Title Participants Abstract "Chlorinated phosphorene for energy application" "Nasim Hassani, Mehmet Yagmurcukardes, Francois Peeters, Mehdi Neek-Amal" "The influence of decoration with impurities and the composition dependent band gap in 2D materials has been the subject of debate for a long time. Here, by using Density Functional Theory (DFT) calculations, we systematically disclose physical properties of chlorinated phosphorene having the stoichiometry of PmCln. By analyzing the adsorption energy, charge density, migration energy barrier, structural, vibrational, and electronic properties of chlorinated phosphorene, we found that (I) the Cl-P bonds are strong with binding energy Eb =-1.61 eV, decreases with increasing n. (II) Cl atoms on phosphorene have anionic feature, (III) the migration path of Cl on phosphorene is anisotropic with an energy barrier of 0.38 eV, (IV) the phonon band dispersion reveal that chlorinated phosphorenes are stable when r" "Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction" "M. Mirzakhani, N. Myoung, Francois Peeters, H.C. Park" "Graphene matter in a strong magnetic field, realizing one-dimensional quantum Hall channels, provides a unique platform for studying electron interference. Here, using the Landauer-Buttiker formalism along with the tightbinding model, we investigate the quantum Hall (QH) effects in unipolar and bipolar monolayer-bilayer graphene (MLG-BLG) junctions. We find that a Hall bar made of an armchair MLG-BLG junction in the bipolar regime results in valley-polarized edgechannel interferences and can operate a fully tunable Mach-Zehnder (MZ) interferometer device. Investigation of the bar-width and magnetic-field dependence of the conductance oscillations shows that the MZ interference in such structures can be drastically affected by the type of (zigzag) edge termination of the second layer in the BLG region [composed of vertical dimer or non-dimer atoms]. Our findings reveal that both interfaces exhibit a double set of Aharonov-Bohm interferences, with the one between two oppositely valley-polarized edge channels dominating and causing a large amplitude conductance oscillation ranging from 0 to 2e2/h. We explain and analyze our findings by analytically solving the Dirac-Weyl equation for a gated semi-infinite MLG-BLG junction." "Multiband flattening and linear Dirac band structure in graphene with impurities" "S. Ahmadkhani, M. Alihosseini, S. Ghasemi, I. Ahmadabadi, N. Hassani, Francois Peeters, M. Neek-Amal" "Flat bands in the energy spectrum have attracted a lot of attention in recent years because of their unique properties and promising applications. Special arrangement of impurities on monolayer graphene are proposed to generate multiflat bands in the electronic band structure. In addition to the single midgap states in the spectrum of graphene with low hydrogen density, we found closely spaced bands around the Fermi level with increasing impurity density, which are similar to discrete lines in the spectrum of quantum dots, as well as the unusual Landau-level energy spectrum of graphene in the presence of a strong magnetic field. The presence of flat bands crucially depends on whether or not there are odd or even electrons of H(F) atoms bound to graphene. Interestingly, we found that a fully hydrogenated (fluoridated) of a hexagon of graphene sheet with six hydrogen (fluorine) atoms sitting on top and bottom in consecutive order exhibits Dirac cones in the electronic band structure with a 20% smaller Fermi velocity as compared to the pristine graphene. Functionalizing graphene introduces various C-C bond lengths resulting in nonuniform strains. Such a nonuniform strain may induce a giant pseudomagnetic field in the system, resulting in quantum Hall effect." "Strain engineering of hyperbolic plasmons in monolayer carbon phosphide" "Mahyar Dehdast, Mehdi Neek-Amal, Catherine Stampfl, Mahdi Pourfath" "Natural and tunable in-plane hyperbolic plasmons have so far been elusive, and hence few two-dimensional hyperbolic materials have been theoretically and experimentally discovered. Here, comprehensive first-principles calculations were conducted to study the electronic and plasmonic properties of biaxially strained monolayer carbon phosphide (beta-CP). We found that (i) a compressed beta-CP hosts strong anisotropic Dirac-shaped fermions with robust modulated Fermi velocity, (ii) for biaxial strain of -3% an unprecedented ultra-wide hyperbolic window is extended continuously from terahertz (9 THz) to mid-visible (blue light, 693 THz), (iii) the tunable optical Van Hove singularity as the origin of hyperbolic plasmons in deformed beta-CP is disclosed, (iv) an elliptic to hyperbolic transition in the sigma-near-zero regime is demonstrated in terahertz frequencies (9 THz), (v) the propagation angle of the concave wavefront can be actively tuned using biaxial strains, and (vi) hyperbolic dispersion reorientation from one principal axis to another orthogonal one under compressive strains larger than 8% is observed. This study sheds new light on the unique properties of hyperbolic two-dimensional (2D) materials having exotic optoelectronic characteristics which are promising candidates for anisotropic light control with ultimate dexterity in the flat optics." "The solvent-driven impurity migration over graphene in the presence of electric field" "M. Alihosseini, F. Khoeini, Mehdi Neek-Amal" "The spontaneous migration and interconversion of oxygen functional groups over graphene sheet have promising high-tech applications. There is a remarkable activation energy barrier against epoxy movement over the graphene. To overcome this energy barrier, different methods have been proposed. In this paper, using first principles calculations, we study the effects of external electric fields and solvents on the activation energy barrier. Our findings show that: (i) epoxy migration on one side of the surface of a graphene sheet is facilitated when a hydroxyl group is adsorbed on the other side of the surface, (ii) applying a perpendicular electric field along the opposite direction of the adsorbed epoxy, weakens the corresponding C-O bonds strength and consequently decreases the activation energy barrier, (iii) the solvents with a larger dielectric constant cause decreasing the activation energy barrier, (iv) under applying an electric field for any given solution, the oxidized graphene is polarized and its solubility increases with decreasing activation energy barrier, and (v) the presence of a single vacancy in the graphene sheet, decreases the barrier. Our work reveals different physical aspects of the solubility of the oxidized graphene in the presence of electric field and vacancy defect on the surface of the graphene sheet." "Partial sulfidation of the electrochemically exfoliated layered double hydroxides toward advanced aqueous zinc batteries" "Hajar Yousefzadeh, Abolhassan Noori, Mohammad S. Rahmanifar, Nasim Hassani, Mehdi Neek-Amal, Maher F. El-Kady, Ajayan Vinu, Richard B. Kaner, Mir F. Mousavi" "Aqueous zinc-based batteries are a promising alternative to lithium batteries. These batteries, however, persistently suffer from uncontrollable dendrite growth and sustained water consumption at the Zn anodes, along with low and often fading capacity at the cathodes. Herein, Zn metal is simply encapsulated into a chitosan-containing polymer gel that not only suppresses hydrogen evolution but also enables dendrite-free Zn plating/stripping. A binder-free cathode based on the electrochemically exfoliated and partially sulfidated Ni-Co-Fe layered double hydroxide-reduced graphene oxide (SNS-rGO) nanocomposite is also reported. The fabricated devices (based on either Zn or chitosan-coated Zn) deliver near record-high values of specific capacity (756 mA h g-1cathode at 1 A g-1) and specific energy (1284 W h kg-1cathode), along with an outstanding specific power (108 kW kg-1cathode), an excellent output voltage (up to 1.9 V), and prolonged cycling stability at 100% depth-of-discharge. This interface engineering strategy, supported by the density functional theory calculations, provides a solid basis for further practical applications of aqueous Zn batteries. A stable and dendrite-free zinc anode is achieved by incorporating a chitosan-containing polymer gel as a protective coating. A facile and fast electrochemical exfoliation approach is also devised to efficiently exfoliate the layered double hydroxides into single- to few-layered 2D nanosheets. Partial sulfidation of the exfoliated nanosheets results in a cathodic active material with a near-record performance.image" "Beyond steric selectivity of ions using ångström-scale capillaries" "Solleti Goutham, Ashok Keerthi, Abdulghani Ismail, Ankit Bhardwaj, Hossein Jalali, Yi You, Yiheng Li, Nasim Hassani, Haoke Peng, Marcos Vinicius Surmani Martins, Fengchao Wang, Mehdi Neek-Amal, Boya Radha" "Ionic flow through angstrom-scale channels facilitates selectivity beyond steric effects between ions of same charge and hydrated diameter. Here, with two-dimensional channels, the authors show that ion position in the channel influences selectivity. Ion-selective channels play a key role in physiological processes and are used in many technologies. Although biological channels can efficiently separate same-charge ions with similar hydration shells, it remains a challenge to mimic such exquisite selectivity using artificial solid-state channels. Although there are several nanoporous membranes that show high selectivity with respect to certain ions, the underlying mechanisms are based on the hydrated ion size and/or charge. There is a need to rationalize the design of artificial channels to make them capable of selecting between similar-sized same-charge ions, which, in turn, requires an understanding of why and how such selectivity can occur. Here we study angstrom-scale artificial channels made by van der Waals assembly, which are comparable in size with typical ions and carry little residual charge on the channel walls. This allows us to exclude the first-order effects of steric- and Coulomb-based exclusion. We show that the studied two-dimensional angstrom-scale capillaries can distinguish between same-charge ions with similar hydrated diameters. The selectivity is attributed to different positions occupied by ions within the layered structure of nanoconfined water, which depend on the ion-core size and differ for anions and cations. The revealed mechanism points at the possibilities of ion separation beyond simple steric sieving." "Gate-controlled suppression of light-driven proton transport through graphene electrodes" "S. Huang, E. Griffin, J. Cai, B. Xin, J. Tong, Y. Fu, V. Kravets, Francois Peeters, M. Lozada-Hidalgo" "Recent experiments demonstrated that proton transport through graphene electrodes can be accelerated by over an order of magnitude with low intensity illumination. Here we show that this photo-effect can be suppressed for a tuneable fraction of the infra-red spectrum by applying a voltage bias. Using photocurrent measurements and Raman spectroscopy, we show that such fraction can be selected by tuning the Fermi energy of electrons in graphene with a bias, a phenomenon controlled by Pauli blocking of photo-excited electrons. These findings demonstrate a dependence between graphene's electronic and proton transport properties and provide fundamental insights into molecularly thin electrode-electrolyte interfaces and their interaction with light. Recent experiments have shown that proton transport through graphene electrodes can be promoted by light, but the understanding of this phenomenon remains unclear. Here, the authors report the electrical tunability of this photo-effect, showing a connection between graphene electronic and proton transport properties." "A perspective on the state-of-the-art functionalized 2D materials" "T.A. Duran, Y.O. Yayak, H. Aydin, Francois Peeters, M. Yagmurcukardes" "Two-dimensional (2D) ultra-thin materials are more crucial than their bulk counterparts for the covalent functionalization of their surface owing to atomic thinness, large surface-to-volume ratio, and high reactivity of surface atoms having unoccupied orbitals. Since the surface of a 2D material is composed of atoms having unoccupied orbitals, covalent functionalization enables one to improve or precisely modify the properties of the ultra-thin materials. Chemical functionalization of 2D materials not only modifies their intrinsic properties but also makes them adapted for nanotechnology applications. Such engineered materials have been used in many different applications with their improved properties. In the present Perspective, we begin with a brief history of functionalization followed by the introduction of functionalized 2D materials. Our Perspective is composed of the following sections: the applications areas of 2D graphene and graphene oxide crystals, transition metal dichalcogenides, and in-plane anisotropic black phosphorus, all of which have been widely used in different nanotechnology applications. Finally, our Perspectives on the future directions of applications of functionalized 2D materials are given. The present Perspective sheds light on the current progress in nanotechnological applications of engineered 2D materials through surface functionalization." "Tailoring metal-organic frameworks and derived materials for high-performance zinc-air and alkaline batteries" "Atefeh Ashoori, Abolhassan Noori, Mohammad S. Rahmanifar, Ali Morsali, Nasim Hassani, Mehdi Neek-Amal, Hosein Ghasempour, Xinhui Xia, Yongqi Zhang, Maher F. El-Kady, Richard B. Kaner, Mir F. Mousavi" "Developing multifunctional materials from earth-abundantelementsis urgently needed to satisfy the demand for sustainable energy. Herein,we demonstrate a facile approach for the preparation of a metal-organicframework (MOF)-derived Fe2O3/C, compositedwith N-doped reduced graphene oxide (MO-rGO). MO-rGO exhibits excellentbifunctional electrocatalytic activities toward the oxygen evolutionreaction (eta(j=10) = 273 mV) and the oxygen reductionreaction (half-wave potential = 0.77 V vs reversible hydrogen electrode)with a low Delta E (OER-ORR) of 0.88V in alkaline solutions. A Zn-air battery based on the MO-rGOcathode displays a high specific energy of over 903 W h kg(Zn) (-1) (similar to 290 mW h cm(-2)), anexcellent power density of 148 mW cm(-2), and an open-circuitvoltage of 1.430 V, outperforming the benchmark Pt/C + RuO2 catalyst. We also hydrothermally synthesized a Ni-MOF that was partiallytransformed into a Ni-Co-layered double hydroxide (MOF-LDH).A MO-rGO||MOF-LDH alkaline battery exhibits a specific energy of 42.6W h kg(total mass) (-1) (106.5 mu Wh cm(-2)) and an outstanding specific power of 9.8kW kg(total mass) (-1) (24.5 mW cm(-2)). This work demonstrates the potential of MOFs andMOF-derived compounds for designing innovative multifunctional materialsfor catalysis, electrochemical energy storage, and beyond."