Holey penta-hexagonal graphene: a promising anode material for Li-ion batteries.

Carbon allotropes are widely used as anode materials in Li batteries, with graphite being commercially successful. However, the limited capacity and cycling stability of graphite impede further advancement and hinder the development of electric vehicles. Herein, through density functional theory (DFT) computations and molecular dynamics (AIMD) simulations, we proposed holey penta-hexagonal graphene (HPhG) as a potential anode material, achieved through active site designing.

Suppressed Fermi Level Pinning and Wide-Range Tunable Schottky Barrier in CrX (X = I, Br)/2D Metal Contacts.

CrX (X = I, Br) monolayers exhibit outstanding performance in spintronic devices. However, the Schottky barrier at the CrX/electrode interface severely impedes the charge injection efficiency. Herein, we propose two-dimensional (2D) metals as electrodes to form van der Waals (vdW) contact with CrX monolayers and systematically explore the contact properties of CrX/metal by density functional theory (DFT) calculations.

A polymeric hydrogel electrocatalyst for direct water oxidation.

Metal-free electrocatalysts represent a main branch of active materials for oxygen evolution reaction (OER), but they excessively rely on functionalized conjugated carbon materials, which substantially restricts the screening of potential efficient carbonaceous electrocatalysts. Herein, we demonstrate that a mesostructured polyacrylate hydrogel can afford an unexpected and exceptional OER activity - on par with that of benchmark IrO catalyst in alkaline electrolyte, together with a high durability and good adaptability in various pH environments. Combined theoretical and electrokinetic studies reveal that the positively charged carbon atoms within the carboxylate units are intrinsically active toward OER, and spectroscopic operando characterizations also identify the fingerprint superoxide intermediate generated on the polymeric hydrogel backbone.

Narrowing the band gap and suppressing electron-hole recombination in β-FeO by chlorine doping.

The effects of halogen (F, Cl, Br, I, and At) doping in the direct-band-gap β-FeO semiconductor on its band structures and electron-hole recombination have been investigated by density functional theory. Doping Br, I, and At in β-FeO leads to transformation from a direct-band-gap semiconductor to an indirect-band-gap semiconductor because their atomic radii are too large; however, F- and Cl-doped β-FeO remain as direct-band-gap semiconductors. Due to the deep impurity states of the F dopant, this study focuses on the effects of the Cl dopant on the band structures of β-FeO.

A two-dimensional BeAu monolayer with planar hexacoordinate s-block metal atoms: a superconducting global minimum Dirac material with two perfect Dirac node-loops.

Using a starlike BeAu cluster as a building block and following the bottom-up strategy, an intriguing two-dimensional (2D) binary s-block metal BeAu monolayer with a 6/ space group was theoretically designed. Both the BeAu cluster and the 2D monolayer are global minima featuring rule-breaking planar hexacoordinate motifs (anti-van't Hoff/Le Bel arrangement), and their high stabilities are attributed to good electron delocalization and electronic-stabilization-induced steric force. Strikingly, the BeAu monolayer is a rare Dirac material with two perfect Dirac node-loops in the band structure and is a phonon-mediated superconductor with a critical temperature of 4.

He's Yangchao Recipe Ameliorates Ovarian Oxidative Stress of Aging Mice under Consecutive Superovulation Involving JNK- And P53-Related Mechanism.

Objective: To evaluate the effects of He's Yangchao Recipe (HSYC) on ameliorating ovarian oxidative stress of aging mice under consecutive superovulation.

Methods: An 8-month-old C57BL/6 female mouse was chosen to establish an aging model under ovarian hyperstimulation. Mice were randomly separated into four groups: 1 as the control group, 4 as the model group, NR4 with N-acetyl-L-cysteine (NAC) administration, and TR4 with HSYC administration.

Particle Swarm Predictions of a SrB Monolayer with 12-Fold Metal Coordination.

Materials containing planar hypercoordinate motifs greatly enriched the fundamental understanding of chemical bonding. Herein, by means of first-principles calculations combined with global minimum search, we discovered the two-dimensional (2D) SrB monolayer, which has the highest planar coordination number (12) reported so far in extended periodic materials. In the SrB monolayer, bridged B units are forming the boron monolayer consisting of B rings, and the Sr atoms are embedded at the center of these B rings, leading to the Sr@B motifs.

Atomically Dispersed Uranium Enables an Unprecedentedly High NH Yield Rate.

The low NH yield rate is a grand challenge for electrocatalytic N reduction to NH. Herein, we report the first uranium single-atom catalyst (SAC) capable of catalyzing the electrochemical N reduction reaction (NRR). The uranium SAC features a low limiting potential (<0.

Understanding the CH Conversion over Metal Dimers from First Principles.

Inspired by the advantages of bi-atom catalysts and recent exciting progresses of nanozymes, by means of density functional theory (DFT) computations, we explored the potential of metal dimers embedded in phthalocyanine monolayers (M-Pc), which mimics the binuclear centers of methane monooxygenase, as catalysts for methane conversion using HO as an oxidant. In total, 26 transition metal (from group IB to VIIIB) and four main group metal (M = Al, Ga, Sn and Bi) dimers were considered, and two methane conversion routes, namely *O-assisted and *OH-assisted mechanisms were systematically studied. The results show that methane conversion proceeds via an *OH-assisted mechanism on the Ti-Pc, Zr-Pc and Ta-Pc, a combination of *O- and *OH-assisted mechanism on the surface of Sc-Pc, respectively.

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

The discovery of ferromagnetism in monolayer transition metal halides exemplified by CrI 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 CuCl 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 CuCl reaches ∼47 K, and its ferromagnetism is associated with the strong hybridization between the Cu 3d and Cl 3p states in the configuration.

Controllable CO electrocatalytic reduction via ferroelectric switching on single atom anchored InSe monolayer.

Efficient and selective CO electroreduction into chemical fuels promises to alleviate environmental pollution and energy crisis, but it relies on catalysts with controllable product selectivity and reaction path. Here, by means of first-principles calculations, we identify six ferroelectric catalysts comprising transition-metal atoms anchored on InSe monolayer, whose catalytic performance can be controlled by ferroelectric switching based on adjusted d-band center and occupation of supported metal atoms. The polarization dependent activation allows effective control of the limiting potential of CO reduction on TM@InSe (TM = Ni, Pd, Rh, Nb, and Re) as well as the reaction paths and final products on Nb@InSe and Re@InSe.

Tunable electronic properties and enhanced ferromagnetism in CrGeTemonolayer by strain engineering.

Recently, as a new representative of Heisenberg's two-dimensional (2D) ferromagnetic materials, 2D CrGeTe(CGT), has attracted much attention due to its intrinsic ferromagnetism. Unfortunately, the Curie temperature () of CGT monolayer is only 22 K, which greatly hampers the development of the applications based on the CGT materials. Herein, by means of density functional theory computations, we explored the electronic and magnetic properties of CGT monolayer under the applied strain.

CN and CNS monolayers as promising anchoring materials for lithium-sulfur batteries: weakening the shuttle effect optimizing lithium bonds.

The notorious polysulfide shuttle effect is a crucial factor responsible for the degradation of Li-S batteries. A good way to suppress the shuttle effect is to effectively anchor dissoluble lithium polysulfides (LPSs, Li2Sn) on appropriate substrates. Previous studies have revealed that Li of Li2Sn is prone to interact with the N of N-containing materials to form Li-N bonds.

Enhancing Ferromagnetism and Tuning Electronic Properties of CrI Monolayers by Adsorption of Transition-Metal Atoms.

Among first experimentally discovered two-dimensional (2D) ferromagnetic materials, chromium triiodide (CrI) monolayers have attracted particular attention due to their potential applications in electronics and spintronics. However, the Curie temperature of the CrI monolayer is below room temperature, which greatly limits practical development of the devices. Herein, using density functional theory calculation, we explore how the electronic and magnetic properties of CrI monolayers change upon adsorption of 3d transition-metal (TM) atoms (from Sc to Zn).

MX Anti-MXenes from Non-van der Waals Bulks for Electrochemical Applications: The Merit of Metallicity and Active Basal Plane.

Two-dimensional transition-metal compounds (2DTMCs) are promising materials for electrochemical applications, but 2DTMCs with metallicity and active basal planes are rare. In this work, we proposed a simple and effective strategy to extract 2DTMCs from non-van der Waals bulk materials and established a material library of 79 2DTMCs, which we named as anti-MXenes since they are composed of one M atomic layer sandwiched by two X atomic layers. By means of density functional theory computations, 24 anti-MXenes were confirmed to be thermodynamically, dynamically, mechanically, and thermally stable.

Enhanced performance of MoP monolayer as lithium-ion battery anode materials by carbon and nitrogen doping: a first principles study.

By means of density functional theory (DFT) computations, we explored the potential of carbon- and nitrogen-doped Mo2P (CMP and NMP) layered materials as the representative of transition metal phosphides (TMPs) for the development of lithium-ion battery (LIB) anode materials, paying special attention to the synergistic effects of the dopants. Both CMP and NMP have exceptional stabilities and excellent electronic conductivity, and a high theoretical maximum storage capacity of ∼ 486 mA h g-1. Li-ion diffusion barriers on the two-dimensional (2D) CMP and NMP surfaces are extremely low (∼0.

In Situ Observation of Non-Classical 2-Norbornyl Cation in Confined Zeolites at Ambient Temperature.

Carbonium ions are an important class of reaction intermediates, but their dynamic evolution is difficult to be monitored by in situ techniques under experimental conditions because of their extremely short lifetime. Probably the most famous case is 2-norbornyl cation (2NB ): its existing form (classical or non-classical) had been debated for decades, until the concrete proof of non-classical geometry was achieved by X-ray crystallographic characterization at ultra-low temperature (40 K) and super acidic environment. However, we lack the understanding about 2NB at ambient conditions.

Rational Prediction of Single Metal Atom Supported on Two-Dimensional Metal Diborides for Electrocatalytic N Reduction Reaction with Integrated Descriptor.

Nitrogen reduction reaction (NRR) plays an important role in chemical industry, so it is significant to develop low-cost and efficient electrocatalysts for nitrogen fixation instead of the traditional Haber-Bosch process. In this paper, the electrocatalytic performance of various single atoms doped on two-dimensional metal diborides with a B vacancy for N reduction to ammonia is calculated and predicted. By screening numerous catalysts, we find that Ti@VB is the most active catalyst for NRR, and the limiting potential of Ti@VB for NRR is -0.

Enhanced Ferromagnetism and Tunable Magnetism in FeGeTe Monolayer by Strain Engineering.

Recent discovery of intrinsic ferromagnetism in FeGeTe (FGT) monolayer [Deng, Y.; 2018, 563, 94-99; Fei, Z.; 2018, 17, 778-782] not only extended the family of two-dimensional (2D) magnetic materials but also stimulated further interest in the possibility to tune their magnetic properties without changing the chemical composition or introducing defects.

Metallic FeSe monolayer as an anode material for Li and non-Li ion batteries: a DFT study.

By means of density functional theory computations, we explored the electrochemical performance of an FeSe monolayer as an anode material for lithium and non-lithium ion batteries (LIBs and NLIBs). The electronic structure, adsorption, diffusion, and storage behavior of different metal atoms (M) in FeSe were systematically investigated. Our computations revealed that M adsorbed FeSe (M = Li, Na and K) systems show metallic characteristics that give rise to good electrical conductivity and mobility with low activation energies for diffusion (0.

Planar Hypercoordinate Motifs in Two-Dimensional Materials.

ConspectusAs one of the most important and versatile elements, carbon renders itself as one of the most fundamental and cutting-edge topics in chemistry, physics, and materials science. Many carbon-based chemical rules were established accordingly. While the tetrahedral predilection of tetracoordinate carbon has been a cornerstone of organic chemistry since 1874, almost a century later tetracoordinate carbon was found to be able to adopt planar structures known as planar tetracoordinate carbon (ptC), which are stabilized electronically by good π-acceptor (delocalization of a lone electron pair of ptC) or σ-donor (promoting electron transfer to electron-deficient bonding) substituents or mechanically by appropriate steric enforcement.

Polymorphism of low dimensional boron nanomaterials driven by electrostatic gating: a computational discovery.

The successful synthesis of two-dimensional (2D) boron sheets typically relies on the utilization of a silver surface, which acts as a gated substrate compensating for the electron-deficiency of boron. However, how the structures of one-dimensional (1D) boron are affected by the gating effect remains unclear. By means of an unbiased global minimum structure search and density functional theory (DFT) computations, we discovered the coexistence of 2D boron sheets and 1D ribbons triggered by electrostatic gating.

Tackling the Activity and Selectivity Challenges of Electrocatalysts toward the Nitrogen Reduction Reaction via Atomically Dispersed Biatom Catalysts.

Developing efficient catalysts for nitrogen fixation is becoming increasingly important but is still challenging due to the lack of robust design criteria for tackling the activity and selectivity problems, especially for electrochemical nitrogen reduction reaction (NRR). Herein, by means of large-scale density functional theory (DFT) computations, we reported a descriptor-based design principle to explore the large composition space of two-dimensional (2D) biatom catalysts (BACs), namely, metal dimers supported on 2D expanded phthalocyanine (M-Pc or MM'-Pc), toward the NRR at the acid conditions. We sampled both homonuclear (M-Pc) and heteronuclear (MM'-Pc) BACs and constructed the activity map of BACs by using NH* adsorption energy as the activity descriptor, which reduces the number of promising catalyst candidates from over 900 to less than 100.