment. Absorption spectra show that optical transitions are dominated by excitons for blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and the corresponding vdW heterostructures. Both E_VB and E_CB in TiSO, ZrSO, ZrSeO and HfSO monolayers achieve energetically favorable positions, and therefore, are suitable for water splitting at pH = 0, while TiSeO and HfSeO monolayers showed good response for reduction and fail to oxidise water. All studied vdW heterostructures also show good response to any produced O₂, while specific stacking reduces H⁺ to H₂.

Using first-principles calculations, the geometry, electronic structure, optical and photocatalytic performance of blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and their corresponding van der Waal heterostructures in three possible stacking patterns, are investigated.     

Two-dimensional graphene–HfS2 van der Waals heterostructure as electrode material for alkali-ion batteries

Poor electrical conductivity and large volume expansion during repeated charge and discharge is what has characterized many battery electrode materials in current use. This has led to 2D materials, specifically multi-layered 2D systems, being considered as alternatives. Among these 2D multi-layered systems are the graphene-based van der Waals heterostructures with transition metal di-chalcogenides (TMDCs) as one of the layers. Thus in this study, the graphene–hafnium disulphide (Gr–HfS₂) system, has been investigated as a prototype Gr–TMDC system for application as a battery electrode. Density functional theory calculations indicate that Gr–HfS₂ van der Waals heterostructure formation is energetically favoured. In order to probe its battery electrode application capability, Li, Na and K intercalants were introduced between the layers of the heterostructure. Li and K were found to be good intercalants as they had low diffusion barriers as well as a positive open circuit voltage. A comparison of bilayer graphene and bilayer HfS₂ indicates that Gr–HfS₂ is a favourable battery electrode system.

A high rate capacity, moderate volume expansion and energetically stable alkali ion graphene–HfS₂ electrode material.