锡酸四丁醋[Sn（OBu^n）4]水解缩合实验研究

本文通过锡酸四丁酯[Sn(OBu^n)4]Sos-Gel过程中溶胶稳定性，acacH稳定剂作用，催化剂,pH影响及胶体系系流变学测量，提出acacH的螯合中间体Sn(OBu^n2)(acac)2稳定机理，催化作用机理，流变学测量发现溶胶特性粘度[η]很好地符合近似线性模型，单体官能度f=2.0SnO2胶粒为近似线性分子链，分型维度D＝1．80，分形结构介于SAW链和无规高期链之间，为螯合中间体Sn(OBu^n)2(acac)2的存在提供了实验证据。     

Ultrafine Sn nanocrystals in a hierarchically porous N-doped carbon for lithium ion batteries

We report a simple method of preparing a high performance,Sn-based anode material for lithium ion batteries (LIBs).Adding H2O2 to an aqueous solution containing Sn2+ and aniline results in simultaneous polymerization of aniline and oxidation of Sn2+ to SnO2,leading to a homogeneous composite of polyaniline and SnO2.Hydrogen thermal reduction of the above composite yields N-doped carbon with hierarchical porosity and homogeneously distributed,ultrafine Sn particles.The nanocomposite exhibits excellent performance as an anode material for lithium ion batteries,showing a high reversible specific capacity of 788 mAh·g-1 at a current density of 100 mA·g-1 after 300 cycles and very good stability up to 5,000 mA·g-1.The simple preparation method combined with the good electrochemical performance is highly promising to promote the application of Sn based anode materials.     

Nonlinear Electrical Properties of SnO2—LiO—Nb2O5 Varistor System

The electrical properties of (Nb,Li)-doped SnO2 ceramics as a new varistor material were investigated.The sample 97.95% SnO20.50%Li2O0.05%Nb2O5( mol fraction)sintered at 1450℃ possess the highest density(p=6.77g/cm^3) and nonlinear electrical coefficient(α=11.6).The substitution of Sn^4 with Li^ increases the concentration of oxygen vacancies,together with the formation of solid solution ,which will increase the sintering rate greatly and decrease the optimized sintering temperature.The substitution of Sn^4 with Li^ and the variation of temperature play very important effects on the densities,dielectric constant,nonlinear electrical properties and other characteristics of the samples.The properties of the grain boundary barrier and the microstructural characteristics were investigated to ensure the effect of the dopants and the temperature.A grain boundary defect barrier model was used to illustrate the grain boundary barriers formation in SnO2-Li2O-Nb2O5 varistors.     

Enhancement of the Photoelectric Performance of Dye-sensitized Solar Cells by Sol-gel Modified TiO2 Films

Modified TiO2 films have been prepared by combining commercial titania powders (Degussa P25) with sol-gel made by titanium chloride (Ti-sol). The result shows that clusters are formed by nanoparticles and large pores can be seen on the surface of the TiO2 films. The short circuit photocurrent density and photoelectric conversion efficiency of the solar cells are obviously enhanced compared with those without modification. The relationship between the photoelectric conversion efficiency and the amount of Ti-sol was investigated. With the addition of 30 wt% Ti-sol, the photoelectric conversion efficiency as high as 9.75% is achieved, increasing by 28.3% compared with the solar cells without modification.     

Sol-gel Preparation and Preliminary in vitro Evaluation of Fluorapatite／Hydroxyapatite Solid Solution Films

Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2-4H20 and PO(OH)x(OEt)3-x were selected as precursors, and hexafluorophosphoric acid (HPFo) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPFo to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.     

Prolonged lifetime and enhanced separation of photogenerated charges of nanosized α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> by coupling SnO<Subscript>2</Subscript> for efficient visible-light photocatalysis to convert CO<Subscript>2</Subscript> and degrade acetaldehyde

To develop efficient visible-light photocatalysis on α-Fe2O3,it is highly desirable to promote visible-light-excited high-energy-level electron transfer to a proper energy platform thermodynamically.Herein,based on the transient-state surface photovoltage responses and the atmosphere-controlled steady-state surface photovoltage spectra,it is demonstrated that the lifetime and separation of photogenerated charges of nanosized α-Fe2O3 are increased after coupling a proper amount of nanocrystalline SnO2.This naturally leads to greatly improved photocatalytic activities for CO2 reduction and acetaldehyde degradation.It is suggested that the enhanced charge separation results from the electron transfer from α-Fe2O3 to SnO2,which acts as a proper energy platform.Based on the photocurrent action spectra,it is confirmed that the coupled SnO2 exhibits longer visible-light threshold wavelength (～590 nm) compared with the coupled TiO2 (～550 nm),indicating that the energy platform introduced by SnO2 would accept more photogenerated electrons from α-Fe2O3.Moreover,electrochemical reduction experiments proved that the coupled SnO2 possesses better catalytic ability for reducing CO2 and O2.These are well responsible for the much efficient photocatalysis on SnO2-coupled α-Fe2O3.     

High Pressure Behavior of 4-Amino-3,7-dinitrotriazolo-［5,1,c］ ［1,2,4］triazine Crystal: a DFT Investigation

The effect of external pressure on 4-amino-3,7-dinitrotriazolo-［5,1,c］［1,2,4］ triazine (ADT) crystal in the pressure range of 0-130 GPa was investigated by the density functional theory (DFT) periodic calculation with LDA/CA-PZ function. With the increasing pressure, the volume of ADT crystal decreases while the energy increases. The topological analysis shows that the energy of hydrogen bonds increases as the pressure increases. At 81 GPa, hydrogen bonding between atoms O2 and H5 converts into covalent interaction. And the covalent interaction is formed between atoms N4 and H6. At 82 GPa, the interaction between atoms O2 and H5, N4 and H6 become hydrogen bonding. At 92 GPa, H6…N4 turns into a covalent bond, and there is s covalence interaction between the two atoms. The band gap decreases first and then increases with the increasing pressure.     

Growth of Carbon Nanocoils by Porous α-Fe2O3/SnO2 Catalyst and Its Buckypaper for High Efficient Adsorption

High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.     

Multivalent Sn species synergistically favours the CO2-into-HCOOH conversion

Although Sn-based catalysts have recently achieved considerable improvement in selective electro-catalyzing CO₂into HCOOH,the role of various valence Sn species is not fully understood due to the complexity and uncertainty of their evolution during the reaction process.Here,inspired by the theoretical simulations that the concomitant multivalent Sn(Sn⁰,Sn^Ⅱand Sn^Ⅳ)can significantly motivate the intrinsic activity of Sn-based catalyst,the Sn/SnO/SnO₂nanosheets were proposed to experimentally verify the synergistic effect of multivalent Sn species on the CO₂-into-HCOOH conversion.During CO₂reduction reaction,the Sn/SnO/SnO₂nanosheets,which are prepared by the sequential hydrothermal reaction,calcined crystallization and low-temperature H₂treatment,exhibit a high FEHCOOH of 89.6%at-0.9 VRHE as well as a large cathodic current density.Systematic experimental and theoretical results corroborate that multivalent Sn species synergistically energize the CO₂activation,the HCOO*adsorption,and the electron transfer,which make Sn/SnO/SnO₂favour the conversion from CO₂into HCOOH in both thermodynamics and kinetics.This proof-of-concept study establishes a relationship between the enhanced performance and the multivalent Sn species,and also provides a practicable and scalable avenue for rational engineering high-powered electrocatalysts.     

Application of Electroless Fe-42Ni(P) Film for Under-bump Metallization on Solder Joint

Because Fe has a more negative standard reduction potential than Ni, the simultaneous electroless deposition of Fe and Ni is difficult. In this study, Fe-42Ni(P) electroless deposit was prepared by using disodium ethylene diamine tetraacetate (ETDA-2Na) as complexing agent to reduce the difference in the electrode potential between Ni2+ and Fe2+ . The solderability and the interfacial reaction between Fe-42Ni(P) alloy and Sn were investigated. It was found that the electroless Fe-42Ni(P) alloy has excellent wettability with Sn. Moreover, the interfacial reaction rate between Fe-42Ni(P) and Sn is very slow. These results suggest that Fe-42Ni(P) alloy may become an attractive under-bump metallization (UBM).     

Precipitates and alloying elements distribution in nearαtitanium alloy Ti65

Precipitates,including silicides and Ti3 Al(α2)phase,and alloying elements distribution in a near a titanium alloy Ti65(Ti-5.8 Al-4.0 Sn-3.5 Zr-0.5 Mo-0.3 Nb-1.0 Ta-0.4 Si-0.8 W-0.05 C)after solution treatment and aging process were characterized by using transmission electron microscopy(TEM)and atom probe tomography(APT).Quantitative composition analysis and TEM observation indicate that the silicides fit to(Ti,Zr)6(Sl,Sn)3.Zr exhibits aβ-stabilizing effect in near a titanium alloys but is weaker than otherβstabilizing elements.The enriching tendency of the alloying elements in the retainedβphase is in the order of Zr相似文献   

Highly selective electrocatalytic Cl− oxidation reaction by oxygen-modified cobalt nanoparticles immobilized carbon nanofibers for coupling with brine water remediation and H2 production

Combining the H2 production with brine remediation is regarded as a sustainable approach to achieving clean H2 energy. However, designing stable Cl? oxidation reaction (COR) electrocatalyst is the key to realize this route. Herein, a type of oxygen-modified Co nanoparticles anchored graphitic carbon nanofibers catalyst (Co/GCFs) was synthesized through a two-step strategy of adsorption and pyrolysis. The Co/GCFs-2.4 exhibits high selectivity and stability for COR at neutral electrolyte. It is worth noting that unlike the water oxidation, the chemical valence of cobalt has not changed during the COR. Further results demonstrated that the oxygen-modified Co nanoparticles provide active sites for selective COR, meanwhile, the graphitic carbon gives rise to strong catalytic stability. Thanks to the superior COR and H2 production activity of Co/GCFs-2.4, a two-electrode brine electrocatalysis system employing Co/GCFs-2.4 as both cathode and anode for H2 production exhibited robust stability, efficient and high Faraday efficiency (98%-100%). We propose that this work provides a novel strategy for designing efficient and stable catalysts with electrocatalytic COR and HER activities at neutral brine water for practically coupling with H2 production by water electrolysis and brine water remediation.     

Thermoelectric characteristics of nanocomposites made of HgSe and Ag nanoparticles for flexible thermoelectric devices

We synthesized thermoelectric nanocomposites by mixing HgSe nanoparticles (NPs) and Ag NPs in a solution and investigated the thermoelectric properties of the nanocomposite thin films on flexible plastic substrates.The X-ray diffraction patterns and the X-ray photoelectron spectra of the nanocomposites demonstrate that cation-exchange reactions occurred spontaneously in the mixed solution of HgSe and Ag NPs and that the HgSe NPs were completely converted to Ag2Se when the Ag NP content was 20 vol.％.The maximum power factor and the thermoelectric figure of merit were obtained as 75 FμW/mK2 and 0.043 at 300 K,respectively,when the Ag NP content was 10 vol.％,which is 100 times higher than that of HgSe NP thin films.In addition,the mechanical stability of the thermoelectric nanocomposite film was confirmed through repeated bending tests.     

Defect Engineering on Carbon‑Based Catalysts for Electrocatalytic CO2 Reduction

Electrocatalytic carbon dioxide(CO2)reduction(ECR)has become one of the main methods to close the broken carbon cycle and temporarily store renewable energy,but there are still some problems such as poor stability,low activity,and selectivity.While the most promising strategy to improve ECR activity is to develop electrocatalysts with low cost,high activity,and long-term stability.Recently,defective carbon-based nanomaterials have attracted extensive attention due to the unbalanced electron distribution and electronic structural distortion caused by the defects on the carbon materials.Here,the present review mainly summarizes the latest research progress of the construction of the diverse types of defects(intrinsic carbon defects,heteroatom doping defects,metal atomic sites,and edges detects)for carbon materials in ECR,and unveil the structure-activity relationship and its catalytic mechanism.The current challenges and opportunities faced by high-performance carbon materials in ECR are discussed,as well as possible future solutions.It can be believed that this review can provide some inspiration for the future of development of high-performance ECR catalysts.     

Efficient Two‑Dimensional Perovskite Solar Cells Realized by Incorporation of Ti3C2Tx MXene as Nano‑Dopants

Two-dimensional(2D)perovskites solar cells(PSCs)have attracted considerable attention owing to their excellent stability against humidity;however,some imperfectness of 2D perovskites,such as poor crystallinity,disordered orientation,and inferior charge transport still limit the power conversion efficiency(PCE)of 2D PSCs.In this work,2D Ti3C2Tx MXene nanosheets with high electrical conductivity and mobility were employed as a nanosized additive to prepare 2D Ruddlesden–Popper perovskite films.The PCE of solar cells was increased from 13.69(without additive)to 15.71%after incorporating the Ti₃C₂T_x nanosheets with an optimized concentration.This improved performance is attributed to the enhanced crystallinity,orientation,and passivated trap states in the 3D phase that result in accelerated charge transfer process in vertical direction.More importantly,the unencapsulated cells exhibited excellent stability under ambient conditions with 55±5%relative humidity.     

Ultrathin Co(Ni)-doped MoS<Subscript>2</Subscript> nanosheets as catalytic promoters enabling efficient solar hydrogen production

The design of efficient artificial photosynthetic systems that harvest solar energy to drive the hydrogen evolution reaction via water reduction is of great importance from both the theoretical and practical viewpoints.Integrating appropriate co-catalyst promoters with strong light absorbing materials represents an ideal strategy to enhance the conversion efficiency of solar energy in hydrogen production.Herein,we report,for the first time,the synthesis of a class of unique hybrid structures consisting of ultrathin Co(Ni)-doped MoS2 nanosheets (co-catalyst promoter) intimately grown on semiconductor CdS nanorods (light absorber).The as-synthesized one-dimensional CdS@doped-MoS2 heterostructures exhibited very high photocatalytic activity (with a quantum yield of 17.3％) and stability towards H2 evolution from the photoreduction of water.Theoretical calculations revealed that Ni doping can increase the number of uncoordinated atoms at the edge sites of MoS2 nanosheets to promote electron transfer across the CdS/MoS2 interfaces as well as hydrogen reduction,leading to an efficient H2 evolution reaction.     

Controlled growth and composition of multivariate metal-organic frameworks-199 via a reaction-diffusion process

In this paper,we exploit our prior successful synthesis of MOF-199 single crystals using the reaction-diffusion framework(RDF),to synthesize multivariate metal-organic frameworks(MTV-MOFs)version with enhanced properties.The MTV-MOFs are synthesized by creating defects within the MOF-199 crystal structure by integrating organic linkers entailing different functional groups.Accordingly,5-aminoisophthalic acid(NH₂-BDC)and 5-hydroxyisophthalic acid(OH-BDC)are separately mixed with 1,3,5-benzenetricarboxylic acid(BTC)in three different starting ratios of X-BDC:BTC(1:3,1:1)and(3:1).The effects of this linker on the morphology of the synthesized MTV-MOFs,their thermal stability,and their surface area are investigated.The extent of the incorporation of the linkers in the framework is elucidated via¹H-NMR spectroscopy and it is shown that the incorporation varies as a function of the location along the tubular reactor,a characteristic of RDF.The enhanced properties of the synthesized MTV-MOFs are further demonstrated by measuring its adsorptive capability for methylene blue(MB)and rhodamine B(Rh B)in aqueous solution,and compared with that of the as-synthesized MOF-199.The kinetic and thermodynamic studies reveal that MTV-MOFs with the ratio of X-BDC:BTC(1:1)exhibit the best uptakes of MB(263 mg/g)for X=OH and Rh B(156 mg/g)for X=NH₂.The adsorbents are also easily regenerated for three consecutive cycles without losing their efficiency.We finally demonstrate that MTV-MOFs can be designed to tune the dye removal selectivity and enhance the removal capacity of both MB and RhB in a binary aqueous solution of these dyes.     

SiOx/C-Ag nanosheets derived from Zintl phase CaSi2 via a facile redox reaction for high performance lithium storage

As one of the high-capacity anodes in lithium-ion batteries(LIBs),silicon oxide(SiOx)has attracted wide attention due to its high theoretical capacity,low cost,and proper working voltage.However,the huge volume change and the intrinsic poor conductivity of SiOx still hinder the practical applications.How to address the issues is the focus of current research.In this work,firstly,hydrogen passivated Si nanosheets(Si6H6)were prepared from Zintl phase CaSi2,then,two-dimensional Ag nanoparticle modified SiOVC nanocomposite was prepared via a facile complex redox reaction between SieH6 and AgN03-aniline complexing agent.In this design,aniline was served as carbon sources,and Si6H6could be transformed to SiOx by AgN03 in mild solution condition.The obtained Ag modified SiOVC(SiOx/C-Ag)electrode exhibited high specific capacity(550 mAh·g^-1at 0.6 A·g^-1),superior rate,and cycling performance when served as anode for LIBs.     

A multi-step induced strategy to fabricate core-shell Pt-Ni alloy as symmetric electrocatalysts for overall water splitting

Devising an electrocatalyst with brilliant efficiency and satisfactory durability for hydrogen production is of considerable demand,especially for large-scale application.Herein,we adopt a multi-step consequential induced strategy to construct a bifunctional electrocatalyst for the overall water splitting.Graphene oxide(GO)was used as a carbon matrix and in situ oxygen source,which was supported by the octahedral PtNi alloy to form the PtxNiy-GO precursor.When calcinating in Ar atmosphere,the oxygen in GO induced the surface segregation of Ni from the PtNi octahedron to form a core-shell structure of Ptx@Niy.Then,the surface-enriched Ni continuously induced the reformation of C in reduced graphene oxide(rGO)to enhance the degree of graphitization.This multi-step induction formed a nanocatalyst Pt_x@Ni_y-rGO which has very high catalytic efficiency and stability.By optimizing the feeding ratio of PtNi(Pt:Ni=1:2),the electrolytic overall water splitting at 10 mA·cm^-2 can be driven by an electrolytic voltage of as low as 1.485 V,and hydrogen evolution reaction(HER)only needs an overpotential of 37 mV in 1.0 M KOH aqueous solution.Additionally,the catalyst exhibited consistent existence form in both HER and oxygen evolution reaction(OER),which was verified by switching the anode and cathode of the cell in the electrolysis of water.This work provides a new idea for the synthesis and evaluation of the bifunctional catalysts for water splitting.     

The growth mechanisms of θ’ precipitate phase in an Al-Cu alloy during aging treatment

The plate-shaped θ’(Al2 Cu) precipitate acts as one of the primary strengthening phases in Al-Cu alloys.The interface,especially the semicoherent interface,between Al-Cu solid solution(αAl) and θ’ phase contains a lot of clues about phase transformations.Thus,these interfacial structures in an Al-Cu alloy after high-temperature and longtime aging have been analyzed in detail using atomic-scale high-angle annular dark-field scanning transmission electron microscopy and first-principles calculations in this work.It was found that the lateral growth of θ’ precipitates is subjected to a combination of several major mechanisms under this aging condition.Except for some common intermediate phases,two novel and striking structures were observed on the interface,which implies two alternative atomic diffusion mechanisms for θ’ precipitate growth.For one condition,the atomic diffusion from αAl to θ’ phase transformation adopts an interstitialcy mechanism based on additional Al atoms.For the other condition,the diffusion is carried out through Al atoms.Both mechanisms are distinctly different from the previous theory based on direct diffusion of Cu atoms.The first-principle calculations also confirm that these newfound diffusion processes are ene rgetically favored.