A semiconductor Sc2S3 monolayer with ultrahigh carrier mobility for UV blocking filter application.

For humans, ultraviolet (UV) light from sun is harmful to our eyes and eye-related cells. This detrimental fact requires scientists to search for a material that can efficiently absorb UV light while allowing lossless transmission of visible light. Using an unbiased first-principles swarm intelligence structure search, we explored two-dimensional (2D) Sc-S crystals and identified a novel Sc2S3 monolayer with good thermal and dynamical stability. The optoelectronic property simulations revealed that the Sc2S3 monolayer has a wide indirect bandgap (3.05 eV) and possesses an ultrahigh carrier mobility (2.8 × 103 cm2 V-1 s-1). Remarkably, it has almost transparent visible light absorption, while it exhibits an ultrahigh absorption coefficient up to × 105 cm-1 in the ultraviolet region. Via the application of biaxial strain and thickness modulation, the UV light absorption coefficients of Sc2S3 can be further improved. These findings manifest an attractive UV blocking optoelectronic characteristic of the Sc2S3 configuration as a prototypical nanomaterial for the potential application in UV blocking filters.

Unveiling Interstitial Anionic Electron-Driven Ultrahigh K-Ion Storage Capacity in a Novel Two-Dimensional Electride Exemplified by Sc3Si2.

Two-dimensional (2D) electrides, characterized by excess interstitial anionic electron (IAE) in a crystalline 2D material, offer promising opportunities for the development of electrode materials, in particular in rechargeable metal-ion batteries applications. Although a few such potential electride materials have been reported, they generally show low metal-ion storage capacity, and the effect of IAE on the ion storage performance remains elusive so far. Here we report a novel 2D electride, [Sc3Si2]1+·1e-, with fascinating IAE-driven high alkali metal-ion storage capacity. In particular, its K-ion specific capacity can reach up to 1497 mA h g-1, higher than any previously reported 2D materials-based anodes in K-ion batteries (PIBs). The IAE in the [Sc3Si2]1+·1e- crystal accounts for such high capacity behavior, which can drift away and balance the charge on the metal-cation, playing a crucial role in stabilizing the metal-ion adsorption and enhancing multilayer-ions adsorption. This proposed IAE-driven storage mechanism provides an unprecedented avenue for the future design of high storage capacity electrode materials.

Exploring a novel two-dimensional metallic Y4C3 sheet applied as an anode material for sodium-ion batteries.

As novel "post lithium-ion batteries" and promising alternatives to lithium-ion batteries (LIBs) suffering from the limited Li resources, sodium-ion batteries (SIBs) are nowadays emerging and show bright prospects in large-scale energy storage applications due to abundant Na resources. However, a lack of suitable anode materials has become a key obstacle for the development of SIBs. Here we explore the potential of the two-dimensional (2D) Y-C space and identify a novel anode material for SIBs, a new Y4C3 sheet with P3̄m1 crystal symmetry, by means of first-principles swarm structure calculations. This Y4C3P3̄m1 structure has rather good kinetic and thermodynamic stability, possesses intrinsic metallicity, and remains metallic after adsorbing Na atoms, ensuring good electrical conductivity during the SIB cycle. Remarkably, a Y4C3 sheet as an anode for SIBs possesses the essential properties of a high specific capacity (∼752 mA h g-1), a low barrier energy (∼0.1 eV), and suitable open-circuit voltage (0-0.15 V). These characteristics are comparable and even superior to those of another known 2D Y2C anode material, indicating that the Y4C3 sheet can act as an appealing new candidate as an anode material for SIBs and offering new insights into the 2D Y-C space.

2D auxetic material with intrinsic ferromagnetism: a copper halide (CuCl2) monolayer.

The discovery of ferromagnetism in monolayer transition metal halides exemplified by CrI3 has opened a new avenue in the field of two-dimensional (2D) magnetic materials, and more such 2D materials are waiting to be explored. Herein, using an unbiased structure search combined with first-principles calculations, we have identified a novel CuCl2 monolayer, which exhibits not only intrinsic ferromagnetism but also auxetic mechanical properties originating from the interplay of lattice and Cu-Cl tetrahedron symmetries. The predicted Curie temperature of CuCl2 reaches ∼47 K, and its ferromagnetism is associated with the strong hybridization between the Cu 3d and Cl 3p states in the configuration. Moreover, upon biaxial tensile strain or carrier doping, the CuCl2 monolayer can be converted from ferromagnetic to non-magnetic and from half-metal to metal. These properties endow this CuCl2 monolayer with great potential for applications in auxetic/spintronic nanodevices.