Assembling Au4 Tetrahedra to 2D and 3D Superatomic Crystals Based on Superatomic-Network Model.

Thiolate-protected gold nanoclusters (denoted as Au m (SR) n or Au n L m ) have received extensive attention both experimentally and theoretically. Understanding the growth mode of the Au4 unit in Au m (SR) n is of great significance for experimental synthesis and the search for new gold clusters. In this work, we first build six clusters of Au7(AuCl2)3, Au12(AuCl2)4, Au16(AuCl2)6, Au22(AuCl2)6, and Au30(AuCl2)6 with the Au4 unit as the basic building blocks. Density functional theory (DFT) calculations show that these newly designed clusters have high structural and electronic stabilities. Based on chemical bonding analysis, the electronic structures of these clusters follow the superatom network (SAN) model. Inspired by the cluster structures, we further predicted an Au4 two-dimensional (2D) monolayer and a three-dimensional (3D) crystal using graphene and diamond as templates, respectively. The computational results demonstrate that the two structures have high dynamic, thermal, and mechanical stabilities, and both structures exhibit metallic properties according to the band structures calculated at the HSE06 level. The chemical bonding analysis by the solid-state natural density partitioning (SSAdNDP) method indicates that they are superatomic crystals assembled by two electron Au4 - superatoms. With this construction strategy, the new bonding pattern and properties of Au n L m are studied and the structure types of gold are enriched.

FeP2 monolayer: isoelectronic analogue of MoS2 with excellent electronic and optical properties.

Two-dimensional semiconductors with suitable indirect band gaps, excellent light absorption capacity, and oxidation resistance are particularly suitable for material applications. Here based on first-principle calculations, we report that the FeP2 monolayer, which is isoelectronic with MoS2, has novel electronic properties and an ultra-low diffusion energy barrier of K on the surface, indicating its potential as an anode material of K-ion batteries. The calculated phonon dispersion curves, molecular dynamics, and elastic constants showed that it has high structural stability and oxidation resistance. The monolayer was a semiconductor with an indirect band gap of 0.68 eV. In addition, the FeP2 monolayer had obvious light absorption in the infrared, visible, and ultraviolet regions, which can be widely used in optoelectronic devices. Bonding analysis showed that there were multicenter bonds inside every hexagonal ring. As the anode material of K-ion batteries, the FeP2 monolayer had a capacity of 456.84 mA h g-1, low diffusion energy barrier, and open-circuit voltage. All these characteristics suggest that the FeP2 monolayer is a potential anode material for K-ion batteries, which needs to be further verified by experiments.

Tri- and Tetra-superatomic Molecules in Ligand-Protected Face-Fused Icosahedral (M@Au12)n (M = Au, Pt, Ir, and Os, and n = 3 and 4) Clusters.

Cluster assembling has been one of the hottest topics in nanochemistry. In certain ligand-protected gold clusters, bi-icosahedral cores assembled from Au13 superatoms were found to be analogues of diatomic molecules F2, N2, and singlet O2, respectively, in electronic shells, depending upon the super valence bond (SVB) model. However, challenges still remain for extending the scale in cluster assembling via the SVB model. In this work, ligand-protected tri- and tetra-superatomic clusters composed of icosahedral M@Au12 (M = Au, Pt, Ir, and Os) units are theoretically predicted. These clusters are stable with reasonable highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps and proven to be analogues of simple triatomic (Cl3-, OCl2, O3, and CO2) and tetra-atomic (N≡C-C≡N, and Cl-C≡C-Cl) molecules in both geometric and electronic structures. Moreover, a stable cluster-assembling gold nanowire is predicted following the same rules. This work provides effective electronic rules for cluster assembling on a larger scale and gives references for their experimental synthesis.

Formulating Multiphase Medium Anti-wetting States in an Air-Water-Oil System: Engineering Defects for Interface Chemical Evolutions.

Studies which regulate macroscopic wetting states on determined surfaces in multiphase media are of far-reaching significance but are still in the preliminary stage. Herein, inspired by the wettability subassembly of fish scales, Namib desert beetle shell, and lotus leaf upper side, interfaces in the air-water-oil system are programmed by defect engineering to tailor the anti-wetting evolution from double to triple liquid repellency states. By controlling the visible light irradiation and plasma treatment, surface oxygen vacancies on CuxO@TiO2 nanowires (NWs) can be healed or reconstructed. The original membrane or the membrane after plasma treatment possesses abundant surface oxygen vacancies, and the homogeneous hydrophilic membrane shows only double anti-wetting states in the water-oil system. By the unsaturated visible light irradiation time, the surface oxygen vacancy partially healed, the heterogeneous hydrophilic-hydrophobic components occupied the membrane surface, and the anti-wetting state finally changed from double to triple in the air-water-oil system. After the illumination time reaches saturation, it promotes the healing of all surface oxygen vacancies, and the membrane surface only contains uniform hydrophobic components and only maintains double anti-wetting state in the air-oil system. The mechanism of the triple anti-wetting state on a heterogeneous surface is expounded by establishing a wetting model. The wetting state and the adhesion state of the CuxO@TiO2 NW membrane show regional specificity by controlling the illumination time and region. The underwater oil droplets exhibit the "non-adhesive" and "adhesive" state in a region with unsaturated irradiation time or in an unirradiated region, respectively. Underwater oil droplet manipulation can be accomplished easily based on switchable wettability and adhesion. Current studies reveal that defect engineering can be extended to anti-wetting evolution in the air-water-oil system. Constructing an anti-wetting interface by heterogeneous components provides reference for designing the novel anti-wetting interface.

Prediction of an Al4C4 superatom organic framework (SOF) material based on the superatom network model.

Metal organic framework (MOF) materials have attracted significant attention due to their wide potential applications, but it is still a challenge to design MOFs with advanced properties by exploring novel metal nodes. In this study, a kind of superatom organic framework (SOF) material is proposed based on the superatom network (SAN) model. Tetrahedron Al4 superatom unit is used as nodes in the MOF structure, and linear -CC- ligands are chosen as linkers. Localized chemical bonding analysis and nucleus-independent chemical shift (NICS) scan confirm that the Al4 core keeps the superatom electronic shell in the SOF structure. Further calculations demonstrate that this Al4C4 crystal has high dynamic and thermal stabilities, with an indirect semiconductor band gap of 2.57 eV. Analysis of its optical properties indicates its potential applications as an optoelectronic device. This novel kind of SOF material has both porous framework as traditional MOFs and superatomic character in its nodes, indicating its unique potential properties. Our work would provide a new way for designing functional MOF materials.