Rational Design of Stable Dianions and the Concept of Super-Chalcogens.

Super-atoms are homo/heteroatomic clusters that mimic the chemistry of atoms in the periodic table. While a considerable amount of research over the past three decades has revealed many super-atoms that mimic group I (alkali metals) and group 17 (halogens) elements, little effort has been made to identify super-atoms that mimic the chemistry of chalcogens, i.e.

Colossal Stability of Gas-Phase Trianions: Super-Pnictogens.

Multiply charged negative ions are ubiquitous in nature. They are stable as crystals because of charge compensating cations; while in solutions, solvent molecules protect them. However, they are rarely stable in the gas phase because of strong electrostatic repulsion between the extra electrons.

Modulating the phases of iron carbide nanoparticles: from a perspective of interfering with the carbon penetration of Fe@FeO by selectively adsorbed halide ions.

Iron carbide nanoparticles (ICNPs) are considered to have great potential in new energy conversion, nanomagnets and biomedical applications due to their intrinsically peculiar magnetic and catalytic properties. However, the synthetic routes were greatly limited in morphology and phase controlled synthesis. In this article, we present a versatile solution chemistry route towards colloidal ICNPs (FeC-hexagonal and monoclinic syngony, FeC-monoclinic syngony and FeC-orthorhombic syngony) derived from body centered cubic Fe@FeO by introducing heteroatoms to restrain their phase transformation.

Rational design of super-alkalis and their role in CO activation.

Super-alkalis are clusters of atoms. With ionization potentials smaller than those of the alkali atoms, they are playing an increasing role in chemistry as highlighted by recent applications in solar cells as well as in Li-ion batteries. For the past 40 years superalkalis were designed using inorganic elements with the sp orbital character.

Ferromagnetic and Half-Metallic FeC Monolayer Containing C Dimers.

Ferromagnetism and half-metallicity are two vital properties of a material for realizing its potential in spintronics applications. However, none of the two-dimensional (2D) pristine metal-carbide sheets synthesized experimentally exhibits half-metallicity with ferromagnetic coupling. Here, a ferromagnetic and half-metallic FeC sheet containing isolated C dimers rather than individual carbon atoms is predicted to be such a material.

Like Charges Attract?

Using multiscale first-principles calculations, we show that two interacting negatively charged B12I9(-) monoanions not only attract, in defiance of the Coulomb's law, but also the energy barrier at 400 K is small enough that these two moieties combine to form a stable B24I18(2-) moiety. Ab initio molecular dynamics simulations further confirm its stability up to 1500 K. Studies of other B12X9(-) (X = Br, Cl, F, H, Au, CN) show that while all of these B24X18(2-) moieties are stable against dissociation, the energy barrier, with the exception of B24Au18(2-), is large so as to hinder their experimental observation.

Thermal exfoliation of stoichiometric single-layer silica from the stishovite phase: insight from first-principles calculations.

Mechanical cleavage, chemical intercalation and chemical vapor deposition are the main methods that are currently used to synthesize nanosheets or monolayers. Here, we propose a new strategy, thermal exfoliation for the fabrication of silica monolayers. Using a variety of state-of-the-art theoretical calculations we show that a stoichiometric single-layer silica with a tetragonal lattice, T-silica, can be thermally exfoliated from the stishovite phase in a clean environment at room temperature.

TiC2: a new two-dimensional sheet beyond MXenes.

MXenes are attracting attention due to their rich chemistry and intriguing properties. Here a new type of metal-carbon-based sheet composed of transition metal centers and C2 dimers rather than individual C atom is designed. Taking the Ti system as a test case, density functional theory calculations combined with a thermodynamic analysis uncover the thermal and dynamic stability of the sheet, as well as a metallic band structure, anisotropic Young's modulus and Poisson's ratio, a high heat capacity, and a large Debye stiffness.

Tuning electronic and magnetic properties of silicene with magnetic superhalogens.

Due to its compatibility with the well-developed Si-based semiconductor industry, silicene has attracted considerable attention. Using density functional theory we show for the first time that the recently synthesized superhalogen MnCl3 can be used to tune the electronic and magnetic properties of silicene, from semi-metallic to semiconducting with a wide range of band gaps, as well as from nonmagnetic to ferromagnetic (or antiferromagnetic) by changing the coverage of the superhalogen molecules. The electronic properties can be further modulated when a superhalogen and a halogen are used synergistically.

Robust ferromagnetism in monolayer chromium nitride.

Design and synthesis of two-dimensional (2D) materials with robust ferromagnetism and biocompatibility is highly desirable due to their potential applications in spintronics and biodevices. However, the hotly pursued 2D sheets including pristine graphene, monolayer BN, and layered transition metal dichalcogenides are nonmagnetic or weakly magnetic. Using biomimetic particle swarm optimization (PSO) technique combined with ab initio calculations we predict the existence of a 2D structure, a monolayer of rocksalt-structured CrN (100) surface, which is both ferromagnetic and biocompatible.

All-metal clusters that mimic the chemistry of halogens.

Owing to their s(2)p(5) electronic configuration, halogen atoms are highly electronegative and constitute the anionic components of salts. Whereas clusters that contain no halogen atoms, such as AlH(4), mimic the chemistry of halogens and readily form salts (e.g.