Understanding the oxidation chemistry of Ti_(3)C_(2)T_(x)(MXene)sheets and their catalytic performances

Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen.Despite the great research progress,the exact oxidation kinetics of Ti_(3)C_(2)T_(x)(MXene)and their final products after oxidation are not fully understood.Herein,we systematically tracked the oxidation process of few-layer Ti_(3)C_(2)T_(x) nanosheets in an aqueous solution at room temperature over several weeks.We also studied the oxidation effects on the electrocatalytic properties of Ti_(3)C_(2)T_(x) for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm^(-2)increases from 0.435 to 0.877 V after three weeks of degradation,followed by improvement to stabilized values of around 0.40 V after eight weeks.These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts.According to our detailed experimental characterization and theoretical calculations,unlike previous studies,black titanium oxide is formed as the final product in addition to white Ti(IV)oxide and disordered carbons after the complete oxidation of Ti_(3)C_(2)T_(x).This work presents significant advancements in better understanding of 2D Ti_(3)C_(2)T_(x)(MXene)oxidation and enhances the prospects of this material for various applications.

Advanced Functional Electromagnetic Shielding Materials:A Review Based on Micro‑Nano Structure Interface Control of Biomass Cell Walls

Research efforts on electromagnetic interference(EMI)shielding materials have begun to converge on green and sustainable biomass materials.These materials offer numerous advantages such as being lightweight,porous,and hierarchical.Due to their porous nature,interfacial compatibility,and electrical conductivity,biomass materials hold significant potential as EMI shielding materials.Despite concerted efforts on the EMI shielding of biomass materials have been reported,this research area is still relatively new compared to traditional EMI shielding materials.In particular,a more comprehensive study and summary of the factors influencing biomass EMI shielding materials including the pore structure adjustment,preparation process,and micro-control would be valuable.The preparation methods and characteristics of wood,bamboo,cellulose and lignin in EMI shielding field are critically discussed in this paper,and similar biomass EMI materials are summarized and analyzed.The composite methods and fillers of various biomass materials were reviewed.this paper also highlights the mechanism of EMI shielding as well as existing prospects and challenges for development trends in this field.

Traditional uses,phytochemistry and pharmacology of Clerodendron glandulosum Coleb - a review

Present review for the first time provides a complete botanical description and information on ethnomcdicinal uses of Clerodendron glandulosum.Coleb(CG:Fam.Verbenaceae).Recent studies conducted from our laborator) provide pharmacological evidence for its anti-hypertensive,antidiabetic and anti-obesity potentials.Further,its beneficial potential in preventing in vitro and in vivo non-alcoholic steatohepatitis and atherosclerosis and potent hcpatoprotective and free radical scavenging abilities along with its acute and sub- chronic toxicologiesl evaluations are also reported from our laboratory.In keeping with its traditional uses,CG extract was capable of ameliorating experimentally induced hypertension,diabetes and obesity.Its beneficial potential against NASH induced oxidative stress and atherosclerosis can be attributed to its potent free radical scavenging potential.Non—toxic nature of CG leaf extract further provides added merit to its reported pharmacological properties.The present review summarizes the pioneering scientific evidence for the pharmacological effects of CG against related metabolic disorders like hypertension,diabetes and obesity along with anti oxidant potential and beneficial elicits against non alcoholic steatohepatitis.

Chemistry under extreme conditions: Pressure evolution of chemical bonding and structure in dense solids

Recent advances in high-pressure technologies and large-scale experimental and computational facilities have enabled scientists,at an unprecedented rate,to discover and predict novel states and materials under the extreme pressure-temperature conditions found in deep,giant-planet interiors.Based on a well-documented body of work in this field of high-pressure research,we elucidate the fundamental principles that govern the chemistry of dense solids under extreme conditions.These include:(i)the pressure-induced evolution of chemical bonding and structure of molecular solids to extended covalent solids,ionic solids and,ultimately,metallic solids,as pressure increases to the terapascal regime;(ii)novel properties and complex transition mechanisms,arising from the subtle balance between electron hybridization(bonding)and electrostatic interaction(packing)in densely packed solids;and(iii)new dense framework solids with high energy densities,and with tunable properties and stabilities under ambient conditions.Examples are taken primarily fromlow-Z molecular systems that have scientific implications for giant-planet models,condensed materials physics,and solid-state core-electron chemistry.

A Quantum Chemistry Study of Inhibition Properties of Imidazole and Its Derivatives on Iron Surface Corrosion

The geometries of imidazole and its derivatives were respectively optimized by using ab initio method, and the molecular orbital energy levels and the charge densities were obtained for their optimum geometries. The frontier orbital energy levels, and the net charges of N (1) atom and the imidazole ring of those molecules were obtained with ab initio and SCC-DV-Xα methods. It was found that the inhibition properties of those compounds change with the highest occupied molecular orbital energy levels, and the net charges of N (1) atom. We took four iron atoms on the crystal plane (100) of α-iron as the surface which was used to study the adsorption towards the inhibitors. The adsorption models of the inhibitor to be adsorbed on the Fe-cluster surface were optimized with SCC-DV-Xα method. It turns out that the most favorable model is that the inhibitor molecule is adsorbed on the Fe-cluster surface in an inclined state. The calculation shows that the stabilization energies of the systems are well correlated with the inhibition efficiencies.

Solvothermal Syntheses, Crystal Structures, Thermal Stability and Quantum Chemistry of Dinuclear Trialkyltin Complexes Constructed by Camphoric Acid

Two dinuclear organotin complexes C8H14（CO2SnCy3）2（1）（Cy = cyclohexyl group） and C8H14[CO2Sn（CH2CMe2Ph）3]2（2） were synthesized by the reactions of camphoric acid with tricyclohexyltin hydroxide and bis[tri（2-methyl-2-phenyl）propyltin] oxide under solvothermal conditions, and these complexes were characterized by infrared spectra, elemental analyses, and H NMR spectra. The crystal of 1 belongs to the monoclinic system, space group P21/c with a = 1.83478（19）, b = 1.52707（18）, c = 1.9849（2） nm, β = 122.515（7）°, Z = 4, V = 4.6896（9） nm^3, Dc = 1.324 g/cm^3, μ（MoKα） = 1.103 mm^-1, F（000） = 1952, R = 0.0697 and wR = 0.2040. In addition, thermal stability and quantum chemical calculation of 1 were also studied.

Recent progress on discovery and properties prediction of energy materials:Simple machine learning meets complex quantum chemistry

In nature,the properties of matter are ultimately governed by the electronic structures.Quantum chemistry(QC)at electronic level matches well with a few simple physical assumptions in solving simple problems.To date,machine learning(ML)algorithm has been migrated to this field to simplify calculations and improve fidelity.This review introduces the basic information on universal electron structures of emerging energy materials and ML algorithms involved in the prediction of material properties.Then,the structure-property relationships based on ML algorithm and QC theory are reviewed.Especially,the summary of recently reported applications on classifying crystal structure,modeling electronic structure,optimizing experimental method,and predicting performance is provided.Last,an outlook on ML assisted QC calculation towards identifying emerging energy materials is also presented.

Conductivity of K_(10)H_3[Dy(SiW_4Mo_7O_(39))_2] Treated by Chemistry-Heated Diffusion of Sm and Gd Permeation

Chemistry-heated diffused permeation was used to treat POMs. ICP, IR, TG-DTA, XPS were used to characterize K_(10)H_3[Dy(SiW_4Mo_7O_(39))_2] and the sample. The result show that Sm and Gd can be permeated into the body of this sample, chemical bonds forming between Sm and other components and the conductivity of K_(10)H_3[Dy(SiW_4Mo_7O_(39))_2] improves by 0 9356×10~4 times.

Thermochemistry on Coordination Behavior of Neodymium Chloride Hydrate with Diethylammonium Diethyldithiocarbamate

The complex of neodymium chloride lower hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized conveniently in absolute alcohol and dry N_2 atmosphere. The title complex was identified as Et_2NH_2[Nd(S_2CNEt_2)_4] by chemical and elemental analyses and the bonding characteristics of which was characterized by IR. The enthalpies of solution of neodymium chloride hydrate and D-DDC in absolute alcohol at 298.15 K and the enthalpies change of liquid-phase reaction of formation for Et_2NH_2[Nd (S_2CNEt_2)_4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of liquid-phase reaction of formation were obtained. The enthalpy change of the solid-phase title reaction at 298.15 K was calculated by a thermochemical cycle.

Geochemistry of Sediments from the Lopare Basin(Bosnia and Herzegovina):Implications for Paleoclimate,Paleosalinity,Paleoredox and Provenance

A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin,Bosnia and Herzegovina.A total of 46 samples collected from two boreholes,Pot 1(depth of 193 m)and Pot 3(depth of 344 m),showed that element abundances like boron(B),lithium(Li),strontium(Sr),uranium(U),chromium(Cr),nickel(Ni),magnesium(Mg),sodium(Na)and calcium(Ca)are much higher than average than in the upper continental crust(UCC).Chemical composition indicates at least two sources:(i)Mesozoic ophiolites occurring in the north of the investigated area,and(ii)dacito-andesitic pyroclastics(Mesozoic to Cenozoic).Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake,which formed during a warm climatic period,probably during the Miocene Climatic Optimum.A brief episode of humid climate conditions resulted in the basin fillingup and deposition of felsic sediments enriched in thorium(Th).Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter(OM).The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data.Conversely,the molecular distribution of n-alkanes as reliable climatic andδ-MTTC as paleosalinity indicators do not support this conclusion.

Synthesis,Crystal Structure and Quantum Chemistry of Dibutyltin 3,4-Dimethoxybenzotate Compound

The dibutyltin 3,4-dimethoxybenzotate compound {[（3,4-（CH3O）2C6H3COO） Sn（Bu-n）2]2O}2 has been synthesized by the reaction of dibutyltin oxide with 3,4-dimethoxybenzoic acid. Its structure was determined by X-ray single-crystal diffraction. The crystal belongs to the triclinic system,space group P1 with a = 1.2003（2）,b = 1.2821（3）,c = 1.3666（3） nm,α = 80.50（3）,β = 65.56（3）,γ = 73.36（3）°,Z = 2,V = 1.8318（6） nm3,Dc = 1.530 Mg·m-3,μ（MoKa） = 1.413 mm-1,F（000） = 860,R = 0.0554 and wR = 0.1092. In the complex,each tin atom adopts a distorted tigonal bipyramidal structure,and the dimer structure is shaped by one Sn2O2 planar four-membered ring. The stabilities of the title complex,along with its orbital energies and composition characteristics of some frontier molecular orbitals have been investigated by means of quantum chemistry calculation methods.

Redox chemistry of N_(4-)Fe^(2+)in iron phthalocyanines for oxygen reduction reaction

A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,three different iron phthalocyanines(FePcs)adsorbed on carbon nanotubes((NH2)4FePc@CNTs,(t-Bu)4FePc@CNTs,and FePc@CNTs)were evaluated to demonstrate the effect of the electron donating power of the substituents on the Fe^(3+)/Fe^(2+)redox potential of FePc@CNTs and the role of these composites as ORR mediators in alkaline media.The Fe^(3+)/Fe^(2+)redox potential of the FePcs was found to shift towards the cathodic region upon substitution with electron-donating groups.This up-field shift in the eg-orbital leads to a lower overlap between the onset potential of the Fe^(3+)/Fe^(2+)redox couple and that of the ORR,and thus,the ORR activity decreased in the following order based on the substitution of FePc:-H>-t-Bu>-NH2.

In-Situ Microscopic FTIR Spectroelectrochemistry of Ascorbic Acid in Poly(ethylene glycol)/LiClO_4 Electrolyte Paste and in the Presence of Dispersed Cobalt Hexacyanoferrate Microcrystalline Powder

In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.

Corrosive electrochemistry of jamesonite

The corrosive electrochemistry of jamesonite (Pb4FeSb6S14) was studied by the electrochemical methods of cyclic voltammetry, polarization, and AC impedance. The electrochemical processes of jamesonite were controlled by the corrosive reactions, growth of the metal-deficient and sulfur-riched layer, passivation and breakdown of elemental sulfur film on the electrode surface. The corrosive potential(φcorr) moves negatively, its corrosive current increases, and hydroxyl action becomes stronger with the rising pH value. The charge transfer resistance increases and the capacitance decreases due to the gradual growth of the metal-deficient and sulfur-riched layer on the mineral surface from -378 to 122 mV （vs SHE）. Element sulfur layer is formed at the potential of 122 mV. The charge transfer resistance increases and its capacitance rises slowly due to the gradual breakdown of sulfur film at voltage from 222 mV to 422 mV. S2O2-3 and SO2-4 ions occur when the electrode potential is over 422 mV. Under basic condition, the hydrophobic hydroxyl precipitate occurs on jamesonite surface, so that its collectorless floatability is poor. Under the condition of pH 6.86, it can be deduced that the potential range of collectorless floatability of jamesonite is from 22 to 422 mV due to the passive action of the hydrophilic sulfur on jamesonite surface, and its optimum range of floatable potential is between 122 and 322 mV.

Recent progress on MOF/MXene nanoarchitectures:A new era in coordination chemistry for energy storage and conversion

The development of urbanization and industrialization leads to rapid depletion of fossil fuels.Therefore,the production of fuel from renewable resources is highly desired.Electrotechnical energy conversion and storage is a benign technique with reliable output and is eco-friendly.Developing an exceptional electrochemical catalyst with tunable properties like a huge specific surface area,porous channels,and abundant active sites is critical points.Recently,Metal-organic frameworks(MOFs)and two-dimensional(2D)transition-metal carbides/nitrides(MXenes)have been extensively investigated in the field of electrochemical energy conversion and storage.However,advances in the research on MOFs are hampered by their limited structural stability and conventionally low electrical conductivity,whereas the practical electrochemical performance of MXenes is impeded by their low porosity,inadequate redox sites,and agglomeration.Consequently,researchers have been designing MOF/MXene nanoarchitectures to overcome the limitations in electrochemical energy conversion and storage.This review explores the recent advances in MOF/MXene nanoarchitectures design strategies,tailoring their properties based on the morphologies(0D,1D,2D,and 3D),and broadening their future opportunities in electrochemical energy storage(batteries,supercapacitors)and catalytic energy conversion(HER,OER,and ORR).The intercalation of MOF in between the MXene layers in the nanoarchitectures functions synergistically to address the issues associated with bare MXene and MOF in the electrochemical energy storage and conversion.This review gives a clear emphasis on the general aspects of MOF/MXene nanoarchitectures,and the future research perspectives,challenges of MOF/MXene design strategies and electrochemical applications are highlighted.

Lewis-base Adducts of Lead(Ⅱ) Compounds:Synthesis, Structure and Quantum Chemistry Calculation of Mononuclear Pb(phen)(SCN)_2

The lead thiocyanate adduct Pb(phen)(SCN)2 (phen = 1,10-phenanthroline) has been prepared by a direct synthetic method and structurally characterized. It presents a mononuclear structure and crystallizes in monoclinic, space group C2/c with a = 17.505(4), b = 13.383(3), c = 6.7916(14) ?, β = 112.25(3)o, V = 1472.6(6) ?3, Z = 4, Dc = 2.271 g/cm3, μ(MoKα) = 11.737 mm-1, F(000) = 936, C14H8N4PbS2, Mr = 503.58, the final R = 0.0446 and wR = 0.1034 for 1601 observed reflections with I > 2σ(I). Structure analysis showed that the lead atom presents an unusual four- coordination geometry with a large vacancy, possibly indicating the stereochemical activity of 6s2 lone pair electrons.

Reversible electrochemistry of DNA on multi-walled carbon nanotube modified electrode

Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues,respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans.

Synthesis, Crystal Structure and Electrochemistry Properties of a (N,N'-Ethylene-bis(salicylaldiminato)) Nickel(II) Complex, [Ni_2(salen)_2]·NCS·NH_4

A new Ni（Ⅱ） complex [Ni2（salen）2]·（NCS）·NH4 （salen = N,N＇-bis（salicylideneamino）ethanato） has been prepared and structurally characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 16.8725（13）, b = 19.0046（15）, c = 20.0583（16）A, Z = 8, V = 6431.8（9）A^3, C33H32N6Ni2O4S1, Mr = 726.13, Dc = 1.500 g/cm^3, F（000） = 3008, μ = 1.284 mm^-1, the final R = 0.0394 and wR = 0.0767 for 4449 observed reflections with I 〉 2σ（I）. The complex involves a N,N＇-ethylene-bis（salicylaldiminato） Schiff base, an isothiocyanato anion and an ammonium cation. The nickle（II） ion adopts a distorted square coordination geometry with N2O2 set of Schiff base ligand. The complexes are linked into a dimmer via intermolecular hydrogen bonds and the [Ni（salen）] moieties are connected together to form a 2-D layer structure by intermolecular N-H…O hydrogen bonds and π-π stacking. Cyclic-voltammetry method was used to characterize electrochemically the complex.

Synthesis,Structure,Electrochemistry and Fluorescence Properties of a One-dimensional Coordination Polymer {[Cd[μ-(4,4′-dps)]_2(H_2O)_2]·(4-abs)_2(H_2O)_2}_n

A new cadmium（N） compound, {[ CdLu-（4,4＇-dps） ]2（H2O）2]＇（4＇abs ）2（H2O）2n 1 （4,4＇-dps = 4,4＇-dipyridylsulfide, 4-abs = deprotonated 4-amino benzenesulfonic acid）, has been synthesized and structurally characterized. It belongs to the orthorhombic system, space group Pbcn with a = 19.950（3）, b = 10.6381（13）, c = 18.055（2）A, V= 3831.8（8） A3, Z = 4, C32H36CdN6010S4, Mr = 905.31, F（000） = 1848, μ= 0.850 mm^-1, Dc = 1.569 Mg/m^3, the final R = 0.0238 and wR = 0.0589 for 3080 observed reflections with I 〉 2σ（I）. Complex I is a one-dimensional linear chain coordination polymer and the repeat unit is comprised of doubly charged cadmium complex cation, uncoordinated 4-aminobenzene sulfonate anions and water molecules. The cadmium（H） ion adopts a six-coordinate distorted octahedral geometry. Complex 1 is stabilized and linked into a three-dimensional layered structure through intermolecular O-H…O and N-H…O hydrogen bonds together with electrostatic force. The cyclic voltammograms and fluorescence spectrum of 1 were also measured. It shows one irreversible redox process and emits a very strong and sharp fluorescent band at about 341 nm.

Synthesis and Structural Chemistry of Two Novel Transition Metal Organic Phosphonates

Two novel transition metal phosphonate compounds, [Co（H2BDPP）（phen）]n 1 （BDPP = p-O3PCH2（C6H4）CH2PO3, phen = 1,10-phenanthroline） and [Pb3（BCP）2]n 2 （BCP = OOC（C6H4）CH2PO3）, have been synthesized and structurally determined by X-ray single-crystal diffraction. Compound 1 crystallizes in the monoclinic system, space group C2/c with a = 21.169（4）, b = 12.001（2）, c = 7.6211（15）A, β = 98.03（3）°, V= 1917.2（6）A^3, C20H18N2O6P2Co, Mr = 505.22, Z = 8, De= 1.737 g/cm^3, p = 1.107 mm^-1, F（000） = 1020, the final R= 0.0450 and wR = 0.1306 for 2072 observed reflections （I 〉 2σ（I）. Compound 2 crystallizes in the monoclinic system, space group C2/c with a = 4.7167（9）, b = 18.753（2）, c = 22.781（3）A, β = 91.07（3）°, V= 2014.7（14）A^, C8H6O5PPb1.5, Mr = 523.88, Z = 8, Dc = 3.454 g/cm^3, p = 25.222 mm^-1, F（000） = 1856, the final R = 0.0441 and wR = 0.1906 for 2259 observed reflections （I 〉 2σ（I）. In compound 1, the 1D chain running along the c axis is bridged by four ligands （trans- HO3PCH2C6H4CH2PO3H） in four different directions to extend the structure into a three- dimensional network. In compound 2, the Pb（II） displays 4- and 5-coordination modes. There is a one-dimensional P-O-Pb band along the a axis formed by PO3 groups and Pb（II） cations. These bands are joined by μ2-O of -COO to yield two-dimensional inorganic P-O-Pb layers which are pillared by the OOCC6HaCH2PO3 ligands to form a three-dimensional network. Moreover, compound 2 displays a strong emission band attributed to the ligand-centered （LC） transition.