An Active Strategy to Reduce Residual Alkali for High-Performance Layered Oxide Cathode Materials of Sodium-Ion Batteries.

Residual alkali is one of the biggest challenges for the commercialization of sodium-based layered transition metal oxide cathode materials since it can even inevitably appear during the production process. Herein, taking O3-type Na0.9Ni0.25Mn0.4Fe0.2Mg0.1Ti0.05O2 as an example, an active strategy is proposed to reduce residual alkali by slowing the cooling rate, which can be achieved in one-step preparation method. It is suggested that slow cooling can significantly enhance the internal uniformity of the material, facilitating the reintegration of Na+ into the bulk material during the calcination cooling phase, therefore substantially reducing residual alkali. The strategy can remarkably suppress the slurry gelation and gas evolution and enhance the structural stability. Compared to naturally cooled cathode materials, the capacity retention of the slowly cooled electrode material increases from 76.2% to 85.7% after 300 cycles at 1 C. This work offers a versatile approach to the development of advanced cathode materials toward practical applications.

Exploitation of multiple host-derived nutrients by the yellow catfish epidermal environment facilitates Vibrio mimicus to sustain infection potency and susceptibility.

Infection with Vibrio mimicus in the Siluriformes has demonstrated a rapid and high infectivity and mortality rate, distinct from other hosts. Our earlier investigations identified necrosis, an inflammatory storm, and tissue remodeling as crucial pathological responses in yellow catfish (Pelteobagrus fulvidraco) infected with V. mimicus. The objective of this study was to further elucidate the impact linking these pathological responses within the host during V. mimicus infection. Employing metabolomics and transcriptomics, we uncovered infection-induced dense vacuolization of perimysium; Several genes related to nucleosidase and peptidase activities were significantly upregulated in the skin and muscles of infected fish. Concurrently, the translation processes of host cells were impaired. Further investigation revealed that V. mimicus completes its infection process by enhancing its metabolism, including the utilization of oligopeptides and nucleotides. The high susceptibility of yellow catfish to V. mimicus infection was associated with the composition of its body surface, which provided a microenvironment rich in various nucleotides such as dIMP, dAMP, deoxyguanosine, and ADP, in addition to several amino acids and peptides. Some of these metabolites significantly boost V. mimicus growth and motility, thus influencing its biological functions. Furthermore, we uncovered an elevated expression of gangliosides on the surface of yellow catfish, aiding V. mimicus adhesion and increasing its infection risk. Notably, we observed that the skin and muscles of yellow catfish were deficient in over 25 polyunsaturated fatty acids, such as Eicosapentaenoic acid, 12-oxo-ETE, and 13-Oxo-ODE. These substances play a role in anti-inflammatory mechanisms, possibly contributing to the immune dysregulation observed in yellow catfish. In summary, our study reveals a host immune deviation phenomenon that promotes bacterial colonization by increasing nutrient supply. It underscores the crucial factors rendering yellow catfish highly susceptible to V. mimicus, indicating that host nutritional sources not only enable the establishment and maintenance of infection within the host but also aid bacterial survival under immune pressure, ultimately completing its lifecycle.

Computational understanding of Na-LTA for ethanol-water separation.

There is a growing demand for high purity ethanol as an electronic chemical. The conventional distillation process is effective for separating ethanol from water but consumes a significant amount of energy. Selective membrane separation using the LTA-type molecular sieve has been introduced as an alternative. The density functional theory simulation indicates that aluminum (Al) sites are evenly distributed throughout the framework, while sodium (Na+) ions are preferentially located in the six-membered ring. The movement of ethanol molecules can cause Na+ ions to be transported towards the eight-membered ring, hindering the passage of ethanol through the channel. In contrast, the energy barrier for water molecules passing through the channel occupied by Na+ ions is significantly lower, leading to a high level of selectivity for ethanol-water separation.

Toluene Tolerated Li9.88GeP1.96Sb0.04S11.88Cl0.12 Solid Electrolyte toward Ultrathin Membranes for All-Solid-State Lithium Batteries.

Sulfide solid electrolyte membranes employed in all-solid-state lithium batteries generally show high thickness and poor chemical stability, which limit the cell-level energy density and cycle life. In this work, Li9.88GeP1.96Sb0.04S11.88Cl0.12 solid electrolyte is synthesized with Sb, Cl partial substitution of P, S, possessing excellent toluene tolerance and stability to lithium. The formed SbS43- group in Li9.88GeP1.96Sb0.04S11.88Cl0.12 exhibits low adsorption energy and reactivity for toluene molecules, confirmed by first-principles density functional theory calculation. Using toluene as the solvent, ultrathin Li9.88GeP1.96Sb0.04S11.88Cl0.12 membranes with adjustable thicknesses can be well prepared by the wet coating method, and an 8 µm thick membrane exhibits an ionic conductivity of 1.9 mS cm-1 with ultrahigh ionic conductance of 1860 mS and ultralow areal resistance of 0.68 Ω cm-2 at 25 °C. The obtained LiCoO2|Li9.88GeP1.96Sb0.04S11.88Cl0.12 membrane|Li all-solid-state lithium battery shows an initial reversible capacity of 125.6 mAh g-1 with a capacity retention of 86.3% after 250 cycles at 0.1 C under 60 °C.

Dual Atoms (Fe, F) Co-Doping Inducing Electronic Structure Modulation of NiO Hollow Flower-Spheres for Enhanced Oxygen Evolution/Sulfion Oxidation Reaction Performance.

Heteroatoms Fe, F co-doped NiO hollow spheres (Fe, F-NiO) are designed, which simultaneously integrate promoted thermodynamics by electronic structure modulation with boosted reaction kinetics by nano-architectonics. Benefiting from the electronic structure co-regulation of Ni sites by introducing Fe and F atoms in NiO , as the rate-determined step (RDS), the Gibbs free energy of OH* intermediates (ΔGOH* ) for Fe, F-NiO catalyst is significantly decreased to 1.87 eV for oxygen evolution reaction (OER) compared with pristine NiO (2.23 eV), which reduces the energy barrier and improves the reaction activity. Besides, densities of states (DOS) result verifies the bandgap of Fe, F-NiO(100) is significantly decreased compared with pristine NiO(100), which is beneficial to promote electrons transfer efficiency in electrochemical system. Profiting by the synergistic effect, the Fe, F-NiO hollow spheres only require the overpotential of 215 mV for OER at 10 mA cm-2 and extraordinary durability under alkaline condition. The assembled Fe, F-NiO||Fe-Ni2 P system only needs 1.51 V to reach 10 mA cm-2 , also exhibits outstanding electrocatalytic durability for continuous operation. More importantly, replacing the sluggish OER by advanced sulfion oxidation reaction (SOR) not only can realize the energy saving H2 production and toxic substances degradation, but also bring additional economic benefits.

Ligand Defect Density Regulation in Metal-Organic Frameworks by Functional Group Engineering on Linkers.

Defects in solid materials vitally determine their physicochemical properties; however, facile regulation of the defect density is still a challenge. Herein, we demonstrate that the ligand defect density of metal-organic frameworks (MOFs) with a UiO-66 structural prototype is precisely regulated by tuning the linker groups (X = OMe, Me, H, F). Detailed analyses reveal that the ligand defect concentration is positively correlated with the electronegativity of linker groups, and Ce-UiO-66-F, constructed by F-containing ligands and Ce-oxo nodes, possesses the superior ligand defect density (>25%) and identifiable irregular periodicity. The increase in ligand defect density results in the reduction of the valence state and the coordination number of Ce sites in Ce-UiO-66-X, and this merit further validates the relationship between the defective structure and catalytic performance of CO2 cycloaddition reaction. This facile, efficient, and reliable strategy may also be applicable to precisely constructing the defect density of porous materials in the future.

Atomically Dispersed Dual Metal Sites Boost the Efficiency of Olefins Epoxidation in Tandem with CO2 Cycloaddition.

Tandem catalysis provides an economical and energy-efficient process for the production of fine chemicals. In this work, we demonstrate that a rationally synthesized carbon-based catalyst with atomically dispersed dual Fe-Al sites (ADD-Fe-Al) achieves superior catalytic activity for the one-pot oxidative carboxylation of olefins (conversion ∼97%, selectivity ∼91%), where the yield of target product over ADD-Fe-Al is at least 62% higher than that of monometallic counterparts. The kinetic results reveal that the excellent catalytic performance arises from the synergistic effect between Fe (oxidation site) and Al sites (cycloaddition site), where the efficient CO2 cycloaddition with epoxides in the presence of Al sites (3.91 wt %) positively shifts the oxidation equilibrium to olefin epoxidation over Fe sites (0.89 wt %). This work not only offers an advanced catalyst for oxidative carboxylation of olefins but also opens up an avenue for the rational design of multifunctional catalysts for tandem catalytic reactions in the future.

Theoretical Screening of Transition Metal Doped Defective MoS2 as Efficient Electrocatalyst for CO Conversion to CH4.

CO is a key intermediate during electrochemical CO2 conversion. The deep reduction of CO to value-added chemical products is a crucial strategy for effective carbon utilization. Single transition metal atoms supported by two-dimensional material present a novel paragon for various catalytic reactions. Herein, we employ first principle theory to study a series of single 3d-transition metal atoms supported by monolayered MoS2 with S vacancy as efficient electrocatalyst for CO electroreduction to CH4 . The screening result indicates that Cr doped defective MoS2 (labeled as Cr/Sv -MoS2 ) is beneficial to electroreduction of CO to CH4 , with even less negative limiting potential (-0.32 V) than Cu that has been widely studied as the most promising electrocatalyst in experiment. The outstanding activity is derived from the regulation of the d-band-center of doped Cr and Mo atoms exposed on the surface. This discovery provides a theoretical basis for the preparation of future electrocatalysts for CORR.

Structural Evolution of Graphitic Carbon Derived from Ionic Liquids-Dissolved Cellulose and Its Application as Lithium-Ion Battery Anodes.

With an attempt to replace petroleum-derived commercial graphite (CG) with biomass-derived carbon, microcrystalline cellulose (MCC) dissolved in 1-butyl-3-methylimidazolium acetate (BMIMAcO) was facilely carbonized to prepare cellulose-derived carbon under a low-temperature range of 250-1600 °C. TEM and AFM results revealed structural evolution of carbon nanosheets starting from carbon dots. The XRD and Raman results showed that the degree of crystallinity of the MCC-derived carbon was apparently enhanced as the temperature was increased to 93.02% at 1600 °C, while the XPS results revealed that the nitrogen content was greatly reduced with increasing temperature. BMIMAcO not only induced low-temperature graphitization of MCC-derived carbon but also provided nitrogen doping for the carbon. Used as an anode of lithium-ion batteries (LIBs), the carbon synthesized at 750 °C showed the best cyclic stability and reversible capacity (1052.22 mAh g-1 at 0.5 A g-1 after 100 cycles and 1017.46 mAh g-1 at 1 A g-1 after 1000 cycles) compared to other MCC-derived carbon and CG. In addition, the costs of cellulose-derived carbon are much lower than those of the petroleum-derived graphite, showing environmental and economical merits for LIB anode production.

Dialytic Synthesis of Two-Dimensional Cu-Based Metal-Organic Frameworks for Gas Separation: Designable MOF-Polymer Interface.

We demonstrate a dialytic strategy for the synthesis of congeneric two-dimensional metal-organic framework (2D MOF) nanosheets with a dialysis membrane using 1,4-benzenedicarboxylic acid (BDC), 1,4-naphthalenedicarboxylic acid (NDC), and 9,10-anthracenedicarboxylic acid (ADC) as organic linkers and copper(II) as a metal precursor, respectively. Polyimide (PI) membranes containing these empty 2D MOF nanosheets exhibit distinct molecular sieve effects. Molecular dynamic simulation results reveal that the structures of MOF-polymer interfaces are designable by modifying the MOF interlayer distance and aperture size, which has significant influences on gas permeability and selectivity. As a result, Cu-NDC/PI with the moderate composite interface structure shows superior performance toward H2/CH4 and CO2/CH4 separations with a selectivity of 199 and 63 over Cu-BDC (121 and 53) and Cu-ADC (135 and 54), respectively.

Theoretical investigation of single-atom catalysts anchored on pure carbon substrate for electroreduction of NO to NH3.

NO electrochemical reduction (NOER) can convert harmful NO pollutants into useful NH3 under ambient conditions, and thus is attracting increasing interest. With density functional theory calculations, we investigated a series of single transition metal (TM) atoms (Sc to Au) located on a pure carbon substrate C558 (TM@C558), as a potential electrocatalyst for NOER. The C558 substrate could stabilize the TM atom with delocalized π electrons, and activate TM atoms via charge transfer. Cu, Ag and Au doped systems are picked out with low limiting potentials for NOER and the inhibition of side reactions. The outstanding activities of Cu-, Ag- and Au@C558 systems are related to their appropriate d band centers and the moderate adsorption intensities of intermediates. Based on the simulations, a volcano relationship between NO binding energy and predicted activity is reported. After simulating the stability of these three single-atom catalysts, Au@C558 is finally regarded as the most promising NOER electrocatalyst with high stability. This work is expected to help with the discovery of novel NOER electrocatalysts in future experiments.

In Situ Anchoring Polymetallic Phosphide Nanoparticles within Porous Prussian Blue Analogue Nanocages for Boosting Oxygen Evolution Catalysis.

The controllable synthesis of metal-based nanoclusters for heterogeneous catalytic reactions has received considerable attention. Nevertheless, manufacturing these architectures, while avoiding aggregation and retaining surface activity, remains challenging. Herein, for the first time we designed NiCoFe-Prussian blue analogue (PBA) nanocages as a support for in situ dispersion and anchoring of polymetallic phosphide nanoparticles (pMP-NPs). Benefiting from the porous surfaces and the synergistic effects between pMP-NPs and the cyano groups in PBA, the NiCoFe-P-NP@NiCoFe-PBA nanocages exhibit a significantly enhanced catalytic activity for oxygen evolution reaction (OER) with an overpotential of 223 mV at 10 mA cm-2 and a Tafel slope of 78 mV dec-1, outperforming the NiCoFe-PBA nanocubes, NiCoFe-P nanocages, NiFe-P-NP@NiFe-PBA nanocubes, and CoFe-P-NP@CoFe-PBA nanoboxes. This work not only offers the synthesis strategy of in situ anchoring pMP-NPs on PBA nanocages but also provides a new insight into optimized Gibbs free energy of OER by regulating electron transfer from metallic phosphides to PBA substrate.

Theoretical investigation of defective MXenes as potential electrocatalysts for CO reduction toward C2 products.

Electrochemical CO2/CO conversion to valuable chemical products is an attractive strategy for storage of clean energy and control of greenhouse gas emission. Currently, CO2 reduction to CO is relatively mature, whereas the deep reduction and further conversion of CO into multi-carbon products, such as ethylene (C2H4) and ethanol (C2H5OH), are highly challenging. Based on the density functional theory (DFT) calculations, we explored the possibility of CO reduction reaction (CORR), to obtain C2 products, with defective MXenes in which the defect is created by removing two neighboring oxygen atoms on the surface. Our results revealed that the dual-oxygen vacancy in defective Mo2TiC2O2 (labeled as Mo2TiC2O2-2OV) can offer a unique environment that confines and enriches the active *COH species, significantly promoting the reduction process as well as C-C bond coupling. The thermodynamic barrier of the potential-determining step (PDS) for Mo2TiC2O2-2OV is 0.32 eV with promising selectivity of C2 products over the competing hydrogen evolution reaction (HER). This work provides a feasible strategy for designing MXene-based electrocatalysts for highly efficient CO2/CO reduction to C2 products.

The Critical Role of Additive Sulfate for Stable Alkaline Seawater Oxidation on Nickel-Based Electrodes.

Seawater electrolysis to produce hydrogen is a critical technology in marine energy projects; however, the severe anode corrosion caused by the highly concentrated chloride is a key issue should be addressed. In this work, we discover that the addition of sulfate in electrolyte can effectively retard the corrosion of chloride ions to the anode. We take nickel foam as the example and observe that the addition of sulfate can greatly improve the corrosion resistance, resulting in prolonged operating stability. Theoretical simulations and in situ experiments both demonstrate that sulfate anions can be preferentially adsorbed on anode surface to form a negative charge layer, which repulses the chloride ions away from the anode by electrostatic repulsion. The repulsive effect of the adsorbed sulfate is also applicable in highly-active catalyst (nickel iron layered double hydroxide) on nickel foam, which shows ca. 5 times stability of that in traditional electrolyte.

Theoretical Framework of 1,3-Thiazolium-5-Thiolates Mesoionic Compounds: Exploring the Nature of Photophysical Property and Molecular Nonlinearity.

Inspired by a previous experimental study on the first-order hyperpolarizabilities of 1,3-thiazolium-5-thiolates mesoionic compounds using the hyper-Rayleigh scattering technique, we theoretically investigated the UV-vis absorption spectra and every-order polarizabilities of these mesoionic molecules. Based on the fact that the photophysical and nonlinear properties observed in the experiment can be perfectly replicated, our theoretical calculations explored the essential characteristics of the optical properties of the mesoionic compounds with different electron-donating groups at the level of electronic structures through various wave function analysis methods. The influence of the electron-donating ability of the donor on the optical properties of the molecules and the contribution of the mesoionic ring moiety to their optical nonlinearity are clarified, which have not been reported by any research so far. This work will help people understand the nature of optical properties of mesoionic-based molecules and provide guidance for the rational design of molecules with excellent photoelectric performance in the future.

Ion-Gated Gas Separation through Porous Graphene.

Porous graphene holds great promise as a one-atom-thin, high-permeance membrane for gas separation, but to precisely control the pore size down to 3-5 Å proves challenging. Here we propose an ion-gated graphene membrane comprising a monolayer of ionic liquid-coated porous graphene to dynamically modulate the pore size to achieve selective gas separation. This approach enables the otherwise nonselective large pores on the order of 1 nm in size to be selective for gases whose diameters range from 3 to 4 Å. We show from molecular dynamics simulations that CO2, N2, and CH4 all can permeate through a 6 Å nanopore in graphene without any selectivity. But when a monolayer of [emim][BF4] ionic liquid (IL) is deposited on the porous graphene, CO2 has much higher permeance than the other two gases. We find that the anion dynamically modulates the pore size by hovering above the pore and provides affinity for CO2, while the larger cation (which cannot go through the pore) holds the anion in place via electrostatic attraction. This composite membrane is especially promising for CO2/CH4 separation, yielding a CO2/CH4 selectivity of about 42 and CO2 permeance of ∼105 GPU (gas permeation unit). We further demonstrate that selectivity and permeance can be tuned by the anion size, pore size, and IL thickness. The present work points toward a promising direction of using the atom-thin ionic liquid/porous graphene hybrid membrane for high-permeance, selective gas separation that allows a greater flexibility in substrate pore size control.

Selective Charging Behavior in an Ionic Mixture Electrolyte-Supercapacitor System for Higher Energy and Power.

Ion-ion interactions in supercapacitor (SC) electrolytes are considered to have significant influence over the charging process and therefore the overall performance of the SC system. Current strategies used to weaken ionic interactions can enhance the power of SCs, but consequently, the energy density will decrease due to the increased distance between adjacent electrolyte ions at the electrode surface. Herein, we report on the simultaneous enhancement of the power and energy densities of a SC using an ionic mixture electrolyte with different types of ionic interactions. Two types of cations with stronger ionic interactions can be packed in a denser arrangement in mesopores to increase the capacitance, whereas only cations with weaker ionic interactions are allowed to enter micropores without sacrificing the power density. This unique selective charging behavior in different confined porous structure was investigated by solid-state nuclear magnetic resonance experiments and further confirmed theoretically by both density functional theory and molecular dynamics simulations. Our results offer a distinct insight into pairing ionic mixture electrolytes with materials with confined porous characteristics and further propose that it is possible to control the charging process resulting in comprehensive enhancements in SC performance.

Highly Efficient Carbon Monoxide Capture by Carbanion-Functionalized Ionic Liquids through C-Site Interactions.

A novel method for the highly efficient and reversible capture of CO in carbanion-functionalized ionic liquids (ILs) by a C-site interaction is reported. Because of its supernucleophilicity, the carbanion in ILs could absorb CO efficiently. As a result, a relatively high absorption capacity for CO (up to 0.046 mol mol-1 ) was achieved under ambient conditions, compared with CO solubility in a commonly used IL [Bmim][Tf2 N] (2×10-3  mol mol-1 ). The results of quantum mechanical calculations and spectroscopic investigation confirmed that the chemical interaction between the C-site in the carbanion and CO resulted in the superior CO absorption capacities. Furthermore, the subsequent conversion of captured CO into valuable chemicals with good reactivity was also realized through the alkoxycarbonylation reaction under mild conditions. Highly efficient CO absorption by carbanion-functionalized ILs provides a new way of separating and converting CO.

The N-B Interaction through a Water Bridge: Understanding the Chemoselectivity of a Fluorescent Protein Based Probe for Peroxynitrite.

Boronic acid and esters have been extensively utilized for molecular recognition and chemical sensing. We recently reported a genetically encoded peroxynitrite (ONOO(-))-specific fluorescent sensor, pnGFP, based on the incorporation of a boronic acid moiety into a circularly permuted green fluorescent protein (cpGFP) followed by directed protein evolution. Different from typical arylboronic acids and esters, the chromophore of pnGFP is unreactive to millimolar concentrations of hydrogen peroxide (H2O2). The focus of this study is to explore the mechanism for the observed unusual chemoselectivity of pnGFP toward peroxynitrite over hydrogen peroxide by using site-directed mutagenesis, X-ray crystallography, (11)B NMR, and computational analysis. Our data collectively support that a His residue on the protein scaffold polarizes a water molecule to induce the formation of an sp(3)-hybridized boron in the chromophore, thereby tuning the reactivity of pnGFP with various reactive oxygen and nitrogen species (ROS/RNS). Our study demonstrates the first example of tunable boron chemistry in a folded nonnative protein, which offers wide implications in designing selective chemical probes.

Comparative Reaction Diagrams for the SN(2) Reaction Formulated According to the Leffler Analysis and the Hammond Postulate.

The Hammond Postulate and the Leffler analysis have provided a cornerstone in the understanding of reaction processes in organic chemistry for over 60 years, yet quantitative applications of these methodologies over the range of reactions envisaged in the original works remain elusive. In the present paper, we analyze a series of SN2 reactions in three solvents that lead to endothermic and exothermic reaction processes, and we show that within the hybridization reaction coordinate the SN2 reaction is fully consistent with both treatments. We give new presentations of the reaction energies as a function of reaction progress, which allow the generation of unified reaction coordinate diagrams that show a linear relationship between the hybridization metric of reaction progress and the relative energies of the stationary points on the potential surface as a function of structure and solvent as originally envisaged by Leffler and Hammond.