Friction properties of black phosphorus: a first-principles study.

Based on the first-principle, the friction anisotropy, structural super-lubricity and oxidation induced ultra-low friction of black phosphorus at atomic scale under different loads have been studied. The results show that the interface friction of black phosphorus is anisotropic, that is, the friction along the armchair direction is greater than that along the zigzag direction. Moreover, the friction between the black phosphorus interfaces shows a structural superlubricity property, and the incommensurate interface friction is approximately one thousandth of the commensurate interface friction, which is mainly due to the less electronic charge and the smaller amplitude of electronic charge change between the incommensurate interfaces during the friction process. In addition, the oxidation of black phosphorus is beneficial for lubrication between interfaces.

Pressure enhanced negative thermal expansion in 2H CuScO2 from first-principles calculations.

Finding materials with negative thermal expansion (NTE) property is challenging. Tuning NTE is of fundamental and technological importance. Pressure enhanced negative thermal expansion behavior in 2H CuScO2 is found and expounded using density functional theory (DFT) and quasi-harmonious approximation (QHA). The frequencies of low energy modes and Grüneisen parameters decrease under pressure, but the bulk modulus increases with pressure. The transverse vibration of Cu atoms becomes stronger under pressure and the materials undergo thermal softening. These factors including thermal softening, pressure induced decrease of Grüneisen parameters and pressure induced strengthening of transverse vibration of Cu atoms all contribute to the enhanced negative thermal expansion property in 2H CuScO2 in view of the thermodynamic relationship , Grüneisen's theory of thermal expansion and the mechanism of NTE, respectively.

Enhanced Electrochemical Water Oxidation Activity by Structural Engineered Prussian Blue Analogue/rGO Heterostructure.

Prussian blue analogue (PBA), with a three-dimensional open skeleton and abundant unsaturated surface coordination atoms, attracts extensive research interest in electrochemical energy-related fields due to facile preparation, low cost, and adjustable components. However, it remains a challenge to directly employ PBA as an electrocatalyst for water splitting owing to their poor charge transport ability and electrochemical stability. Herein, the PBA/rGO heterostructure is constructed based on structural engineering. Graphene not only improves the charge transfer efficiency of the compound material but also provides confined growth sites for PBA. Furthermore, the charge transfer interaction between the heterostructure interfaces facilitates the electrocatalytic oxygen evolution reaction of the composite, which is confirmed by the results of the electrochemical measurements. The overpotential of the PBA/rGO material is only 331.5 mV at a current density of 30 mA cm-2 in 1.0 M KOH electrolyte with a small Tafel slope of 57.9 mV dec-1, and the compound material exhibits high durability lasting for 40 h.

Na doping into Li-rich layered single crystal nanoparticles for high-performance lithium-ion batteries cathodes.

Lithium-rich layered manganese-based cathodes (LRLMOs) with first-class energy density (∼1000 W h kg-1) have attracted wide attention. Nevertheless, the weak cycle stability and bad rate capability obstruct their large-scale commercial application. Here, single crystal Li1.2-xNaxNi0.2Mn0.6O2(x = 0, 0.05, 0.1, 0.15) nanoparticles are designed and successfully synthesized due to the single crystal structure with smaller internal stress and larger ionic radius of Na. The synergistic advantages of single crystal structure and Na doping are authenticated as cathodes for Li ion batteries (LIBs), which can consolidate the crystallographic structure and be benefit for migration of lithium ion. Among all the Na doping single crystals, Li1.1Na0.1Ni0.2Mn0.6O2cathode possesses supreme cycling life and discharge capacity at large current density. To be more specific, it exhibits a discharge capacity of 264.2 mAh g-1after 50 charge and discharge cycles, higher than that of undoped material (214.9 mAh g-1). The discharge capacity of Li1.1Na0.1Ni0.2Mn0.6O2cathode at 10 C (1 C = 200 mA g-1) is enhanced to 160.4 mAh g-1(106.7 mAh g-1forx = 0 sample). The creative strategy of Na doping single crystal LRLMOs might furnish an idea to create cathode materials with high energy and power density for next generation LIBs.

Phosphorus Enhanced Intermolecular Interactions of SnO2 and Graphene as an Ultrastable Lithium Battery Anode.

SnO2 suffers from fast capacity fading in lithium-ion batteries due to large volume expansion as well as unstable solid electrolyte interphase. Herein, the design and synthesis of phosphorus bridging SnO2 and graphene through covalent bonding are demonstrated to achieve a robust structure. In this unique structure, the phosphorus is able to covalently "bridge" graphene and tin oxide nanocrystal through PC and SnOP bonding, respectively, and act as a buffer layer to keep the structure stable during charging-discharging. As a result, when applied as a lithium battery anode, SnO2 @P@GO shows very stable performance and retains 95% of 2nd capacity onward after 700 cycles. Such unique structural design opens up new avenues for the rational design of other high-capacity materials for lithium battery, and as a proof-of-concept, creates new opportunities in the synthesis of advanced functional materials for high-performance energy storage devices.

Dietary Supplementation of Tannic Acid Promotes Performance of Beef Cattle via Alleviating Liver Lipid Peroxidation and Improving Glucose Metabolism and Rumen Fermentation.

This study aimed to investigate the effects of dietary tannic acid (TAN) on the gas production, growth performance, antioxidant capacity, rumen microflora, and fermentation function of beef cattle through in vitro and in vivo experiments. TAN was evaluated at 0.15% (dry matter basis, DM) in the in vitro experiment and 0.20% (DM basis) in the animal feeding experiment. The in vitro results revealed that compared with control (CON, basal diet without TAN), the addition of TAN significantly increased the cumulative gas production and asymptotic gas production per 0.20 g dry matter substrate (p < 0.01), with a tendency to reduce methane concentration after 96 h of fermentation (p = 0.10). Furthermore, TAN supplementation significantly suppressed the relative abundance of Methanosphaera and Methanobacteriaceae in the fermentation fluid (LDA > 2.50, p < 0.05). The in vivo experiment showed that compared with CON, the dietary TAN significantly improved average daily gain (+0.15 kg/d), dressing percent (+1.30%), net meat percentage (+1.60%), and serum glucose concentration (+23.35%) of beef cattle (p < 0.05), while it also significantly reduced hepatic malondialdehyde contents by 25.69% (p = 0.02). Moreover, the TAN group showed significantly higher alpha diversity (p < 0.05) and increased relative abundance of Ruminococcus and Saccharomonas (LDA > 2.50, p < 0.05), while the relative abundance of Prevotellaceae in rumen microbial community was significantly decreased (p < 0.05) as compared to that of the CON group. In conclusion, the dietary supplementation of TAN could improve the growth and slaughter performance and health status of beef cattle, and these favorable effects might be attributed to its ability to alleviate liver lipid peroxidation, enhance glucose metabolism, and promote a balanced rumen microbiota for optimal fermentation.

A versatile method for controlled synthesis of porous hollow spheres.

A versatile method was developed to synthesize nickel silicate, silica, and silica-nickel composite porous hollow spheres by using silica spheres as templates. In the preparation, silica spheres were treated with a mixture of NiSO(4)·6H(2)O and NH(3)·H(2)O. The nickel-based ingredient reacted with the silica to form a shell while the alkaline solution could remove the silica core, thus forming the nickel silicate hollow spheres. After these spheres were further treated with hydrogen in reduction or with HCl in etching, they became silica-nickel hollow spheres or silica hollow spheres, respectively. The sizes of these hollow spheres depended on the concentration of the precursor. Our investigation also found that their surface properties or magnetic properties could be tailored by adjusting the fabrication parameters.

Silica colloidal spheres as metal ions reservoir for synthesis of semiconductor core-shell structure and hollow spheres.

Serial semiconductors core-shell and hollow sphere structures were prepared by using silica colloidal spheres as template in alkaline solution. This method presented in this paper involves mainly two steps with metal ions stored into surface layer of silica colloidal spheres in alkaline condition in the first step, followed metal ions reacted with thioacetamide to form semiconductor shell under microwave heating in a short-time. Cadmium ions were used as an example to illustrate the synthesis process. The electron microscopy results suggested that CdS core-shell structure and hollow spheres with complete and uniform shell were successfully synthesized, and the thickness of shell can be controlled in a certain range precisely. The mechanism of this method was discussed in detail. In addition, complex peanut hollow structure was synthesized by using this method, which indicated that this method might be extended to synthesize desired morphology with corresponding silica template. This novel method provides an avenue to synthesize uniform different semiconductor core-shell structure and hollow spheres with controllable morphology and shell thickness.

Variation of 423G>T in the Agouti gene exon 4 in indigenous chinese goat breeds.

The Agouti gene plays an important role in pigment synthesis in domestic animals. A transversion of 423G>T recognized by BanII was found after a fragment (178 bp) of the goat Agouti gene exon 4 was amplified and sequenced. To investigate its genetic effect and diversity, 677 individuals from 12 indigenous Chinese goat breeds and one imported goat breed from South Africa (Boer goat) were analyzed by PCR-RFLP. Two alleles, T and G, and three genotypes, TT, TG, and GG, were detected. Allele T had a higher frequency in most goat breeds and, combined with the coat color phenotype, is believed to be responsible for the black phenotype or to be linked with the causative site in the goat. The results also indicate that the 423G>T transversion showed lower genetic diversity in goat breeds with black coat color in China. Genetic differentiation among the 13 goat populations was 0.2023. The clustering of populations based on the 423G>T site was basically consistent with the variation of coat color.

ZnSe Microsphere/Multiwalled Carbon Nanotube Composites as High-Rate and Long-Life Anodes for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are considered as one of the most favorable alternative devices for sustainable development of modern society. However, it is still a big challenge to search for proper anode materials which have excellent cycling and rate performance. Here, zinc selenide microsphere and multiwalled carbon nanotube (ZnSe/MWCNT) composites are prepared via hydrothermal reaction and following grinding process. The performance of ZnSe/MWCNT composites as a SIB anode is studied for the first time. As a result, ZnSe/MWCNTs exhibit excellent rate capacity and superior cycling life. The capacity retains as high as 382 mA h g-1 after 180 cycles even at a current density of 0.5 A g-1. The initial Coulombic efficiency of ZnSe/MWCNTs can reach 88% and nearby 100% in the following cycles. The superior electrochemical properties are attributed to continuous electron transport pathway, improved electrical conductivity, and excellent stress relaxation.

Rapid, all dry microfabrication of three-dimensional Co3O4/Pt nanonetworks for high-performance microsupercapacitors.

On-chip electrochemical energy storage devices have attracted growing attention due to the decreasing size of electronic devices. Various approaches have been applied for constructing the microsupercapacitors. However, the microfabrication of high-performance microsupercapacitors by conventional and fully compatible semiconductor microfabrication technologies is still a critical challenge. Herein, unique three-dimensional (3D) Co3O4 nanonetwork microelectrodes formed by the interconnection of Co3O4 nanosheets are constructed by controllable physical vapor deposition combined with rapid thermal annealing. This construction process is an all dry and rapid (≤5 minutes) procedure. Afterward, by sputtering highly electrically conductive Pt nanoparticles on the microelectrodes, the 3D Co3O4/Pt nanonetworks based microsupercapacitor is fabricated, showing a high volume capacitance (35.7 F cm-3) at a scan rate of 20 mV s-1 due to the unique interconnected structures, high electrical conductivity and high surface area of the microelectrodes. This microfabrication process is also used to construct high-performance flexible microsupercapacitors, and it can be applied in the construction of wearable devices. The proposed strategy is completely compatible with the current semiconductor microfabrication and shows great potential in the applications of the large-scale integration of micro/nano and wearable devices.

Porous and Low-Crystalline Manganese Silicate Hollow Spheres Wired by Graphene Oxide for High-Performance Lithium and Sodium Storage.

Herein, a graphene oxide (GO)-wired manganese silicate (MS) hollow sphere (MS/GO) composite is successfully synthesized. Such an architecture possesses multiple advantages in lithium and sodium storage. The hollow MS structure provides a sufficient free space for volume variation accommodation; the porous and low-crystalline features facilitate the diffusion of lithium ions; meanwhile, the flexible GO sheets enhance the electronic conductivity of the composite to a certain degree. When applied as the anode material for lithium-ion batteries (LIBs), the as-obtained MS/GO composite exhibits a high reversible capacity, ultrastable cyclability, and good rate performance. Particularly, the MS/GO composite delivers a high capacity of 699 mA h g-1 even after 1000 cycles at 1 A g-1. The sodium-storage performance of MS/GO has been studied for the first time, and it delivers a stable capacity of 268 mA h g-1 after 300 cycles at 0.2 A g-1. This study suggests that the rational design of metal silicates would render them promising anode materials for LIBs and SIBs.

Ultralong Sb2Se3 Nanowire-Based Free-Standing Membrane Anode for Lithium/Sodium Ion Batteries.

Metal chalcogenides have emerged as promising anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, a free-standing membrane based on ultralong Sb2Se3 nanowires has been successfully fabricated via a facile hydrothermal synthesis combined with a subsequent vacuum filtration treatment. The as-achieved free-standing membrane constructed by pure Sb2Se3 nanowires exhibits good flexibility and integrity. Meanwhile, we investigate the lithium and sodium storage behavior of the Sb2Se3 nanowire-based free-standing membrane. When applied as the anode for LIBs, it delivers a reversible capacity of 614 mA h g-1 at 100 mA g-1, maintaining 584 mA h g-1 after 50 cycles. When applied as the anode for SIBs, it delivers a reversible capacity of 360 mA h g-1 at 100 mA g-1, retaining 289 mA h g-1 after 50 cycles. Such difference in electrochemical performance can be attributed to the more complex sodiation process relative to the corresponding lithiation process. This work may provide insight on developing Sb2Se3-based anode materials for high-performance LIBs or SIBs.

Copper Silicate Hydrate Hollow Spheres Constructed by Nanotubes Encapsulated in Reduced Graphene Oxide as Long-Life Lithium-Ion Battery Anode.

Hierarchical copper silicate hydrate hollow spheres-reduced graphene oxide (RGO) composite is successfully fabricated by a facile hydrothermal method using silica as in situ sacrificing template. The electrochemical performance of the composite as lithium-ion battery anode was studied for the first time. Benefiting from the synergistic effect of the hierarchical hollow structure and conductive RGO matrix, the composite exhibits excellent long-life performance and rate capability. A capacity of 890 mAh/g is achieved after 200 cycles at 200 mA/g and a capacity of 429 mAh/g is retained after 800 cycles at 1000 mA/g. The results indicate that the strategy of combining hierarchical hollow structures with conductive RGO holds the potential in addressing the volume expansion issue of high capacity anode materials.