Structure and Interaction of Ionic Liquid Monolayer on Graphite from

Subscriber access provided by AUSTRALIAN NATIONAL UNIV

C: Surfaces, Interfaces, Porous Materials, and Catalysis

Structure and Interaction of Ionic Liquid Monolayer on Graphite from First Principles Shaoze Zhang, Yunxiang Lu, Changjun Peng, Honglai Liu, and De-en Jiang J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b10664 • Publication Date (Web): 10 Dec 2018 Downloaded from http://pubs.acs.org on December 15, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

Structure and Interaction of Ionic Liquid Monolayer on Graphite from First Principles Shaoze Zhang,†,‡ Yunxiang Lu,‡ Changjun Peng,‡ Honglai Liu,‡ and De-en Jiang*,† †Department ‡Key

of Chemistry, University of California, Riverside, California 92521, United States

Laboratory for Advanced Materials and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China *Corresponding author: [email protected].

ABSTRACT The ionic-liquid/graphite interface is important in understanding the behaviors of the ionic-liquid electrolyte in carbon-based supercapacitors and Li-ion batteries. A row-like cation-anion structure of the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP][TFSA]) ionic liquid (a popular choice for interfacial studies) on the graphite surface has been suggested based on scanning tunneling microscopy images, but it is unclear if this structure is the most stable one. Herein we explore alternative models of the [BMP][TFSA] monolayer on graphite basal plane with first principles density functional theory. We find that the checkerboard type of structure is in fact more stable than the row-like structure. We further use simulated annealing based on classical molecular dynamics simulations to obtain more stable conformations of ions on the surface. Both charge-density-difference and noncovalent-interaction analyses show that the higher stability of the checkerboard structure than the row-like structure is due to the stronger anionsurface interactions in the former. Our work therefore suggests a new model of the [BMP][TFSA] monolayer on the graphite basal plane.

ACS Paragon Plus Environment

1

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 19

INTRODUCTION Ionic liquids (ILs) have attracted growing interest due to their noninflammability, extremely low vapor pressure, great tunability, and large electrochemical window. These characteristics make ionic liquids key candidates for the development of electrochemical applications such as the polymer-electrolyte-membrane fuel cells, high-rate lithium-ion batteries, and supercapacitors.1-7 The interfacial structure, dynamics, and transport of ILs at the electrode interface govern the performances of these devices. Great progress has been made in understanding the IL/electrode interface through both various characterization techniques and computational modeling.8-12 Scanning probe microscopy (SPM), including scanning tunneling microscopy (STM) and atomic force microscopy (AFM), can provide geometrical information through real-time and realspace images of the interface with resolution up to atomic level.13-15 SPM has been widely employed to probe ion adsorption, electrode surface morphology, metal electrodeposition, and molecular self-assembly at the IL/electrode interface.16-27 For example, efforts have been made to understand the interactions of ILs with metal surfaces, such as Au(111), Au(100), Ag(111) and Cu(111).16-21,

23-25, 27

One of the popular choices of ILs for such studies is 1-butyl-1-

methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP][TFSA]). It was found that the [BMP][TFSA] IL induced the reconstruction of Au(111).16 Gnahm et al. synthesized a series of hexaalkylguanidinium-based ionic liquids and used in situ STM to reveal the reconstructions of the ILs on Au(100) and Au(111) facets.19 The interaction between [BMP][TFSA] and Ag(111) was also investigated under ultrahigh-vacuum conditions by STM.20 Dispersion-corrected density functional theory calculation (DFT-D) has often been used to interpret and corroborate the images from STM experiments, in order to resolve the interfacial structure at the atomic level. DFT-D can also provide information regarding the interfacial charge


2

Page 3 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


transfer.

28-35

However, due to their high computational cost, DFT-D calculations have been

limited to small unit cells and a little portion of the configurational space of ILs on the metal surface. In most cases, only one ion pair was placed in the slab model to simulate the ILs adsorbed on the surfaces, including the substrate.20, 22, 26, 29, 32 For example, the DFT-D calculations were used to understand the self-assembled structure of the ILs on highly oriented pyrolytic graphite (HOPG) and a row-like structure (cation-anion-cation-anion) was proposed.26 But more stable structures could exist. In this work, we aim to explore more structural models of ILs self-assembled on graphite using [BMP][TFSA] as an example, in order to gain deeper insight into the nature of IL-graphite interactions as well as the ion-pair interactions and noncovalent interactions. To explore the energy landscape of the IL on the graphite surface, we use periodic DFT calculations with dispersion correction, corroborated by simulated annealing with classical molecular dynamics simulations. To examine the IL-graphite interactions, we employ the analyses based on the electron density difference (EDD) and the electron density gradient. COMPUTATIONAL METHODOLOGY All periodic DFT calculations were performed by means of the Vienna Ab initio Simulation Package (VASP, version 5.3.5)36-39 with the projector-augmented wave (PAW)40 potentials and with the plane-wave bases (cutoff energy of 400 eV). The generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) was used to describe electron exchange-correlation.41 The DFT-D3 method42 was applied to include dispersion; the Becke-Johnson damping43 with the most recent damping function44 was employed to avoid the vanishing forces at short distances. All structures were relaxed until the forces on each atom were below 0.05 eV/Å. To model graphite, the graphene bilayer (A-B stacking) was employed to save the computational


3


Page 4 of 19

cost; the topmost layer was free to relax during the optimization, while the lower layer was kept frozen at the optimized bulk positions. Moreover, a vacuum layer of 20 Å was introduced to along the c axis to minimize the interactions between slab images. The lattice parameters for modeling the isolated molecules, slab, and self-assembly systems are listed in Table S1. The adsorption energy (Eads) was evaluated as Eads = [Esystem – nE(ion pair) – Esurface]/n where Esystem is the energy of the optimized IL/graphite system; E(ion

(1) pair)

is the energy of an

optimized ion pair within a large box with dipole correction applied in all directions; Esurface is the total energy of the bare graphite surface, and n is the number of IL ion-pair in the system. To confirm the stability of the proposed structures based on DFT geometry, simulated annealing with classical molecular dynamic (CMD) simulations was performed with the LAMMPS package45 in the canonical (NVT) ensemble with two-dimensional periodic boundary conditions. Lennard-Jones parameters were from the CVFF force filed;46 the parameters for the bonded terms of the [BMP] cation and [TFSA] anion were from Borodin.47 Partial atomic charges for the cation and anion were obtained by fitting to the electrostatic potential at the B3LYP/6-31G(d) level from the RESP method of the Merz–Kollman scheme, while the partial charges of the carbon atoms in graphite were set at zero. Lennard-Jones (LJ) potential terms were evaluated via the LorentzBerthelot mixing rules with a cutoff of 12 Å. Both the partial charges and the LJ parameters are provided in the Supporting Information (Figure S1, Tables S2 and S3). To calculate the long-range electrostatic interaction in the 2D periodic simulation cell, we used the 3D Particle-ParticleParticle-Mesh (PPPM) method with a slab correction for our simulations. For each simulation, the system was heated up to 500K for 5ns and quenched to 300K in 5ns and then 0K in another 5ns. The annealed structure was then re-optimized with DFT-D3.


4

Page 5 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


RESULTS AND DISCUSSIONS Characteristics of the [BMP][TFSA] IL. [BMP][TFSA] is a popular IL used for formation of the SAMs on surfaces. The electrostatic potential of the cation and the two conformations (cis- vs. trans-) of the anion are shown in Figure 1. The most positive regions for the cation are found between the N atom of the pyrrolidinium ring and the methyl group attached it. For both cis- and trans- isomers of [TFSA]-, the space between the two sulfonyl groups is the most negative region.

Figure 1. The electrostatic potential (ESP) mapped to the van der Waals surface (electron-density isosurface = 0.001 au) of cation and anions; positions of maximum and minimum ESP values also indicated.

Geometries and energies for self-assembled monolayer (SAM) of [BMP][TFSA] on graphite. The most likely structures of SAMs of [BMP][TFSA] on graphite can be divided into two main types: row-like (type I) and checkerboard (type II). For type I model, we followed a previous study that suggested the model based on a joint STM/DFT study.26 We further constructed eight configurations according to the orientations of the cation and the cis- and trans-conformations of


5


Page 6 of 19

the anion and then optimized their structures with DFT-D3. The optimized structures are displayed in Figure 2; the average heights of the ions above the surface are listed in Table S4. We find that the pyrrolidinium ring of the cation prefers to be parallel to the surface, while the anion tends to form strong electrostatic interactions with the cation and tilts away from the graphite surface to some extent.

Figure 2. Type I model of the [BMP][TFSA] IL on graphite basal plane: row-like assembly of cations and anions. For each panel, upper picture is top view and lower picture is side view. Only the top layer of the substrate is displayed for clarity. Coverage: 0.80 ion-pair/nm2. C, gray; H, white; N, blue; S, yellow; O, red; F, cyan. Same color scheme is used in subsequent figures.


6

Page 7 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


For type II model of the checkerboard configuration (Figure 3), we first tested different sizes of the lateral unit cell for accommodating two ion pairs and obtained a coarsely optimized coverage of 1.06/nm2 based on two ion pairs in a unit cell of 1.23 nm by 1.48 nm. From this unit cell, we then constructed eight configurations and optimized their structures. We find that the anion and the substrate are much closer in type II models than in type I models. Figure 4 compares adsorption energy per the ion pair on the graphite surface for the 16 candidate SAM structures in Figures 2 and 3. One can see that the most stable two structures are of type II with cis-TFSA anion. Figure 4 suggests that the checkerboard structure (type II) is more favorable than the row-like structure (type I).

Figure 3. Type II model of the [BMP][TFSA] IL on graphite basal plane: checkerboard-like assembly of cations and anions. For each panel, upper picture is top view and lower picture is side view. Only the top layer of the substrate is displayed for clarity. Coverage: 1.06 ion-pair/nm2.


7


Page 8 of 19

Figure 4. Comparison of adsorption energies per ion pair for the eight type-I (Figure 2) and eight type-II (Figure 3) models of the self-assembled monolayer of the [BMP][TFSA] IL on graphite basal plane. For each type, the structures are further divided into two sub-types with four for cisTFSA and four for trans-TFSA.

To further explore the stability of the most stable DFT structure (type II: BMP-cis-TFSA4), simulated annealing with classical molecular dynamics (CMD) was performed. Starting with the DFT-optimized structure, the system was heated up to 500K for 5ns and quenched to 300K in 5ns and then to 0K in another 5ns. After the simulated annealing with CME, DFT-D3 was employed again to optimize the structure. We used the ordered structure from DFT for the ionic liquid monolayer on graphite as the initial structure (Figure 3) for classical MD (CMD) simulations to heat up the system with a 2D periodic condition. At 500K, the geometries of cations and anions were changed to some extent, but they remain ordered, due to the constraints from the small DFT unit cell. Here again, we emphasize that the purpose of the simulated annealing from the CMD was to further lower the energy by allowing the side-chain groups to adapt to the surface and the ion-ion interactions. We found that the energy of the SAM structure (type II: BMP-cis-TFSA-4)


8

Page 9 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


is further lowered by 0.18 eV per ion pair (Figure 5). One can see that after simulated annealing, the checkerboard pattern is maintained, the pyrrolidinium ring becomes more tilted instead of being parallel to the surface, and the butyl groups on half of the cations become more extended to have better interaction with the surface which can explain the stability gain.

Figure 5. Adsorption energy (per ion pair) vs coverage (ion pair per nm2) for the most stable type I (BMP-cis-TFSA-4) and type II (BMP-cis-TFSA-4: before and after annealing) structures of the [BMP][TFSA] monolayer on graphite basal plane. For each structure inset, upper picture is top view and lower picture is side view.

Figure 5 further shows that our type II model is much more stable than the previously suggested type I model.26 The row-like type I model is proposed based on the experimental STM images.26 Our present work showed that the checker-board structure (type II) is more stable and its STM image is expected to be quite different that of the row-like model, so it may be possible to identify the checker-board structure if it is intentionally searched for in STM.


9


Page 10 of 19

We found that the stabilization of the checker-board model is mainly due to the strengthening of the IL-graphite interaction. The tilted rings of cations in the type II structure allows the methyl and butyl groups attached to N of the cation to have stronger interaction with the surface. Similarly, the adaptation of the anion conformation also strengthens the anion-surface interactions in the type II structure. One can see that the anion and the substrate are much closer in the type II model than in the type I model (Figure 5; see also the average heights of the ions above the surface in Table S4). To compare the cation-anion interactions in the two models, we removed the substrate and calculated the energy of the IL layer frozen in the self-assembly cell and found that the difference between two types of models is < 0.1 eV per ion pair. Hence the preference of the type II structure stems mainly from the stronger cation-surface and anion-surface interactions. Below we further analyze the ion-surface interactions from the electron-density perspective.

Figure 6. Electron density difference for the two most stable SAM structures of the [BMP][TFSA] IL on graphite: (a) type I (BMP-cis-TFSA-4); (b) type II (BMP-cis-TFSA-4) after annealing.


10

Page 11 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Upper picture, top view; lower, side view. The isosurface values at ±0.0004 au; red and blue represent electron accumulation and depletion, respectively.

Electron density difference (EDD) analysis. To understand the changes of electron density distribution between the ionic liquids and the substrate after the self-assembly, we mapped the EDD plots for the two models on graphite. The EDD was defined as  (r )   (r )  graphite (r )   ILs (r )

(2)

where ρ, ρgraphite, and ρILs are the electronic densities of the IL/graphite, graphite, and the IL layer, respectively. Figure 6 compares the EDD maps of the most stable type I (BMP-cis-TFSA-4) and type II (BMP-cis-TFSA-4) structures. The red and blue isosurfaces represent electron accumulation and depletion, respectively. For the type I model (Figure 6a), one can see that electron density redistribution takes place mainly between the cations and the surface. In contrast, both cations and anions are affecting the electron density distribution in the substrate in the type II structure (Figure 6b): the electron density is augmented and the surface becomes negatively charged underneath the cation, while the electron density is depleted and the surface becomes positively charged underneath the anion. So the EDD maps further corroborate the much more ionsurface interactions, especially between the anions and the surface, in the type II structure. Independent gradient model (IGM) analysis. The non-bonded interactions between the ions and the graphite surface in our model structures can also be visualized by other methods. The noncovalent interaction (NCI) index was recently developed by Yang and coworkers for the visualization of noncovalent interactions.48 More recently, Lefebvre and coworkers developed a new electron density gradient (ρ) based approach, the independent gradient model (IGM), to identify and isolate the interactions between molecules or, more generally, between user-defined


11


Page 12 of 19

fragments.49 A key descriptor in this approach is δg = |ρIGM| - |ρ|. We have applied the δg analysis to the two most stable SAM structures of the [BMP][TFSA] IL on graphite (Figure 7) by employing the Multiwfn 3.5 software.50 Figure 7a,b shows the color-coded δg isosurfaces (for the interactions between ions and the surface, δginter) for the two most stable SAM structures of the [BMP][TFSA] IL on graphite. Blue suggests strong attractive interaction, red the steric repulsion, and green the van der Waals (vdW) interaction. One can see that the vdW interactions dominate between ions and the surface. Figure 7c,d shows the 2D plot of δginter vs sign(λ2)ρ, where λ2 is the second eigenvalue of the electrondensity Hessian matrix. Figure 7c clearly shows the dominating cation-surface interaction (red) in the type-I model, while Figure 7d shows that both cation-surface (red) and anion-surface (blue) interactions are substantial in the type II structure.

Figure 7. The independent gradient model analysis of the ion-surface interactions of the two most stable SAM structures of the [BMP][TFSA] IL on graphite: (a) δginter isosurfaces for type I (BMP-


12

Page 13 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


cis-TFSA-4); (b) δginter isosurfaces for type II (BMP-cis-TFSA-4) after annealing; (c) δginter vs. sign(λ2)ρ for type I; (d) δginter vs. sign(λ2)ρ for type II.

Implications for the graphite/ionic-liquid interface. There have been quite many previous studies of bulk ionic liquids interfacing with graphite or other metallic surfaces. In the present case of a monolayer of ionic liquid on graphite above which is either gas phase or vacuum (as in the STM experiment26), we predict an ordered self-assembled ionic-liquid layer at the interface. But if there are more layers of ionic liquids above, the inner layer might become disordered. Previous classical MD simulations of such bulk IL/graphite interfaces have shown that is indeed the case.51

CONCLUSIONS Using dispersion-corrected density functional theory, we have compared both the previously proposed row-like model (type I) and the alternative checkerboard model (type II) of the [BMP][TFSA] monolayer on the graphite basal plane. Eight candidates for each type were considered, considering both cis- and trans-configurations of the anion. We found that the checkerboard structures are more stable than the row-like structures and the anions prefer the cisconfiguration in the monolayer. We further used classical molecular dynamics simulations to perform simulated annealing on the most structure and found that the checkerboard configuration survived such a process. Optimized geometries showed that the cations are close to the surface in both types of models, but the anions are further away from the surface in the row-like model, while they are close to the surface in the checkerboard type. Charge-density-difference and noncovalentinteraction analyses confirmed the stronger anion-surface interactions in the checkerboard structures. Our work suggests that the checkerboard structure is a more viable model for the


13


Page 14 of 19

[BMP][TFSA] monolayer on the graphite basal plane.

Supporting Information Unit cell dimensions; force field parameters; average ion heights of the [BMP][TFSA] IL on graphite.

ACKNOWLEDGMENT This research is sponsored by the Fluid Interface Reactions, Structures, and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC0205CH11231. S.Z. was supported by a scholarship from the China Scholar Council.

REFERENCES (1) Etacheri, V.; Marom, R.; Elazari, R.; Salitra, G.; Aurbach, D. Challenges in the Development of Advanced Li-ion Batteries: a Review. Energy Environ. Sci. 2011, 4, 3243-3262. (2) Lin, R.; Taberna, P.-L.; Fantini, S.; Presser, V.; Pérez, C. R.; Malbosc, F.; Rupesinghe, N. L.; Teo, K. B.; Gogotsi, Y.; Simon, P. Capacitive Energy Storage from -50 to 100 C Using an Ionic Liquid Electrolyte. J. Phys. Chem. Lett. 2011, 2, 2396-2401. (3) Wei, L.; Sevilla, M.; Fuertes, A. B.; Mokaya, R.; Yushin, G. Polypyrrole-derived Activated Carbons for High-performance Electrical Double-layer Capacitors with Ionic Liquid Electrolyte. Adv. Funct. Mater. 2012, 22, 827-834. (4) Chandan, A.; Hattenberger, M.; El-Kharouf, A.; Du, S.; Dhir, A.; Self, V.; Pollet, B. G.; Ingram, A.; Bujalski, W. High Temperature (HT) Polymer Electrolyte Membrane Fuel Cells (PEMFC)–a Review. J. Power Sources 2013, 231, 264-278. (5) Tsai, W.-Y.; Lin, R.; Murali, S.; Zhang, L. L.; McDonough, J. K.; Ruoff, R. S.; Taberna, P.-L.; Gogotsi, Y.; Simon, P. Outstanding Performance of Activated Graphene based Supercapacitors in Ionic


14

Page 15 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Liquid Electrolyte from− 50 to 80 C. Nano Energy 2013, 2, 403-411. (6) Armand, M.; Tarascon, J.-M. Building Better Batteries. Nature 2008, 451, 652-657. (7) Armand, M.; Endres, F.; MacFarlane, D.; Ohno, H.; Scrosati, B. Ionic-liquid Materials for the Electrochemical Challenges of the Future. Nature Mater. 2009, 8, 621-629. (8) Baldelli, S. Probing Electric Fields at the Ionic Liquid-Electrode Interface Using Sum Frequency Generation Spectroscopy and Electrochemistry. J. Phys. Chem. B 2005, 109, 13049-13051. (9) Reed, S. K.; Lanning, O. J.; Madden, P. A. Electrochemical Interface between an Ionic Liquid and a Model Metallic Electrode. J. Chem. Phys. 2007, 126, 084704. (10) Oldham, K. B. A Gouy-Chapman-Stern Model of the Double Layer at a (Metal)/(Ionic Liquid) interface. J. Electroanal. Chem. 2008, 613, 131-138. (11) Simon, P.; Gogotsi, Y. Materials for Electrochemical Capacitors. Nature Mater. 2008, 7, 845-854. (12) Su, Y. Z.; Fu, Y. C.; Wei, Y. M.; Yan, J. W.; Mao, B. W. The Electrode/Ionic Liquid Interface: Electric Double Layer and Metal Electrodeposition. ChemPhysChem 2010, 11, 2764-2778. (13) Binnig, G.; Rohrer, H. Scanning Tunneling Microscopy. Surf. Sci. 1983, 126, 236-244. (14) Binnig, G.; Quate, C. F.; Gerber, C. Atomic Force Microscope. Phys. Rev. Lett. 1986, 56, 930. (15) Zhang, J.; Chen, P.; Yuan, B.; Ji, W.; Cheng, Z.; Qiu, X. Real-space Identification of Intermolecular Bonding with Atomic Force Microscopy. Science 2013, 342, 611-614. (16) Atkin, R.; El Abedin, S. Z.; Hayes, R.; Gasparotto, L. H.; Borisenko, N.; Endres, F. AFM and STM Studies on the Surface Interaction of [BMP] TFSA and [EMIm] TFSA Ionic Liquids with Au (111). J. Phys. Chem. C 2009, 113, 13266-13272. (17) Endres, F.; Höfft, O.; Borisenko, N.; Gasparotto, L. H.; Prowald, A.; Al-Salman, R.; Carstens, T.; Atkin, R.; Bund, A.; El Abedin, S. Z. Do Solvation Layers of Ionic Liquids Influence Electrochemical Reactions? Phys. Chem. Chem. Phys. 2010, 12, 1724-1732. (18) Drüschler, M.; Borisenko, N.; Wallauer, J.; Winter, C.; Huber, B.; Endres, F.; Roling, B. New Insights into the Interface between a Single-crystalline Metal Electrode and an Extremely Pure Ionic Liquid: Slow Interfacial Processes and the Influence of Temperature on Interfacial Dynamics. Phys. Chem. Chem. Phys. 2012, 14, 5090-5099. (19) Gnahm, M.; Berger, C.; Arkhipova, M.; Kunkel, H.; Pajkossy, T.; Maas, G.; Kolb, D. M. The Interfaces of Au (111) and Au (100) in a Hexaalkyl-substituted Guanidinium Ionic Liquid: an Electrochemical and in situ STM Study. Phys. Chem. Chem. Phys. 2012, 14, 10647-10652. (20) Buchner, F.; Forster-Tonigold, K.; Uhl, B.; Alwast, D.; Wagner, N.; Farkhondeh, H.; Groß, A.; Behm, R. J. Toward the Microscopic Identification of Anions and Cations at the Ionic Liquid| Ag (111) Interface: A Combined Experimental and Theoretical Investigation. ACS Nano 2013, 7, 7773-7784. (21) Uhl, B.; Cremer, T.; Roos, M.; Maier, F.; Steinrück, H.-P.; Behm, R. J. At the Ionic Liquid| Metal


15


Page 16 of 19

Interface: Structure Formation and Temperature Dependent Behavior of an Ionic Liquid Adlayer on Au (111). Phys. Chem. Chem. Phys. 2013, 15, 17295-17302. (22) Carstens, T.; Gustus, R.; Höfft, O.; Borisenko, N.; Endres, F.; Li, H.; Wood, R. J.; Page, A. J.; Atkin, R. Combined STM, AFM, and DFT Study of the Highly Ordered Pyrolytic Graphite/1-octyl-3methyl-imidazolium Bis (trifluoromethylsulfonyl) imide Interface. J. Phys. Chem. C 2014, 118, 1083310843. (23) Buchner, F.; Bozorgchenani, M.; Uhl, B.; Farkhondeh, H.; Bansmann, J.; Behm, R. J. Reactive Interaction of (Sub-) monolayers and Multilayers of the Ionic Liquid 1-Butyl-1-methylpyrrolidinium Bis (trifluoro-methylsulfonyl) imide with Coadsorbed Lithium on Cu (111). J. Phys. Chem. C 2015, 119, 16649-16659. (24) Elbourne, A.; McDonald, S.; Voïchovsky, K.; Endres, F.; Warr, G. G.; Atkin, R. Nanostructure of the Ionic Liquid–graphite Stern Layer. ACS Nano 2015, 9, 7608-7620. (25) Wen, R.; Rahn, B.; Magnussen, O. M. Potential-dependent Adlayer Structure and Dynamics at the Ionic Liquid/Au (111) Interface: A molecular-scale in Situ Video-STM Study. Angew. Chem. Int. Ed. 2015, 54, 6062-6066. (26) Buchner, F.; Forster-Tonigold, K.; Bozorgchenani, M.; Gross, A.; Behm, R. J. Interaction of a Selfassembled Ionic Liquid Layer with Graphite (0001): A Combined Experimental and Theoretical Study. J. Phys. Chem. Lett. 2016, 7, 226-233. (27) Carstens, T.; Ispas, A.; Borisenko, N.; Atkin, R.; Bund, A.; Endres, F. In Situ Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and Quartz Crystal Microbalance (EQCM) Studies of the Electrochemical Deposition of Tantalum in two Different Ionic Liquids with the 1-butyl-1methylpyrrolidinium Cation. Electrochim. Acta 2016, 197, 374-387. (28) Blanco, J. M.; González, C.; Jelínek, P.; Ortega, J.; Flores, F.; Pérez, R. First-principles Simulations of STM Images: from Tunneling to the Contact Regime. Phys. Rev. B 2004, 70, 085405. (29) Valencia, H.; Kohyama, M.; Tanaka, S.; Matsumoto, H. Ab Initio Study of EMIM-BF 4 Molecule Adsorption on Li Surfaces as a Model for Ionic Liquid/Li Interfaces in Li-ion Batteries. Phys. Rev. B 2008, 78, 205402. (30) Casarin, M.; Marino, M. D.; Forrer, D.; Sambi, M.; Sedona, F.; Tondello, E.; Vittadini, A.; Barone, V.; Pavone, M. Coverage-dependent Architectures of Iron Phthalocyanine on Ag (110): A Comprehensive STM/DFT Study. J. Phys. Chem. C 2010, 114, 2144-2153. (31) Donovan, P.; Robin, A.; Dyer, M. S.; Persson, M.; Raval, R. Unexpected Deformations Induced by Surface Interaction and Chiral Self-assembly of CoII-tetraphenylporphyrin (Co-TPP) Adsorbed on Cu (110): a Combined STM and Periodic DFT Study. Chem. Eur. J. 2010, 16, 11641-11652. (32) Valencia, H.; Kohyama, M.; Tanaka, S.; Matsumoto, H. First-principles Study of EMIM-FAFSA


16

Page 17 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Molecule Adsorption on a Li (100) Surface as a Model for Li-ion Battery Electrodes. J. Phys. Chem. C 2012, 116, 8493-8509. (33) Martínez-Galera, A. J.; Nicoara, N.; Martínez, J. I.; Dappe, Y. J.; Ortega, J.; Gómez-Rodríguez, J. M. Imaging Molecular Orbitals of PTCDA on Graphene on Pt (111): Electronic Structure by STM and First-principles Calculations. J. Phys. Chem. C 2014, 118, 12782-12788. (34) Lu, Y.; Zhang, S.; Peng, C.; Liu, H. Interplay Between Halogen and Hydrogen Bonds in 2D Selfassembly on the Gold Surface: A First-principles Investigation. J. Phys. Chem. C 2017, 121, 24707-24720. (35) Zhang, S.; Lu, Y.; Zhang, Y.; Peng, C.; Liu, H. Halogen-bond-based Molecular Self-Assembly on Graphene Surface: A First-principles Study. J. Phys. Chem. C 2017, 121, 4451-4461. (36) Kresse, G.; Hafner, J. Ab Initio Molecular Dynamics for Liquid Metals. Phys. Rev. B 1993, 47, 558-561. (37) Kresse, G.; Hafner, J. Ab Initio Molecular-dynamics Simulation of the Liquid-metal–amorphoussemiconductor Transition in Germanium. Phys. Rev. B 1994, 49, 14251-14269. (38) Kresse, G.; Furthmüller, J. Efficient Iterative Schemes for Ab Initio Total-energy Calculations Using a Plane-wave Basis Set. Phys. Rev. B 1996, 54, 11169-11186. (39) Kresse, G.; Furthmüller, J. Efficiency of Ab-initio Total Energy Calculations for Metals and Semiconductors Using a Plane-wave Basis Set. Comp. Mater. Sci. 1996, 6, 15-50. (40) Kresse, G.; Joubert, D. From Ultrasoft Pseudopotentials to the Projector Augmented-wave Method. Phys. Rev. B 1999, 59, 1758-1775. (41) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865-3868. (42) Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. A Consistent and Accurate Ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu. J. Chem. Phys. 2010, 132, 154104. (43) Becke, A. D.; Johnson, E. R. Exchange-hole Dipole Moment and the Dispersion Interaction. J. Chem. Phys. 2005, 122, 154104. (44) Grimme, S.; Ehrlich, S.; Goerigk, L. Effect of the Damping Function in Dispersion Corrected Density Functional Theory. J. Comput. Chem. 2011, 32, 1456-1465. (45) Plimpton, S. Fast Parallel Algorithms for Short-range Molecular Dynamics. J. Comput. Phys. 1995, 117, 1-19. (46) Dauber-Osguthorpe, P.; Roberts, V. A.; Osguthorpe, D. J.; Wolff, J.; Genest, M.; Hagler, A. T. Structure and Energetics of Ligand Binding to Proteins: Escherichia Coli Dihydrofolate Reductasetrimethoprim, a Drug-receptor System. Proteins: Struct. Funct. Genet. 1988, 4, 31-47. (47) Borodin, O.; Smith, G. D. Structure and Dynamics of N-methyl-N-propylpyrrolidinium Bis


17


Page 18 of 19

(trifluoromethanesulfonyl) imide Ionic Liquid from Molecular Dynamics Simulations. J. Phys. Chem. B 2006, 110, 11481-11490. (48) Johnson, E. R.; Keinan, S.; Mori-Sanchez, P.; Contreras-Garcia, J.; Cohen, A. J.; Yang, W. Revealing Noncovalent Interactions. J. Am. Chem. Soc. 2010, 132, 6498-6506. (49) Lefebvre, C.; Rubez, G.; Khartabil, H.; Boisson, J.-C.; Contreras-García, J.; Hénon, E. Accurately Extracting the Signature of Intermolecular Interactions Present in the NCI plot of the Reduced Density Gradient versus Electron Density. Phys. Chem. Chem. Phys. 2017, 19, 17928-17936. (50) Lu, T.; Chen, F. Multiwfn: a Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33, 580-592. (51) Yokota, Y.; Miyamoto, H.; Imanishi, A.; Inagaki, K.; Morikawa, Y.; Fukui, K.-i. Structural and Dynamic Properties of 1-Butyl-3-Methylimidazolium Bis(Trifluoromethanesulfonyl)Imide/Mica and Graphite Interfaces Revealed by Molecular Dynamics Simulation. Phys. Chem. Chem. Phys. 2018, 20, 6668-6676.


18

Page 19 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


TOC Graphic


19

Structure and Interaction of Ionic Liquid Monolayer on Graphite from

Recommend Documents