Exotic Physics and Chemistry of Two-Dimensional Phosphorus

Jun 9, 2017 - Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur-700032, West Bengal, India. J. Phys. Chem. Lett...
16 downloads 14 Views 4MB Size
Download PDF
Perspective pubs.acs.org/JPCL

Exotic Physics and Chemistry of Two-Dimensional Phosphorus: Phosphorene Chandra Chowdhury and Ayan Datta* Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur-700032, West Bengal, India ABSTRACT: Phosphorene, the monolayer form of black phosphorus, is the most recent addition to graphene-like van der Waals two-dimensional (2D) systems. Due to its several interesting properties, namely its tunable direct band gap, high carrier mobility, and unique in-plane anisotropy, it has emerged as a promising candidate for electronic and optoelectronic devices. Phosphorene (Pn) reveals a much richer phase diagram than graphene, and it comprises the two forms namely the stapler-clip like (black Pn, α form) and chairlike (blue Pn, β form) structures. Regardless of its favorable properties, black Pn suffers from instability in oxygen and water, which limits its successful applications in electronic devices. In this Perspective, the cause of structural diversity of Pn, which leads to different properties of both black and blue Pn, is discussed. We provide possible solutions for protecting phosphorene from chemical degradation and its applications in the field of energy storage namely for Li and Na ion batteries.

O

Phosphorus is unique among other pnictogens due to its superconducting behavior at high pressure arising out of its richer phase diagram.12 There are several allotropic forms for phosphorus, namely, white (comprises with monomeric P4 units), red (with extended chain-like amorphous structure), violet or Hittorf’s phosphorus (extended chain-like crystalline structure), A7 phase (layered structure similar to that of silicene) and black phosphorus (hexagonal graphite like structure in which layers are interconnected by van der Waals interactions), and each exhibits extremely different properties.13 Figure 1 shows the various allotropic forms of phosphorus.

wing to their diverse physical, chemical, and optical properties and high surface to volume ratio, twodimensional (2D) materials have emerged as one of the most promising materials for different kind of applications in the materials science community. Among them, graphene, the elemental form of carbon allotrope and the most well-known 2D material lacks a finite band gap, which limits its successful application in the field of electronic and optoelectronic devices.1 Among the post-graphene 2D materials, hexagonal boron nitride (h-BN) has created an attraction, but due to its large band gap (5.9 eV), it becomes an insulator, which prohibits its applications in electronic devices.2 The 2D congeners of graphene, namely, silicene and germanene share similar hexagonal lattice with a buckled structure that arises mainly due to pseudo-Jahn−Teller effects.3−5 However, both of them are not synthesized as a freestanding monolayer, and they require metal surfaces as support. This results in an interaction with the atomic monolayer to the metal surface, which forms covalent bonds, localizing the π-electrons and consequently reducing the electron−hole conductivity.6 Both of them have zero band gaps like graphene. Besides graphene and graphene congeners, there are other 2D materials, like transition metal dichalcogenides (like MoS2, WS2, VS2), functionalized silicane and germanane, single-layer group IV monochalcogenides, and various transition metal carbides, that have been applied successfully in different fields of nanotechnology.7−10 The main drawback of such heteroelemental materials like transition metal dichalcogenides is that there arises deep defect states formed mainly due to chemical disorder of the homoelemental bonds, which are not present in the perfect lattice and can cause degradation of this type of materials.11 This type of bond formation may be avoided in monoelemental materials. Phosphorus, the most abundant pnictogen in Earth’s crust, is located in the third period and group-V of the periodic table. © 2017 American Chemical Society

Not only is black Pn chemically inert, but it also has a typical layered van der Waals-type structure. Among these morphologies, white and red phosphorus are known to be easily ignitable and, hence, air unstable. Black phosphorus is the most thermodynamically stable form out of all phases. In the course of investigation of the effect of high pressure on white phosphorus, Bridgman discovered a new phase of phosphorus (black Pn), namely, black phosphorus from around 100 years ago.14 Not only is black Pn chemically inert, but it also has a typical layered van der Waals-type structure.Interest in black phosphorus was renewed when phosphorene, which is a one-atom-thick layer of black phosphorus, was synthesized as the second real elemental 2D material stable in the free-standing form.15 Black phosphorus Received: May 23, 2017 Accepted: June 9, 2017 Published: June 9, 2017 2909

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

Figure 1. Allotropic forms of phosphorus.

Scheme 1. Exfoliation of Pn Monolayers from Bulk Phosphorus by Different Physical and Chemical Techniques

Figure 2. Structure of (a) an α-P (black), (b) β-P (blue), (c) γ-P, and (d) δ-P monolayer in both top and side views. Top and bottom atom layers are characterized by color and shading. Shaded region represents the Wigner-Seitz cell. Reprinted with permission from ref 21. Copyright 2014 American Physical Society.

generated technological interests when a field effect transistor (FET) with a carrier mobility of 1000 cm2 V−1 s−1 was prepared by Zhang and co-workers in 2014 for a 10 nm-thick multilayer of black Pn.15,16 Few-layer Pn was exfoliated by Castellanos-Gomez et al. through mechanical exfoliation where an intermediate viscoelastic surface was used to increase yield and reduce the possibility of contamination.17 O’Brien and co-workers exfoliated few-layer Pn by using a chemical route, which used a solution of N-methyl2-pyrrolidone.18 This is an emerging field, as materials scientists are working to exfoliate ultrapure Pn layers by different

techniques (Scheme 1), and the literature is expanding day by day.19,20 The main advantage of black Pn is its tunable direct band gap, which varies from 0.3 to 2.0 eV from bulk to monolayer, and, hence, it acts as a bridge between graphene (zero band gap) and hexagonal boron nitride (insulator).16 Besides black Pn, other forms of monolayer Pn have been reported.21−24 Among them, the main three are β, γ, and δ forms. Figure 2 depicts the structure of the four forms from both top and side views. The cohesive energies of all four phases are within 0.1 eV and have been predicted to be stable confirmed by ab initio 2910

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

molecular dynamics simulations.21 α and δ forms exhibit direct band gap semiconductors with gaps of 0.90 and 0.45 eV, respectively, whereas β and γ forms are indirect band gap semiconductors with gaps of 1.98 and 0.50 eV, respectively. Bulk blue Pn is a layered material with a ...ABAB... type of packing and the interlayer distance = 3.48 Å. Since, δ and γ forms of Pn arise from the layered forms of black and blue Pn, we focus our discussion mainly on these two. In this Perspective we discuss how structural diversity leads to the difference in their physical properties and suggest possibilities to improve their chemical and electronic properties for energy applications.

One very distinguishing feature of Pn is its puckered structure, which ultimately controls its properties discussed above. We now discuss how planar Pn gets distorted along e1g and b2g modes, leading to C2h and D3d puckered form of α and β phases, respectively.38 Hexagonal P66− ring is the building unit of Pn. Since P66− ring contains six formed negative charges, it is difficult to converge its geometry, and, hence, the hydrogen terminated analog of this ring, namely, P6H6, is considered. The model unit P6H6 shows an excellent structural resemblance with both black and blue Pn. For example, chair structure of P6H6 in C2h symmetry has two bond distances, d(P−P) = 2.23 and 2.25 Å, which converge well with that of black Pn, which shows two bond distances of d(P−P) = 2.22 and 2.25 Å, respectively. Similarly, for the other stable form of P6H6 in D3d symmetry, a bond length of d(P−P) = 2.27 Å, compares well with bond length of blue Pn d(P−P) = 2.26 Å. All the other structural features of the C2h and D3d forms of P6H6 and that of black and blue Pn are shown in Table 1. Figure 3 shows the molecular

Due to its unique puckered structures, Pn has many fascinating properties that lead to applications not only in device fabrication but also as a catalyst.

Table 1. Comparison of Bond Length (Å), Bond Angle (deg), and Dihedral Angle (deg) of C2h and D3d Symmetry of P6H6 with That of Black and Blue Pna

Properties of Phosphorene. Due to its unique puckered structures, Pn has many fascinating properties that lead to applications not only in device fabrication but also as a catalyst. On applying strain normal to the plane of Pn, it changes from semiconductor to metal, and the change in structural and electronic properties in Pn has been of tremendous interest for fundamental physics studies.25 Application of in-plane strain and out-of-plane electric field on monolayer and few-layer Pn modulated the band gap to convert it into an effective material for solar cell and optoelectronic devices.26 Pn shows unique thermoelectric properties in which the armchair Pn nanoribbons (semiconducting in nature) show large Seebeck coefficients.27 Wei and co-workers showed that Pn can sustain strain up to 27−30% in both directions which is indicative of its superior mechanical flexibility relative to that of other 2D materials like graphene.28 Due to its anisotropic and exceptionally high electron and hole mobility, it is a promising candidate for transistors. For example, a black Pn/monolayer MoS2 heterojunction is fabricated as a p−n diode material, and Pn/TMDs heterojunctions have been predicted to be efficient exitonic solar cell materials.29,30 Recently Sun et al. showed that strain engineering on Pn can act as a good photocatalyst.31 Due to its semiconducting nature, it is also predicted to be good energy storage material, and recent studies have predicted Pn to be excellent anode materials for both Li and Na ion batteries with high specific capacities. 32,33 Using first principle calculations, Liu et al. showed that application of an electric field in the stacking direction leads to normal insulator → topological insulator transition in black Pn.34 Doping is a chemical means to amplify its electronic properties, as the surface states can be effectively manipulated. Using first-principles calculations, it was shown that by adsorption of different metal atoms, namely, alkaline (Na, K, Li), transition (Sc, Ti, V, Cr, Mn, Fe, Co, Ni) and noble metals (Cu, Ag, Au, Pd, Pt), the surface properties of Pn changes, and there is transition from semiconductor → metal and nonmagnetic → magnetic state, which can have applications in dilute magnetic semiconductors.35 Besides adatom doping, doping with charge transfer molecules like tetracyanoquinodimethane (TCNQ), tetrathiafulvalene (TTF), and tetracyanoethylene (TCNE) mid gap states can be created, which decreases the band gap.36,37

dP−P (Å) P6H6, C2h black Pn P6H6, D3d blue Pn

2.23 2.22

2.25 2.25 2.27 2.26

θPPP (deg) 98.7 96.4

100.9 101.2 95.5 93.2

φPPPP (deg) 78.7 80.9

76.9 77.1 83.9 86.7

a

Reprinted with permission from ref 38. Copyright 2016 American Chemical Society.

Figure 3. Correlation between (a) molecular form of P6H6 with C2h symmetry to black Pn and (b) P6H6 with D3d symmetry to blue Pn. The shaded region corresponds to the molecular form of P66− ring and relates its connection to the extended form. Reprinted with permission from ref 38. Copyright 2016 American Chemical Society.

form of P6H6 structures in both C2h and D3d and how they transform into the extended layers preparing their basic unit intact. Pseudo-Jahn−Teller Instability of Planar Phosphorene. The planar form of P6H6 has a hexagonal geometry with D6h point group symmetry. This form is a saddle point producing 11 unstable normal modes, namely, 4E2u + 2B2g + 2E1g + 1B1u + 2E2g. Among these modes, relaxation only along e1g and b2g modes produces the vibrationally stable forms with C2h and D3d symmetry, respectively, and the others formed structures that 2911

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

Figure 4. Animation of distortion in P6H6 along (a) e1g and (b) b2g modes. The APES for (c) e1g and (d) b2g for ground state and several excited states. Numerical fitting of the ground state APES to the lowest root of the 4 × 4 secular determinant for PJT along (e) e1g mode and (f) b2g mode. Reprinted with permission from ref 38. Copyright 2016 American Chemical Society.

excited electronic states is that the states should lie within a reasonable energy range, which is satisfied for both E1g and B2g electronic states in which the relevant excited states are at 2.99, 3.06, and 4.01 eV with respect to the ground state. There are several examples where, due to the highly separated electronic states, symmetry lowering does not occur by means of PJT distortion like that for graphene, highly electronegative element (F/O) substituted dithine rings, or Li(I)/Ca(II)-doped silicene.40−42 From Figure 4, it is clear that the ground state APES gets stabilized, which creates a typical double-well potential, and the energy barrier for this is 1.4 kcal/mol at q(e1g)/q(b2g) = 0. Two PJT problems were set up for the distortion of P6H6 molecule along e1g and b2g modes by coupling of three excited states of E1g and B2g symmetry, and the PJT problem resembles (1Ag + 1E1g + 2E1g + 3E1g) × e1g and (1Ag + 1B2g + 2B2g + 3B2g) × b2g for e1g and b2g, respectively. This problem results in a 4 × 4 secular determinant. Solution of this determinant gives equations that were fitted with the ground states APES of e1g and b2g mode and shown in Figure 4(e) and 4(f), respectively. From the result of this fitting of the APES, the relevant vibronic couplings, primary force constants including the second-order perturbation correction and effective ground state force constants, are obtained. The general condition for

are not stable. In Figure 4(a) and 4(b), the animation of the normal modes frequencies along e1g and b2g modes are shown. The energy difference between these two structures is very small, and it was found that the C2h form is more stable than the D3d form by −4.3 kcal/mol. This is consistent with the previous studies of PPh6, which show that it is more stable in its chair form than that of its other forms.39 From Figure 3, it is seen that both the C2h and D3d forms exist in chair-like structures, and it may be possible to extend these two structures into black and blue Pn with a small energy penalty. This is in agreement with the small energy difference of 0.01 eV/atom between the two phases.21 For understanding the stability of black and blue Pn in C2h and D3d forms in P6H6 geometry, distortion of planar P6H6 along the vibrational symmetry modes e1g and b2g was undertaken to generate adiabatic potential energy surfaces (APES). In Figure 4(c) and 4(d), the APES for both e1g and b2g were plotted for the ground state and a few relevant excited states, respectively. From the calculation, it is clear that for both e1g and b2g modes, 20−25 excited states lie within the energy range 4 eV, which implies that several excited states might be approachable by low energy excitation for both cases. The favorable condition for effective nonadiabatic coupling between ground states and several 2912

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

Besides this, it is revealed from both experimental and theoretical calculations that, though pristine Pn weakly interacts with water, in the case where Pn is oxidized, this oxidized surface reacts rapidly with water molecule (exothermic reaction), which appears to be the main reason for chemical degradation of Pn-based electronic devices.46 Island and co-workers showed that in a 5-day period, black Pn flakes with a maximum of 30 nm thickness aer totally covered with water, resulting in a large convex meniscus.47 To prevent this degradation, Pn should be encapsulated. Several recent studies have shown that the stability of Pn flakes can be improved using atomic layer deposition (ALD) of a dielectric layer like alumina, solvent exfoliation with anhydrous organic solvent like N-methylpyrrolidone (NMP), or N-cyclohexyl-2-pyrrolidone, etc.18 In Figure 5, it is shown schematically how oxygen plasma etching can react with the top Pn layer producing PxOy, which effectively protects Pn from degradation, and this is further improved by passivation with Al2O3 by ALD.48 Another promising way to protect reactive Pn is capping with naturally stable 2D materials like graphene or BN. The Pn/graphene or Pn/h-BN heterostructure preserves the main characteristics of Pn, which are the main reason for device applications.49 Pn/h-BN Heterostructure and Its Potential as LIBs. In terms of energy density, chemical energy is the most appropriate source. For next-generation energy storage devices, Li ion battery (LIB) and Na ion battery (SIB) have gained prime interest among the other available energy storage devices. LIBs are attractive as anode materials in batteries due to their high energy density, good cycle life and enhanced rate capabilities.50 Pn monolayers and bilayers have also been explored as anodes for LIBs and SIBs with high theoretical capacity.25,32 However, as discussed above, due to its high reactivity toward atmospheric oxidation, the electronic properties are altered significantly and hence impede its application in such advanced electronic devices. Structural and chemical degradation of Pn might be avoided by capping it with graphene or hexagonal boron nitride (h-BN), thus Pn capped with graphene or h-BN can act as a good electrode material. Pn/graphene heterostructures have been demonstrated to be good electrode materials for both LIBs and SIBs in both experimental and theoretical studies.51,52 Recently, Pn capped with h-BN has been

For understanding the stability of black and blue Pn in C2h and D3d forms in P6H6 geometry, distortion of planar P6H6 along the vibrational symmetry modes e1g and b2g was undertaken to generate adiabatic potential energy surfaces. satisfying the PJT instability is ∑i

2F02i Δ0i

> k 0 − p0 , where F0i is

the coupling constant, Δ0i is the energy difference between the ground state and the excited state, and (k0 − p0) is the ground state force constant, and for both e1g and b2g the instability condition is satisfied.43 So, it is clear that the reason for the puckered structure of planar P6H6 ring is the spontaneous symmetry breaking arising due to PJT. From this discussion it can be concluded that planar Pn can not be stable, and it may spontaneously break down to form either buckled black or puckered blue Pn to avoid PJT instability in its planar form. Planar P6 molecule in D6h symmetry is not stable, and it spontaneously undergoes symmetry lowering (D2) by the (HOMO−1) and LUMO vibronic mixing along the puckering mode (e2u).44 Instability arising out of pseudo-JT distortions account for the black and blue phases of Pn, which, though energetically almost degenerate, possess very different chemical and physical properties. Blue Pn is significantly less undulated than black Pn and should therefore possess more exposed area to interact with planar molecular surfaces. Hence, the extent of charge transfer (CT) to and from black and blue Pn would be different, which must affect their electronic properties. Major Problem and Possible Remedies. Although Pn has a large number of applications due to its outstanding properties, a significant bottleneck comes due to its instability in air. Previous studies show that Pn is unstable at ambient conditions, and it gets oxidized to form phosphorene oxide and other oxide fragments of low molecular weight.45−48

Figure 5. Schematic representation of fabrication of air stable mono- to few-layer Pn. Reproduced with permission from ref 48. (http:// creativecommons.org/licenses/by/4.0/). 2913

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

usefulness as an electronic device and energy storage applications, it can also be used in other emerging areas as well in material science. We list few of them here: (1) Over the past decade, two-dimensional materials have been used in a variety of reactions, including the oxygen reduction reaction, water splitting, and CO2 activation, and have been shown to provide excellent catalytic support. Due to its layered van der Waals type unique structure, Pn can be an attractive two-dimensional support for heterogeneous catalysts. Besides the pristine form, doped Pn with electronegative groups such as, for example, frustrated Lewis pair-based Pn, can also be an attractive 2D catalyst.54 The possibility of exploiting doped Pn surfaces in heterogeneous catalysis, namely, single atom catalyst (SAC), is anticipated in the near future. (2) Phosphorus is an essential element in the cell. Hence, one might design biomedical applications for Pn, and biomolecular interactions, cell imaging, drug delivery, and toxicity for Pn-based materials need to be explored. Besides this, Pn can also be used as a biosensor, namely, DNA detection based on π−π stacking and hydrophobic interactions. (3) Molecular self-assembly on 2D surfaces is emerging as an interesting area of research. 2D black Pn can be an excellent surface for molecular self-assembly and, hence, utilized for the epitaxial growth of organic thin films for various optoelectronic devices, namely, organic light emitting diodes (OLEDs), organic photovoltaic (OPVs),

Structural and chemical degradation of Pn might be avoided by capping it with graphene or hexagonal boron nitride (h-BN), thus Pn capped with graphene or h-BN can act as a good electrode material. demonstrated to act as a good anode material for both Li and Na ion batteries.53 Such Pn/h-BN heterostructure exhibits very small diffusion barriers of 0.09 and 0.06 eV for Li and Na, respectively (Figure 6), and this advocates an excellent diffusion mobility and high charge−discharge rate for Li and Na atoms in the LIB and SIB. It was further shown that capping Pn by h-BN not only prevents chemical degradation of Pn but also improves its performance without perturbing its intrinsic in-plane high specific capacity.

■

SUMMARY AND OUTLOOK Due to its suitable physical and chemical properties, Pn has tremendous applications in the field of electronic and optoelectronic devices which has become an attractive area. Motivated by the desire to develop next-generation electronic and optoelectronic devices, a plethora of research has been carried out after initial experiments showed that few-layer and monolayer BP flakes can be exfoliated like graphene. Besides its

Figure 6. Schematic representation of the diffusion path of alkali (a) along the intercalated region between the h-BN and Pn layers and (b) above the surface of the Pn layer, (c) the diffusion barrier for Li along the armchair and zigzag pathways in the intercalated region, (d) the diffusion barrier for Na along the armchair and zigzag pathways in the intercalated region, (e) the diffusion barrier for Li along the armchair and zigzag pathway over the Pn surface, and (f) the diffusion barrier for Na along the armchair and zigzag pathways over the Pn surface. Reprinted with permission from ref 53. Copyright 2016 American Chemical Society. 2914

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

■

Perspective

and organic field effect transistors (OFETs).55 The dispersion interactions between the hexagonal P6 units and aromatic/aliphatic molecules can lead to interesting nanopatterns.

(12) Kawamura, H.; Shirotani, I.; Tachikawa, K. Anomalous Superconductivity in Black Phosphorus under High Pressures. Solid State Commun. 1984, 49, 879−881. (13) Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements; Elsevier: Oxford, U.K., 2012. (14) Bridgman, P. Two New Modifications of Phosphorus. J. Am. Chem. Soc. 1914, 36, 1344−1363. (15) Li, L.; Yu, Y.; Ye, G. J.; Ge, Q.; Ou, X.; Wu, H.; Feng, D.; Chen, X. H.; Zhang, Y. Black Phosphorus Field-Effect Transistors. Nat. Nanotechnol. 2014, 9, 372−377. (16) Liu, H.; Neal, A. T.; Zhu, Z.; Luo, Z.; Xu, X.; Tománek, D.; Ye, P. D. Phosphorene: An Unexplored 2D Semiconductor with a High Hole Mobility. ACS Nano 2014, 8, 4033−4041. (17) Castellanos-Gomez, A.; Vicarelli, L.; Prada, E.; Island, J. O.; Narasimha-Acharya, K.; Blanter, S. I.; Groenendijk, D. J.; Buscema, M.; Steele, G. A.; Alvarez, J.; et al. Isolation and Characterization of FewLayer Black Phosphorus. 2D Mater. 2014, 1, 025001. (18) Brent, J. R.; Savjani, N.; Lewis, E. A.; Haigh, S. J.; Lewis, D. J.; O’Brien, P. Production of Few-Layer Phosphorene by Liquid Exfoliation of Black Phosphorus. Chem. Commun. 2014, 50, 13338− 13341. (19) Liu, H.; Du, Y.; Deng, Y.; Ye, P. D. Semiconducting Black Phosphorus: Synthesis, Transport Properties and Electronic Applications. Chem. Soc. Rev. 2015, 44, 2732−2743. (20) Jing, Y.; Zhang, X.; Zhou, Z. Phosphorene: What Can We Know From Computations? WIREs Comput. Mol. Sci. 2016, 6, 5−19. (21) Guan, J.; Zhu, Z.; Tománek, D. Phase Coexistence and MetalInsulator Transition in Few-Layer Phosphorene: A Computational Study. Phys. Rev. Lett. 2014, 113, 046804. (22) Liu, D.; Guan, J.; Jiang, J.; Tomanek, D. Unusually Stable Helical Coil Allotrope of Phosphorus. Nano Lett. 2016, 16, 7865− 7869. (23) Zhang, J.; Zhao, D.; Xiao, D.; Ma, C.; Du, H.; Li, X.; Zhang, L.; Huang, J.; Huang, H.; Jia, C.-L.; et al. Assembly of Ring-Shaped Phosphorus within Carbon Nanotube Nanoreactors. Angew. Chem., Int. Ed. 2017, 56, 1850−1854. (24) Wu, M.; Fu, H.; Zhou, L.; Yao, K.; Zeng, X. C. Nine New Phosphorene Polymorphs with Non-Honeycomb Structures: A Much Extended Family. Nano Lett. 2015, 15, 3557−3562. (25) Rodin, A.; Carvalho, A.; Castro Neto, A. Strain-Induced Gap Modification in Black Phosphorus. Phys. Rev. Lett. 2014, 112, 176801. (26) Li, Y.; Yang, S.; Li, J. Modulation of the Electronic Properties of Ultrathin Black Phosphorus by Strain and Electrical Field. J. Phys. Chem. C 2014, 118, 23970−23976. (27) Zhang, J.; Liu, H.; Cheng, L.; Wei, J.; Liang, J.; Fan, D.; Shi, J.; Tang, X.; Zhang, Q. Phosphorene Nanoribbon As a Promising Candidate For Thermoelectric Applications. Sci. Rep. 2015, 4, 6452. (28) Wei, Q.; Peng, X. Superior Mechanical Flexibility of Phosphorene and Few-Layer Black Phosphorus. Appl. Phys. Lett. 2014, 104, 251915. (29) Deng, Y.; Luo, Z.; Conrad, N. J.; Liu, H.; Gong, Y.; Najmaei, S.; Ajayan, P. M.; Lou, J.; Xu, X.; Ye, P. D. Black Phosphorus−Monolayer MoS2 Van der Waals Heterojunction P−N Diode. ACS Nano 2014, 8, 8292−8299. (30) Ganesan, V. D. S. O.; Linghu, J.; Zhang, C.; Feng, Y. P. Heterostructures of Phosphorene and Transition Metal Dichalcogenides for Excitonic Solar Cells: A First-Principles Study. Appl. Phys. Lett. 2016, 108, 122105. (31) Sa, B.; Li, Y.-L.; Qi, J.; Ahuja, R.; Sun, Z. Strain Engineering for Phosphorene: The Potential Application As a Photocatalyst. J. Phys. Chem. C 2014, 118, 26560−26568. (32) Li, W.; Yang, Y.; Zhang, G.; Zhang, Y.-W. Ultrafast and Directional Diffusion of Lithium in Phosphorene for High-Performance Lithium-Ion Battery. Nano Lett. 2015, 15, 1691−1697. (33) Kulish, V. V.; Malyi, O. I.; Persson, C.; Wu, P. Phosphorene As an Anode Material for Na-Ion Batteries: A First-Principles Study. Phys. Chem. Chem. Phys. 2015, 17, 13921−13928.

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Ayan Datta: 0000-0001-6723-087X Notes

The authors declare no competing financial interest. Biographies Chandra Chowdhury is currently a senior research scholar in the Department of Spectroscopy, IACS, Kolkata. Her research interest is computational materials science focused mainly towards energy storage and environmental issues. Dr. Ayan Datta is currently an Associate Professor in the Department of Spectroscopy, IACS, Kolkata. His research interests span across various aspects of theoretical and computational chemistry. Special emphasis is given to provide qualitative models to understand and predict the structure, reactivity, and physical properties of molecules and materials at various lengths and time scales.

■

ACKNOWLEDGMENTS C.C. thanks CSIR India for SRF. A.D. thanks INSA, DST, and BRNS for partial funding.

■

REFERENCES

(1) Papagno, M.; Rusponi, S.; Sheverdyaeva, P. M.; Vlaic, S.; Etzkorn, M.; Pacilé, D.; Moras, P.; Carbone, C.; Brune, H. Large Band Gap Opening Between Graphene Dirac Cones Induced by Na Adsorption onto an Ir Superlattice. ACS Nano 2012, 6, 199−204. (2) Watanabe, K.; Taniguchi, T.; Kanda, H. Direct-Bandgap Properties and Evidence for Ultraviolet Lasing of Hexagonal Boron Nitride Single Crystal. Nat. Mater. 2004, 3, 404−409. (3) Jose, D.; Datta, A. Structures and Chemical Properties of Silicene: Unlike Graphene. Acc. Chem. Res. 2014, 47, 593−602. (4) Jose, D.; Datta, A. Understanding of the Buckling Distortions in Silicene. J. Phys. Chem. C 2012, 116, 24639−24648. (5) Nijamudheen, A.; Bhattacharjee, R.; Choudhury, S.; Datta, A. Electronic and Chemical Properties of Germanene: The Crucial Role of Buckling. J. Phys. Chem. C 2015, 119, 3802−3809. (6) Hogan, C.; Colonna, S.; Flammini, R.; Cricenti, A.; Ronci, F. Structure and Stability of Si/Ag (110) Nanoribbons. Phys. Rev. B: Condens. Matter Mater. Phys. 2015, 92, 115439. (7) Rao, C.; Ramakrishna Matte, H.; Maitra, U. Graphene Analogues of Inorganic Layered Materials. Angew. Chem., Int. Ed. 2013, 52, 13162−13185. (8) Rupp, C. J.; Chakraborty, S.; Anversa, J.; Baierle, R. r. J.; Ahuja, R. Rationalizing the Hydrogen and Oxygen Evolution Reaction Activity of Two-Dimensional Hydrogenated Silicene and Germanene. ACS Appl. Mater. Interfaces 2016, 8, 1536−1544. (9) Karmakar, S.; Chowdhury, C.; Datta, A. Two-Dimensional Group IV Monochalcogenides: Anode Materials for Li-Ion Batteries. J. Phys. Chem. C 2016, 120, 14522−14530. (10) Naguib, M.; Mashtalir, O.; Carle, J.; Presser, V.; Lu, J.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W. Two-Dimensional Transition Metal Carbides. ACS Nano 2012, 6, 1322−1331. (11) Liu, Y.; Xu, F.; Zhang, Z.; Penev, E. S.; Yakobson, B. I. TwoDimensional Mono-elemental Semiconductor with Electronically Inactive Defects: The Case of Phosphorus. Nano Lett. 2014, 14, 6782−6786. 2915

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916

The Journal of Physical Chemistry Letters

Perspective

Hydrogenation of Small Unsaturated Molecules. ACS Catal. 2017, 7, 766−771. (55) Mukhopadhyay, T. K.; Datta, A. Ordering and Dynamics for the Formation of Two-Dimensional Molecular Crystals on Black Phosphorene. J. Phys. Chem. C 2017, 121, 10210−10223.

(34) Liu, Q.; Zhang, X.; Abdalla, L.; Fazzio, A.; Zunger, A. Switching a Normal Insulator into a Topological Insulator via Electric Field with Application to Phosphorene. Nano Lett. 2015, 15, 1222−1228. (35) Hu, T.; Hong, J. First-Principles Study of Metal Adatom Adsorption on Black Phosphorene. J. Phys. Chem. C 2015, 119, 8199− 8207. (36) Zhang, R.; Li, B.; Yang, J. A First-Principles Study on Electron Donor and Acceptor Molecules Adsorbed on Phosphorene. J. Phys. Chem. C 2015, 119, 2871−2878. (37) Jing, Y.; Tang, Q.; He, P.; Zhou, Z.; Shen, P. Small Molecules Make Big Differences: Molecular Doping Effects on Electronic and Optical Properties of Phosphorene. Nanotechnology 2015, 26, 095201. (38) Chowdhury, C.; Jahiruddin, S.; Datta, A. Pseudo-Jahn−Teller Distortion in Two-Dimensional Phosphorus: Origin of Black and Blue Phases of Phosphorene and Band Gap Modulation by Molecular Charge Transfer. J. Phys. Chem. Lett. 2016, 7, 1288−1297. (39) Yoshifuji, M.; Inamoto, N.; Ito, K.; Nagase, S. Ab Initio Calculation of Diphosphene and Cyclopolyphosphanes. Chem. Lett. 1985, 14, 437−440. (40) Mandal, T. K.; Jose, D.; Nijamudheen, A.; Datta, A. Structures and Electronic Properties of Heavier Congeners of Disk-Like Molecules:(Si, Ge) Sulflower and (Si, Ge) Olympicene. J. Phys. Chem. C 2014, 118, 12115−12120. (41) Pratik, S. M.; Chowdhury, C.; Bhattacharjee, R.; Jahiruddin, S.; Datta, A. Pseudo Jahn−Teller Distortion for a Tricyclic Carbon Sulfide (C6S8) and Its Suppression in S-Oxygenated Dithiine (C4H4(SO2)2). Chem. Phys. 2015, 460, 101−105. (42) Pratik, S. M.; Nijamudheen, A.; Datta, A. Topochemical Transformations of CaX2 (X= C, Si, Ge) to Form Free-Standing TwoDimensional Materials. Chem. - Eur. J. 2015, 21, 18454−18460. (43) Bersuker, I. B. Pseudo-Jahn−Teller Effect- A Two-State Paradigm in Formation, Deformation, and Transformation of Molecular Systems and Solids. Chem. Rev. 2013, 113, 1351−1390. (44) Ivanov, A. S.; Bozhenko, K. V.; Boldyrev, A. I. On the Suppression Mechanism of the Pseudo-Jahn−Teller Effect in Middle E6 (E= P, As, Sb) Rings of Triple-Decker Sandwich Complexes. Inorg. Chem. 2012, 51, 8868−8872. (45) Ziletti, A.; Carvalho, A.; Campbell, D. K.; Coker, D. F.; Castro Neto, A. Oxygen Defects in Phosphorene. Phys. Rev. Lett. 2015, 114, 046801. (46) Wang, G.; Slough, W. J.; Pandey, R.; Karna, S. P. Degradation of Phosphorene in Air: Understanding at Atomic Level. 2D Mater. 2016, 3, 025011. (47) Island, J. O.; Steele, G. A.; van der Zant, H. S.; CastellanosGomez, A. Environmental Instability of Few-Layer Black Phosphorus. 2D Mater. 2015, 2, 011002. (48) Pei, J.; Gai, X.; Yang, J.; Wang, X.; Yu, Z.; Choi, D.-Y.; LutherDavies, B.; Lu, Y. Producing Air-Stable Monolayers of Phosphorene and Their Defect Engineering. Nat. Commun. 2016, 7, 10450. (49) Cai, Y.; Zhang, G.; Zhang, Y.-W. Electronic Properties of Phosphorene/Graphene and Phosphorene/Hexagonal Boron Nitride Heterostructures. J. Phys. Chem. C 2015, 119, 13929−13936. (50) Goriparti, S.; Miele, E.; De Angelis, F.; Di Fabrizio, E.; Zaccaria, R. P.; Capiglia, C. Review on Recent Progress of Nanostructured Anode Materials for Li-Ion Batteries. J. Power Sources 2014, 257, 421− 443. (51) Sun, J.; Lee, H.-W.; Pasta, M.; Yuan, H.; Zheng, G.; Sun, Y.; Li, Y.; Cui, Y. A Phosphorene−Graphene Hybrid Material as a HighCapacity Anode for Sodium-Ion Batteries. Nat. Nanotechnol. 2015, 10, 980−985. (52) Guo, G.-C.; Wang, D.; Wei, X.-L.; Zhang, Q.; Liu, H.; Lau, W.M.; Liu, L.-M. First-Principles Study of Phosphorene and Graphene Heterostructure as Anode Materials for Rechargeable Li Batteries. J. Phys. Chem. Lett. 2015, 6, 5002−5008. (53) Chowdhury, C.; Karmakar, S.; Datta, A. Capping Black Phosphorene by h-BN Enhances Performances in Anodes for Li and Na Ion Batteries. ACS Energy Lett. 2016, 1, 253−259. (54) Zhao, J.; Liu, X.; Chen, Z. Frustrated Lewis Pair Catalysts in Two-Dimension: B/Al-Doped Phosphorene as Promising Catalysts for 2916

DOI: 10.1021/acs.jpclett.7b01290 J. Phys. Chem. Lett. 2017, 8, 2909−2916