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Studies of graphene show that robust chemical bonds such as covalent bonds with trigonal‐planar atoms afford layered atomic 2D crystals possessing unique properties. Although layered molecular crystals are of interest to diversify elements and structures of 2D materials, the structural diversity of molecules as well as weak intermolecular interactions inevitably makes the design to be one‐off and individual. We herein report a versatile method to assemble layered molecular crystals. By developing a D3‐symmetry host at vertices to form a honeycomb layer, a diverse range of layered 2D host–guest crystals were obtained. Substituents on the host, elements/structures of the guest, the stereochemistry of the host and types of intercalants were diversified, which should allow for 6×32×3×2 combinations for structural diversification. [ABSTRACT FROM AUTHOR]

Na+/vacancy ordering in sodium‐ion layered oxide cathodes is widely believed to deteriorate the structural stability and retard the Na+ diffusion kinetics, but its unexplored potential advantages remain elusive. Herein, we prepared a P2‐Na0.8Cu0.22Li0.08Mn0.67O2 (NCLMO‐12 h) material featuring moderate Na+/vacancy and transition‐metal (TM) honeycomb orderings. The appropriate Na+/vacancy ordering significantly enhances the operating voltage and the TM honeycomb ordering effectively strengthens the layered framework. Compared with the disordered material, the well‐balanced dual‐ordering NCLMO‐12 h cathode affords a boosted working voltage from 2.85 to 3.51 V, a remarkable ~20 % enhancement in energy density, and a superior cycling stability (capacity retention of 86.5 % after 500 cycles). The solid‐solution reaction with a nearly “zero‐strain” character, the charge compensation mechanisms, and the reversible inter‐layer Li migration upon sodiation/desodiation are unraveled by systematic in situ/ex situ characterizations. This study breaks the stereotype surrounding Na+/vacancy ordering and provides a new avenue for developing high‐energy and long‐durability sodium layered oxide cathodes. [ABSTRACT FROM AUTHOR]

Mixed‐anion compounds have attracted growing attentions, but their synthesis is challenging, making a rational search desirable. Here, we explored LaF3‐LaX3 (X=Cl, Br, I) system using ab initio structure searches based on evolutionary algorithms, and predicted LaF2X and LaFX2 (X=Br, I), which are respectively isostructural with LaHBr2 and YH2I, consisting of layered La‐F blocks with single and double ordered honeycomb lattices, separated by van der Waals gaps. We successfully synthesized these compounds: LaF2Br and LaFI2 crystallize in the predicted structure, while LaF2I is similar to the predicted one but with different layer stacking. LaF2I exhibits fluoride ion conductivity comparable to that of non‐doped LaF3, and has the potential to show better ionic conductivity upon appropriate doping, given the theoretically lower diffusion energy barrier and the presence of soft iodine anions. This study shows the structure prediction using evolutionary algorithms will accelerate the discovery of mixed‐anion compounds in future, in particular those with an ordered anion arrangement. [ABSTRACT FROM AUTHOR]

Mixed‐anion compounds have attracted growing attentions, but their synthesis is challenging, making a rational search desirable. Here, we explored LaF3‐LaX3 (X=Cl, Br, I) system using ab initio structure searches based on evolutionary algorithms, and predicted LaF2X and LaFX2 (X=Br, I), which are respectively isostructural with LaHBr2 and YH2I, consisting of layered La‐F blocks with single and double ordered honeycomb lattices, separated by van der Waals gaps. We successfully synthesized these compounds: LaF2Br and LaFI2 crystallize in the predicted structure, while LaF2I is similar to the predicted one but with different layer stacking. LaF2I exhibits fluoride ion conductivity comparable to that of non‐doped LaF3, and has the potential to show better ionic conductivity upon appropriate doping, given the theoretically lower diffusion energy barrier and the presence of soft iodine anions. This study shows the structure prediction using evolutionary algorithms will accelerate the discovery of mixed‐anion compounds in future, in particular those with an ordered anion arrangement. [ABSTRACT FROM AUTHOR]

The core task for Mott insulators includes how rigid distributions of electrons evolve and how these induce exotic physical phenomena. However, it is highly challenging to chemically dope Mott insulators to tune properties. Herein, we report how to tailor electronic structures of the honeycomb Mott insulator RuCl3 employing a facile and reversible single‐crystal to single‐crystal intercalation process. The resulting product (NH4)0.5RuCl3⋅1.5 H2O forms a new hybrid superlattice of alternating RuCl3 monolayers with NH4+ and H2O molecules. Its manipulated electronic structure markedly shrinks the Mott–Hubbard gap from 1.2 to 0.7 eV. Its electrical conductivity increases by more than 103 folds. This arises from concurrently enhanced carrier concentration and mobility in contrary to the general physics rule of their inverse proportionality. We show topotactic and topochemical intercalation chemistry to control Mott insulators, escalating the prospect of discovering exotic physical phenomena. [ABSTRACT FROM AUTHOR]

Electrocatalytic two‐electron oxygen reduction has emerged as a promising alternative to the energy‐ and waste‐intensive anthraquinone process for distributed H2O2 production. This process, however, suffers from strong competition from the four‐electron pathway leading to low H2O2 selectivity. Herein, we report using a superhydrophilic O2‐entrapping electrocatalyst to enable superb two‐electron oxygen reduction electrocatalysis. The honeycomb carbon nanofibers (HCNFs) are robust and capable of achieving a high H2O2 selectivity of 97.3 %, much higher than that of its solid carbon nanofiber counterpart. Impressively, this catalyst achieves an ultrahigh mass activity of up to 220 A g−1, surpassing all other catalysts for two‐electron oxygen reduction reaction. The superhydrophilic porous carbon skeleton with rich oxygenated functional groups facilitates efficient electron transfer and better wetting of the catalyst by the electrolyte, and the interconnected cavities allow for more effective entrapping of the gas bubbles. The catalytic mechanism is further revealed by in situ Raman analysis and density functional theory calculations. [ABSTRACT FROM AUTHOR]

This contribution describes the synthesis of colloidal di‐patch particles functionalized with DNA on the patches and their assembly into colloidal superstructures via cooperative depletion and DNA‐mediated interactions. The assembly into flower‐like Kagome, brick‐wall like monolayer, orthogonal packed single or double layers, wrinkled monolayer, and colloidal honeycomb superstructures can be controlled by tuning the particles' patch sizes and assembly conditions. Based on these experimental results, we generate an empirical phase diagram. The principles revealed by the phase diagram provide guidance in the design of two‐dimensional (2D) materials with desired superstructures. Our strategy might be translatable to the assembly of three‐dimensional (3D) colloidal structures. [ABSTRACT FROM AUTHOR]

The competition between honeycomb and hexagonal tiling of molecular units can lead to large honeycomb superstructures on surfaces. Such superstructures exhibit pores that may be used as 2D templates for functional guest molecules. Honeycomb superstructures of molecules that comprise a C3 symmetric platform on Au(111) and Ag(111) surfaces are presented. The superstructures cover nearly mesoscopic areas with unit cells containing up to 3000 molecules, more than an order of magnitude larger than previously reported. The unit cell size may be controlled by the coverage. A fairly general model was developed to describe the energetics of honeycomb superstructures built from C3 symmetric units. Based on three parameters that characterize two competing bonding arrangements, the model is consistent with the present experimental data and also reproduces various published results. The model identifies the relevant driving force, mostly related to geometric aspects, of the pattern formation. [ABSTRACT FROM AUTHOR]

Phosphorus‐rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low‐temperature phosphorization method based on Mg reducing PCl3 in ZnCl2 molten salt at 300 °C is developed to synthesize phosphorus‐rich CuP2@C from a Cu‐MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn2+ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP2 nanocrystals. The honeycomb CuP2@C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g−1 at 0.2 A g−1) and superior cycling stability (720 mAh g−1 after 600 cycles at 1.0 A g−1), showing the promising application of P‐rich metal phosphides in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Clusters with diverse structures and functions have been used to create novel cluster-assembled materials (CAMs). Understanding their self-assembly process is a prerequisite to optimize their structure and function. Herein, two kinds of unlike organo-functionalized inorganic clusters are covalently linked by a short organic tether to form a dumbbell-shaped Janus co-cluster. In a mixed solvent of acetonitrile and water, it self-assembles into a crystal with a honeycomb superstructure constructed by hexagonal close-packed cylinders of the smaller cluster and an orderly arranged framework of the larger cluster. Reconstruction of these structural features via coarse-grained molecular simulations demonstrates that the cluster crystallization and the nanoscale phase separation between the two incompatible clusters synergistically result in the unique nano-architecture. Overall, this work opens up new opportunities for generating novel CAMs for advanced future applications. [ABSTRACT FROM AUTHOR]

A useful Li: A simple reaction between Li2O and CO, gives a new type of three‐dimensional graphene sheets—honeycomb‐structured graphene. A dye‐sensitized solar cell (DSSC) with the new graphene counter electrode has an energy conversion efficiency as high as 7.8 %, which is comparable to that of DSSCs with an expensive Pt counter electrode. [ABSTRACT FROM AUTHOR]

2D boron has been proposed to follow a honeycomb grid when deposited on a metal surface. However, in their Communication on page 13022 ff., B. I. Yakobson et al. show theoretically that pure boron is the first 2D material that varies its structure depending on the metal substrate: on Cu, Au, or Ag different boron sheets should be formed making it different from 2D graphene or hexagonal boron nitride which have an exclusively honeycomb lattice when deposited on different metal substrates. [ABSTRACT FROM AUTHOR]