Tetrahedral Bonding Structure (Ni3 -Se) Induced by Lattice-Distortion of Ni to Achieve High Catalytic Activity in Na-Se Battery.

Fabrication of transition-metal catalytic materials is regarded as a promising strategy for developing high-performance sodium-selenium (Na-Se) batteries. However, more systematic explorations are further demanded to find out how their bonding interactions and electronic structures can affect the Na storage process. This study finds that lattice-distorted nickel (Ni) structure can form different bonding structures with Na2 Se4 , providing high activity to catalyze the electrochemical reactions in Na-Se batteries. Using this Ni structure to prepare electrode (Se@NiSe2 /Ni/CTs) can realize rapid charge transfer and high cycle stability of the battery. The electrode exhibits high storage performance of Na+ ; i.e., 345 mAh g⁻1 at 1 C after 400 cycles, and 286.4 mAh g⁻1 at 10 C in rate performance test. Further results reveal the existence of a regulated electronic structure with upshifts of the d-band center in the distorted Ni structure. This regulation changes the interaction between Ni and Na2 Se4 to form a Ni3 -Se tetrahedral bonding structure. This bonding structure can provide higher adsorption energy of Ni to Na2 Se4 to facilitate the redox reaction of Na2 Se4 during the electrochemical process. This study can inspire the design of bonding structure with high performance in conversion-reaction-based batteries.

Recent Advanced Development of Artificial Interphase Engineering for Stable Sodium Metal Anodes.

A solid electrolyte interphase (SEI) on a sodium (Na) metal anode strongly affects the Na deposition morphology and the cycle life of Na metal batteries (SMBs). SMB applications are hindered by an unstable SEI and dendrite growth on the Na anode surface, which directly cause low coulombic efficiency and can even lead to safety issues. An artificial interface layer can stabilize Na metal anodes, be easily tailored, and is barely affected by electrochemical processes. In this review, recent advances that support the stability of working Na metal anodes are focused via artificial interphase engineering of inorganic materials, organic materials, and organic-inorganic composite materials, with an emphasis on the significance of interface engineering in SMBs. Fundamental investigations of artificial interphase engineering are also discussed on Na metal anodes and some recent research is summarized to enhance the interface between Na metal and electrolytes using an artificial interface layer. The prospects for interphase chemistry for Na metal anodes are provided to open a way to safe, high-energy, next-generation SMBs.

Nanostructured transition-metal phthalocyanine complexes for catalytic oxygen reduction reaction.

Oxygen reduction reaction (ORR) plays a key role in the field of fuel cells. Efficient electrocatalysts for the ORR are important for fuel cells commercialization. Pt and its alloys are main active materials for ORR. However, their high cost and susceptibility to time-dependent drift hinders their applicability. Satisfactory catalytic activity of nanostructured transition metal phthalocyanine complexes (MPc) in ORR through the occurrence of molecular catalysis on the surface of MPc indicates their potential as a replacement material for precious-metal catalysts. Problems of MPc are analyzed on the basis of chemical structure and microstructure characteristics used in oxygen reduction catalysis, and the strategy for controlling the structure of MPc is proposed to improve the catalytic performance of ORR in this review.

Defects enriched cobalt molybdate induced by carbon dots for a high rate Li-ion battery anode.

A defects-enriched CoMoO4/carbon dot (CD) with CoMoO4around 37 nm is achieved via hydrothermal reaction by introducing CDs to buffer large volume changes of CoMoO4during lithiation-delithiation and enhance rate performance. The phase, morphology, microstructure, as well as the interface of the CoMoO4/CD composites were investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. When employed as Li-ion battery anode, the CoMoO4/CD exhibits a reversible capacity of ∼531 mAh g-1after 400 cycles at a current density of 2.0 A g-1. Under the scan rate at 2 mV s-1, the CoMoO4/CD shows accounts for 81.1% pseudocapacitance. It may attribute to the CoMoO4with surface defects given more reaction sites to facilitate electrons and lithium ions transfer at high current densities. Through galvanostatic intermittent titration technique, the average lithium ion diffusion coefficient calculated is an order of magnitude larger than that of bulk CoMoO4, indicating that the CoMoO4/CD possesses promising electrons and lithium ions transportation performance as anode material.

1T MoS2growth from exfoliated MoS2nucleation as high rate anode for sodium storage.

Recently, metallic 1T MoS2has been investigated due to its excellent performance in electrocatalysts, photocatalysts, supercapacitors and secondary batteries. However, there are only a few fabrication methods to synthesize stable 1T MoS2. In this work, exfoliated MoS2is employed as seed crystals for the nucleation and growth of a stable 1T MoS2grains by an epitaxial growth strategy. The 1T MoS2displays a large interlayer spacing around 0.95 nm, excellent hydrophilia and more electrochemically active sites along the basal plane, which contribute an efficient ion/electron transport pathway and structural stability. When employed as the anode material for sodium ion batteries, the 1T MoS2electrodes can survive 500 full charge/discharge cycles with a minimum capacity loss of 0.40 mAh g-1cycle-1tested at a current density of 1.0 A g-1, and the capacity degradation is as low as 0.39 mAh g-1cycle-1at a current density of 2.0 A g-1.

Walnut-like MoO2 with interconnected skeleton and opened muti-channel for fast sodium storage.

Molybdenum dioxide (MoO2) has attracted lots of theoretical interest as an anode material for sodium ion batteries (SIBs) due to its high theoretical capacity (836 mA h g-1) and metallic electrical conductivity (1.9 × 102 S cm-1). The insertion reaction, forming Na0.98MoO2 and the reversible conversion reaction, forming Mo and Na2O from Na0.98MoO2 contribute capacities of 209 and 627 mA h g-1, respectively, the latter occupies 75% of the totally theoretical capacity. However, intrinsic slow kinetics in bulk MoO2 severely restricts the redox conversion reaction. In the present work, a walnut-like MoO2 architecture (W-MoO2) with opened multi-channel and interconnected skeleton was prepared in a tube furnace, providing an interconnected ion/electron dual-pathway, which effectively facilitates Na+ diffusion and reduces the internal resistance of the cells. The W-MoO2 anode demonstrates an enhanced reversible sodium storage capacity of 354.7 mA h g-1 at 0.5 A g-1.

O3-Type Layered Ni-Rich Oxide: A High-Capacity and Superior-Rate Cathode for Sodium-Ion Batteries.

Inspired by its high-active and open layered framework for fast Li+ extraction/insertion reactions, layered Ni-rich oxide is proposed as an outstanding Na-intercalated cathode for high-performance sodium-ion batteries. An O3-type Na0.75 Ni0.82 Co0.12 Mn0.06 O2 is achieved through a facile electrochemical ion-exchange strategy in which Li+ ions are first extracted from the LiNi0.82 Co0.12 Mn0.06 O2 cathode and Na+ ions are then inserted into a layered oxide framework. Furthermore, the reaction mechanism of layered Ni-rich oxide during Na+ extraction/insertion is investigated in detail by combining ex situ X-ray diffraction, X-ray photoelectron spectroscopy, and electron energy loss spectroscopy. As an excellent cathode for Na-ion batteries, O3-type Na0.75 Ni0.82 Co0.12 Mn0.06 O2 delivers a high reversible capacity of 171 mAh g-1 and a remarkably stable discharge voltage of 2.8 V during long-term cycling. In addition, the fast Na+ transport in the cathode enables high rate capability with 89 mAh g-1 at 9 C. The as-prepared Ni-rich oxide cathode is expected to significantly break through the limited performance of current sodium-ion batteries.

Bundled Defect-Rich MoS2 for a High-Rate and Long-Life Sodium-Ion Battery: Achieving 3D Diffusion of Sodium Ion by Vacancies to Improve Kinetics.

Molybdenum disulfide (MoS2 ), a 2D-layered compound, is regarded as a promising anode for sodium-ion batteries (SIBs) due to its attractive theoretical capacity and low cost. The main challenges associated with MoS2 are the low rate capability suffering from the sluggish kinetics of Na+ intercalation and the poor cycling stability owning to the stack of MoS2 sheets. In this work, a unique architecture of bundled defect-rich MoS2 (BD-MoS2 ) that consists of MoS2 with large vacancies bundled by ultrathin MoO3 is achieved via a facile quenching process. When employed as anode for a SIB, the BD-MoS2 electrode exhibits an ultrafast charge/discharge due to the pseudocapacitive-controlled Na+ storage mechanism in it. Further experimental and theoretical calculations show that Na+ is able to cross the MoS2 layer by vacancies, not only limited to diffusion along the layer, thus realizing a 3D Na+ diffusion with faster kinetics. Meanwhile, the bundling architecture reduces the stack of sheets with a superior cycle life illustrating the highly reversible capacities of 350 and 272 mAh g-1 at 2 and 5 A g-1 after 1000 cycles.

Edges of graphene and carbon nanotubes with high catalytic performance for the oxygen reduction reaction.

We invented a practical and simple wet-grinding method to break conventional graphene sheets and CNTs for the production of new graphene/CNTs with adequate edge density (about 25 000 atoms per graphene-fragment of about 1 µm2 in size) and no detectable changes in intrinsic defects, extrinsic impurities, and even surface-area. Measurements using the standard cyclic voltammetry, rotating disk electrode and rotating ring-disk electrode techniques all confirm that such mildly fragmented graphene, as well as carbon-nanotubes treated similarly using this wet-grinding method, can facilitate the fast 4-electron oxygen reduction reaction (ORR) pathway. Our first-principles computational studies of the ORR on graphene, as well as the relevant known data in the literature, support an intriguing proposition that the ORR can be speeded up simply by increasing the edge-density of graphene. The adsorption of O2 involving both oxygen atoms, which causes O-O elongation, is best facilitated at the edge of graphene, facilitating a multi-step 4-electron ORR process.

Hybrid device employing three-dimensional arrays of MnO in carbon nanosheets bridges battery-supercapacitor divide.

It is a challenge to meld the energy of secondary batteries with the power of supercapacitors. Herein, we created electrodes finely tuned for this purpose, consisting of a monolayer of MnO nanocrystallites mechanically anchored by pore-surface terminations of 3D arrays of graphene-like carbon nanosheets ("3D-MnO/CNS"). The biomass-derived carbon nanosheets should offer a synthesis cost advantage over comparably performing designer nanocarbons, such as graphene or carbon nanotubes. High Li storage capacity is achieved by bulk conversion and intercalation reactions, while high rates are maintained through stable ∼20 nm scale diffusion distances. For example, 1332 mAh g(-1) is reached at 0.1 A g(-1), 567 mAh g(-1) at 5 A g(-1), and 285 mAh g(-1) at 20 A g(-1) with negligible degradation at 500 cycles. We employed 3D-MnO/CNS (anode) and carbon nanosheets (cathode) to create a hybrid capacitor displaying among the most promising performances reported: based on the active materials, it delivers 184 Wh kg(-1) at 83 W kg(-1) and 90 Wh kg(-1) at 15 000 W kg(-1) with 76% capacity retention after 5000 cycles.

Co-expressed network analysis based on 289 transcriptome samples reveals methyl jasmonate-mediated gene regulatory mechanism of flavonoid compounds in Dendrobium catenatum.

Flavonoids are momentous bioactive ingredients in orchid plant Dendrobium catenatum (D. catenatum), which are bioactive compounds with great medical and commercial potential. However, the accurate dissection of flavonoids profiling and their accumulation mechanism are largely unknown. In this study, methyl jasmonate (MeJA) treatment was used to investigate the change of flavonoids content and transcripts in two D. catenatum clones (A6 and B1). We identified 40 flavonoids using liquid chromatograph mass spectrometer (LC-MS). By weighted gene co-expressed network analysis (WGCNA) of flavonoids content and transcript expression of MeJA-treated samples, 37 hub genes were identified. Among them, DcCHIL, DcFLS, and DcDFR were highly correlation with two key transcription factors DcWRKY3/4 by correlation analysis of large-scale transcriptome data and above hub genes expression. Furthermore, transient overexpression of DcWRKY3/4 in tobacco leaves significantly increased the content of flavonoids. This study identified flavonoid profiling and built a new approach to mine regulatory mechanism of flavonoids in D. catenatum. These valuable flavonoids and gene resources will be key for understanding and harnessing natural flavonoids products in pharmaceuticals and foods industry of D. catenatum.

Deciphering the complex relationship between type 2 diabetes and fracture risk with both genetic and observational evidence.

The 'diabetic bone paradox' suggested that type 2 diabetes (T2D) patients would have higher areal bone mineral density (BMD) but higher fracture risk than individuals without T2D. In this study, we found that the genetically predicted T2D was associated with higher BMD and lower risk of fracture in both weighted genetic risk score (wGRS) and two-sample Mendelian randomization (MR) analyses. We also identified ten genomic loci shared between T2D and fracture, with the top signal at SNP rs4580892 in the intron of gene RSPO3. And the higher expression in adipose subcutaneous and higher protein level in plasma of RSPO3 were associated with increased risk of T2D, but decreased risk of fracture. In the prospective study, T2D was observed to be associated with higher risk of fracture, but BMI mediated 30.2% of the protective effect. However, when stratified by the T2D-related risk factors for fracture, we observed that the effect of T2D on the risk of fracture decreased when the number of T2D-related risk factors decreased, and the association became non-significant if the T2D patients carried none of the risk factors. In conclusion, the genetically determined T2D might not be associated with higher risk of fracture. And the shared genetic architecture between T2D and fracture suggested a top signal around RSPO3 gene. The observed effect size of T2D on fracture risk decreased if the T2D-related risk factors could be eliminated. Therefore, it is important to manage the complications of T2D to prevent the risk of fracture.

Oxidative coupling of indoles with ethyl 2-(disubstituted amino)acetates: an approach to achieve indolylglycine derivatives.

An efficient method for the synthesis of indolylglycine derivatives is described. The oxidative coupling reactions of ethyl 2-(disubstituted amino)acetates with indoles proceeded smoothly in the presence of meta-chloroperoxybenzoic acid (mCPBA) under ambient conditions to produce indolylglycine derivatives in satisfactory to excellent yields.

Arylglycine-derivative synthesis via oxidative sp(3) C-H functionalization of α-amino esters.

An efficient method for the synthesis of arylglycine derivatives is described. The oxidative coupling reactions of naphthols and phenols with α-amino esters proceeded smoothly in the presence of meta-chloroperoxybenzoic acid as an oxidant under ambient conditions, to produce arylglycine derivatives in satisfactory yields.

Propargylamine synthesis by copper-catalyzed oxidative coupling of alkynes and tertiary amine N-oxides.

An efficient method for synthesizing N,N-dimethylpropargylamines is described. The synthesis exploited the Cu(II)-catalyzed oxidative alkynylation reaction of trimethylamine N-oxides with alkynes in the absence of external oxidant. Both aromatic and aliphatic alkynes were utilized to achieve the corresponding products in moderate to excellent yields. The reaction conditions tolerated ester, hydroxy, and aldehyde groups.

The effect of mix-milling with P2O5 on cellulose physicochemical properties responsible for increased glucose yield.

Breaking the recalcitrant structure of native crystalline cellulose is an energy demanding rate liming step in the production of glucose from cellulosic biomass. Mix-milling of lignocellulosic substrates (with P2O5) dramatically increased glucose yield. In this work, the changes of physicochemical characteristics (morphology, structure, degree of polymerization (DP), solubility) of cellulose during mix-milling (with P2O5) are correlated with glucose yield in the subsequent chemical hydrolysis process. The mix-milling enables highly efficient breakdown of cellulose I crystalline to smaller amorphous particles with low DP, which is recrystallized into cellulose II structure after water-wetting. As a result, the mix-milled cellulose (MMC) shows higher hydrolysis reactivity than that of single-milled cellulose (SMC). The results showed that small particle size, low DP, higher solubility and cellulose II content are correlated with the hydrolysis reactivity of cellulose.

Realizing Fast Charge Diffusion in Oriented Iron Carbodiimide Structure for High-Rate Sodium-Ion Storage Performance.

Iron carbodiimide (FeNCN) belongs to a type of metal compounds with a more covalent bonding structure compared to common transition metal oxides. It could provide possibilities for various structural designs with improved charge-transfer kinetics in battery systems. Moreover, these possibilities are still highly expected for promoting enhancement in rate performance of sodium (Na)-ion battery. Herein, oriented FeNCN crystallites were grown on the carbon-based substrate with exposed {010} faces along the [001] direction (O-FeNCN/S). It provides a high Na-ion storage capacity with excellent rate capability (680 mAh g-1 at 0.2 A g-1 and 360 mAh g-1 at 20 A g-1), presenting rapid charge-transfer kinetics with high contribution of pseudocapacitance during a typical conversion reaction. This high rate performance is attributed to the oriented morphology of FeNCN crystallites. Its orientation along [001] maintains preferred Na-ion diffusion along the two directions in the entire morphology of O-FeNCN/S, supporting fast Na-ion storage kinetics during the charge/discharge process. This study could provide ideas toward the understanding of the rational structural design of metal carbodiimides for attaining high electrochemical performance in future.

Hierarchically urchin-like hollow NiCo2S4 prepared by a facile template-free method for high-performance supercapacitors.

Hollow structures draw much attention for high energy density supercapacitors due to their large hollow cavities, high specific surface area, and low interfacial contact resistance. However, constructing hierarchical hollow structures remains a challenge. Herein, we reported a facile template-free method for a novel urchin-like hollow nickel cobalt sulfide (NiCo2S4). The hollow interior and urchin exterior remarkably improved the specific capacitance and accommodated structural collapse caused by electrochemical reactions. Owing to these features, the urchin-like hollow NiCo2S4 spheres exhibited an impressive capacitance of 1398F g-1 at 1 A g-1 and maintained 1110F g-1 with a large current density of 10 A g-1. The hybrid supercapacitor fabricated by NiCo2S4 and active carbon possesses an energy density of 39.3 Wh kg-1 at a power density of 749.6 W kg-1 and an outstanding cycling stability of 74.4% retention after 5000 cycles. Our work presents a facile method of constructing a hollow structure of binary sulfide materials and also makes progress on highly efficient supercapacitors.

Tremella-like Mo and N Codoped Graphitic Nanosheets by In Situ Carbonization of Phthalocyanine for Potassium-Ion Battery.

A tremella-like Mo and N codoped graphitic nanosheet array supported on activated carbon (Mo2C-MoC/AC-N) is prepared via in situ carbonization of nitrogen-rich cobalt phthalocyanine nanoparticulates anchored on activated carbon as a high-performance anode for potassium-ion batteries. The nanosheets about 5 nm thick are uniformly distributed on the surface of activated carbon for fast K-ion intercalation, and the abundant micropores in activated carbon provide additional adsorption sites of potassium ions, forming a three-dimensional architecture for potassium storage. The 3.9 atom % Mo in Mo2C-MoC/AC-N is in the form of Mo2C and MoC flakes (around 1:1) attached to the graphitic nanosheets. X-ray diffraction (XRD) analysis revealed that the reaction with Mo2C (forming K2C) happens mainly at 0.8-0.4 V, while the reaction with MoC (forming K2C) occurs primarily at 0.4-0.01 V. The N doping (9.6 atom %) causes an interlayer spacing expansion of 0.3 Å in the graphitic nanosheets, beneficial to the potassium-ion insertion reaction to form KC8 at 0.4-0.01 V. The Mo2C-MoC/AC-N anode exhibits a capacity of 457.5 mA h g-1 at a current density of 0.05 A g-1 and an excellent capacity of 144.4 mA h g-1 at a high current of 5 A g-1 with a capacity loss rate of 0.49‰ per cycle.

Mechanistic understanding of humin formation in the conversion of glucose and fructose to 5-hydroxymethylfurfural in [BMIM]Cl ionic liquid.

Humin formation is one of the key issues that hinders economical 5-HMF production from hexose sugars such as glucose and fructose. In this work, the mechanism of humin formation in glucose/fructose conversion to HMF was studied in an ionic liquid system (1-butyl-3-methylimidazolium chloride, [BMIM]Cl) with CrCl3 as the catalyst. Elemental analysis, XRD, FT-IR, and TEM were applied to study the molecular structure and morphology of the solid humins. The possible intermediates to form solid humins were investigated by HPLC-MS. We synthesized furanic model compounds that mimic the experimentally identified humin intermediates to investigate the mechanism of humin growth at an early stage. The results showed that a furan compound bearing a hydroxymethyl and an electron-donating group was unstable due to three types of reactions: (1) bimolecular ether formation reactions; (2) intermolecular addition reaction; (3) furan ring opening reaction with water. The stability of a furan compound in [BMIM]Cl was increased when the hydroxymethyl group of a furan compound was protected by a methyl group, and the stability was further enhanced with an additional electron-withdrawing group (such as an aldehyde group) on the furan ring. Protecting the hydroxymethyl group of 5-HMF with a methyl group allows easy separation of the products from the [BMIM]Cl solvent through extraction.