Observation of non-superconducting phase changes in nitrogen doped lutetium hydrides.

The recent report of near-ambient superconductivity and associated color changes in pressurized nitrogen doped lutetium hydride has triggered worldwide interest and raised major questions about the nature and underlying physics of these latest claims. Here we report synthesis and characterization of high-purity nitrogen doped lutetium hydride LuHN. We find that pressure conditions have notable effects on Lu-N and Lu-NH chemical bonding and the color changes likely stem from pressure-induced electron redistribution of nitrogen/vacancies and interaction with the LuH framework.

Enhanced Thermoelectric Performance in Black Phosphorene via Tunable Interlayer Twist.

Twist-angle two-dimensional (2D) systems are attractive in their exotic and tunable properties by the formation of the moiré superlattices, allowing easy access to manipulating intrinsic electrical and thermal properties. Here, the angle-dependent thermoelectric properties of twisted bilayer black phosphorene (tbBP) by first-principles calculations are reported. The simulations show that significantly enhanced Seebeck coefficient and power factor can be achieved in p-type tbBP due to merging of the multi-valley electronic states and flat moiré bands.

Superior Conversion Efficiency Achieved in GeP/h-BN Heterostructures as Novel Flexible and Ultralight Thermoelectrics.

GeP materials are attracting broad research interest due to their typical puckered layer structure, high carrier mobility, and chemical stability. This peculiarity expedites the independent control of anisotropic electrical and thermal conductance, which is thus expected to possess great thermoelectric potential. Nevertheless, the metal characteristics of GeP in the bulk and thick films are adverse to real application because of the low Seebeck coefficient.

Crystalline Structures and Energetic Properties of Lithium Pentazolate under Ambient Conditions.

Recently, it has been reported that high-pressure synthesized lithium pentazolates could be quenched down to ambient conditions. However, the crystalline structures of LiN under ambient conditions are still ambiguous. In this work, the structures of LiN compound were directly explored at atmospheric pressure by using a new constrain structure search method.

Stabilization of the High-Energy-Density CuN Salts under Ambient Conditions by a Ligand Effect.

A series of excellent works have demonstrated that high-nitrogen-content metal pentazolate (N ) compounds could be stabilized by high pressure. However, under ambient conditions, low stability precludes their synthesis and application in the field of high-energy-density material. In this work, by using a constrained structure search method, we predicted two new structures as 222-CuN and 2/-CuN containing N with strong N-N and Cu-N bonds.

Enhanced strength of nano-polycrystalline diamond by introducing boron carbide interlayers at the grain boundaries.

Polycrystalline diamond with high mechanical properties and excellent thermal stability plays an important role in industry and materials science. However, the increased inherent brittle strength with the increase of hardness has severely limited its further widespread application. In this work, we produced well-sintered nano-polycrystalline (np) diamond by directly sintering fine diamond powders with the boron carbide (BC) additive at high pressure and high temperatures.

Heat treatment to improve the wear resistance of PTFE/PMMA composites.

Polytetrafluoroethylene/poly(methyl methacrylate) (PTFE/PMMA) composites were prepared by a self-curing method. The influence of heat treatment processes on the friction and wear behaviors of PTFE/PMMA composites against bearing steel balls were studied by a ball-on-disk tribometer. The thermal performance of PTFE/PMMA composites with heat treatment was analyzed by Thermogravimetric Analysis (TGA).

Liquid-exfoliation of S-doped black phosphorus nanosheets for enhanced oxygen evolution catalysis.

Black phosphorus (BP) has recently drawn great attention in the field of electrocatalysis due to its distinct electrocatalytic activity for the oxygen evolution reaction (OER). However, the slow OER kinetics and the poor environmental stability of BP seriously limits its overall OER performance and prevents its electrocatalysis application. Here, sulfur (S)-doped BP nanosheets, which are prepared using high-pressure synthesis followed by liquid exfoliation, have been demonstrated to have much better OER electrocatalytic activity and environmental stability compared to their undoped counterparts.

Sulfur-Doped Black Phosphorus Field-Effect Transistors with Enhanced Stability.

Black phosphorus (BP) has drawn great attention owing to its tunable band gap depending on thickness, high mobility, and large I/ I ratio, which makes BP attractive for using in future two-dimensional electronic and optoelectronic devices. However, its instability under ambient conditions poses challenge to the research and limits its practical applications. In this work, we present a feasible approach to suppress the degradation of BP by sulfur (S) doping.

Weak antilocalization effect in exfoliated black phosphorus revealed by temperature- and angle-dependent magnetoconductivity.

Recently, there have increasingly been debates on whether there exists a surface resonance state (SRS) in black phosphorus (BP), as suggested by recent angle-resolved photoemission spectroscopy results. To resolve this issue, we have performed temperature- and angle-dependent magnetoconductivity measurements on exfoliated, high-quality BP single crystals. A pronounced weak-antilocalization (WAL) effect was observed within a narrow temperature range of 8-16 K, with the electrical current flowing parallel to the cleaved ac-plane (along the a- or c-axis) and the magnetic field along the b-axis.

Flexible Black-Phosphorus Nanoflake/Carbon Nanotube Composite Paper for High-Performance All-Solid-State Supercapacitors.

We proposed a simple route for fabrication of the flexible BP nanoflake/carbon nanotube (CNT) composite paper as flexible electrodes in all-solid-state supercapacitors. The highly conductive CNTs not only play a role as active materials but also increase conductivity of the hybrid electrode, enhance electrolyte shuttling and prevent the restacking between BP nanoflakes. The fabricated flexible all-solid-state supercapacitor (ASSP) device at the mass proportion of BP/CNTs 1:4 was found to deliver the highest volumetric capacitance of up to 41.

Te-Doped Black Phosphorus Field-Effect Transistors.

Element doping allows manipulation of the electronic properties of 2D materials. Enhanced transport performances and ambient stability of black-phosphorus devices by Te doping are presented. This provides a facile route for achieving airstable black-phosphorus devices.

Large and Anisotropic Linear Magnetoresistance in Single Crystals of Black Phosphorus Arising From Mobility Fluctuations.

Black Phosphorus (BP) is presently attracting immense research interest on the global level due to its high mobility and suitable band gap for potential application in optoelectronics and flexible devices. It was theoretically predicted that BP has a large direction-dependent electrical and magnetotransport anisotropy. Investigations on magnetotransport of BP may therefore provide a new platform for studying the nature of electron transport in layered materials.

Flexible All-Solid-State Supercapacitors based on Liquid-Exfoliated Black-Phosphorus Nanoflakes.

Flexible all-solid-state supercapacitors are fabricated with liquid-exfoliated black-phosphorus (BP) nanoflakes as an electrode material. These devices deliver high specific volumetric capacitance, power density, and energy density, up to 13.75 F cm(-3) , 8.

Enhanced stability of black phosphorus field-effect transistors with SiO₂ passivation.

Few-layer black phosphorus (BP) has attracted much attention due to its high mobility and suitable band gap for potential applic5ations in optoelectronics and flexible devices. However, its instability under ambient conditions limits its practical applications. Our investigations indicate that by passivation of the mechanically exfoliated BP flakes with a SiO2 layer, the fabricated BP field-effect transistors (FETs) exhibit greatly enhanced environmental stability.

Three-dimensional sp(2)-hybridized carbons consisting of orthogonal nanoribbons of graphene and net C.

We identify two sp(2) hybridized network models of carbon, namely GT-8 and CT-12, based on first-principles calculation results. Parallel nanoribbon rows of graphene and net C are found to be interlinked with orthogonal nanoribbons to construct GT-8 and CT-12, and their series of isomorphic analogs (named GTs and CTs) are assembled with the widening of the nanoribbon components. GTs and CTs are dynamically and mechanically stable and energetically more favorable than many previous sp(2) carbons, including K4, C20, and H6 carbon.

Removal of fluoride from aqueous solution using Zr(IV) immobilized cross-linked chitosan.

In the present paper, zirconium immobilized cross-linked chitosan (Zr-CCS) was reported for the adsorption of fluoride. Zr-CCS was synthesized by methods of membrane-forming and subsequent cross-linking reaction. Zr-CCS was characterized by FTIR, XRD, and SEM technologies.

A metallic superhard boron carbide: first-principles calculations.

A monoclinic BC3 phase (denoted M-BC3) has been predicted using first principles calculations. The M-BC3 structure is formed by alternately stacking sequences of metallic BC-layers and insulating C atom layers, thus, the structure exhibits two-dimensional conductivity. Its stability has been confirmed by our calculations of the total energy, elastic constants, and phonon frequencies.

Utilization of cross-linked chitosan/bentonite composite in the removal of methyl orange from aqueous solution.

A kind of biocomposite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction of chitosan with glutaraldehyde, which was referred to as cross-linked chitosan/bentonite (CCS/BT) composite. Adsorptive removal of methyl orange (MO) from aqueous solutions was investigated by batch method. The adsorption of MO onto CCS/BT composite was affected by the ratio of chitosan to BT and contact time.

Adsorption of an anionic azo dye by cross-linked chitosan/bentonite composite.

In this study, cross-linked chitosan (CCS)/bentonite (BT) composite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction between chitosan and glutaraldehyde. CCS/BT composite was characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal gravimetric analyses (TGA). Their adsorption characteristics were assessed by using an azo dye (Amido Black 10B) as a model adsorbate.

Adsorption of fluoride from aqueous solution by enhanced chitosan/bentonite composite.

In this work, enhanced chitosan/bentonite composite was prepared by treating chitosan/bentonite composite with concentrated hydrochloric acid (HCl). The adsorption of fluoride ions from aqueous solution onto the enhanced chitosan/bentonite composite was investigated. Adsorption studies were performed in a batch system, and the effects of various parameters, such as the pH value of the solution, adsorbent dosage and initial fluoride concentration, were evaluated.

Preparation and characterization of CTAB-HACC bentonite and its ability to adsorb phenol from aqueous solution.

A novel type of adsorbent was prepared by modifying bentonite with N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) with cetyl trimethylammonium bromide (CTAB). The adsorbent was named CTAB-HACC bentonite. Its characteristics were investigated using thermogravimetric, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction.