Decouple charge transfer reactions in the Li-ion battery

In the development of Li-ion batteries(LIBs)with high energy/power density,long cycle-life,fast charging,and high safety,an insight into charge transfer reactions is required.Although electrochemical impedance spectroscopy(EIS)is regarded as a powerful diagnosis tool,it is not a direct but an indirect measurement.With respect to this,some critical questions need to be answered:(i)why EIS can reflect the kinetics of charge transfer reactions;(ii)what the inherent logical relationship between impedance models under different physical scenes is;(iii)how charge transfer reactions compete with each other at multiple scales.This work aims at answering these questions via developing a theory framework so as to mitigate the blindness and uncertainty in unveiling charge transfer reactions in LIBs.To systematically answer the above questions,this article is organized into a three-in-one(review,tutorial,and research)type and the following contributions are made:(i)a brief review is given for impedance model development of the LIBs over the past half century;(ii)an open source code toolbox is developed based on the unified impedance model;(iii)the competive mechanisms of charge transfer reactions are unveiled based on the developed EIS-Toolbox@LIB.This work not only clarifies theoretical fundamentals,but also provides an easy-to-use open source code for EIS-Toolbox@LIB to optimize fast charge/discharge,mitigate cycle aging,and improve energy/power density.

Reversed charge transfer induced by nickel in Fe-Ni/Mo_(2)C@nitrogen-doped carbon nanobox for promoted reversible oxygen electrocatalysis

The interaction between metal and support is critical in oxygen catalysis as it governs the charge transfer between these two entities,influences the electronic structures of the supported metal,affects the adsorption energies of reaction intermediates,and ultimately impacts the catalytic performance.In this study,we discovered a unique charge transfer reversal phenomenon in a metal/carbon nanohybrid system.Specifically,electrons were transferred from the metal-based species to N-doped carbon,while the carbon support reciprocally donated electrons to the metal domain upon the introduction of nickel.This led to the exceptional electrocatalytic performances of the resulting Ni-Fe/Mo_(2)C@nitrogen-doped carbon catalyst,with a half-wave potential of 0.91 V towards oxygen reduction reaction(ORR)and a low overpotential of 290 m V at 10 mA cm^(-2)towards oxygen evolution reaction(OER)under alkaline conditions.Additionally,the Fe-Ni/Mo_(2)C@carbon heterojunction catalyst demonstrated high specific capacity(794 mA h g_(Zn)~(-1))and excellent cycling stability(200 h)in a Zn-air battery.Theoretical calculations revealed that Mo_(2)C effectively inhibited charge transfer from Fe to the support,while secondary doping of Ni induced a charge transfer reversal,resulting in electron accumulation in the Fe-Ni alloy region.This local electronic structure modulation significantly reduced energy barriers in the oxygen catalysis process,enhancing the catalytic efficiency of both ORR and OER.Consequently,our findings underscore the potential of manipulating charge transfer reversal between the metal and support as a promising strategy for developing highly-active and durable bi-functional oxygen electrodes.

Regulating the interfacial charge transfer and constructing symmetry-breaking sites for the enhanced N_(2) electroreduction activity

The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,while the challenge associated with N_(2) activation highlights the demand for efficient electrocatalysts.Herein,we demonstrate that PdCu nanoparticles with different Pd/Cu ratios anchored on boron nanosheet(PdCu/B)behave as efficient NRR electrocatalysts toward NH_(3) synthesis.Theoretical and experimental results confirm that the highly efficient NH_(3) synthesis can be achieved by regulating the charge transfer between interfaces and forming a symmetry-breaking site,which not only alleviates the hydrogen evolution but also changes the adsorption configuration of N_(2) and thus optimizes the reaction pathway of NRR over the separated Pd sites.Compared with monometallic Pd/B and Cu/B,the PdCu/B with the optimized Pd/Cu ratio of 1 exhibits superior activity and selectivity for NH_(3) synthesis.This study provides new insight into developing efficient catalysts for small energy molecule catalytic conversion via regulating the charge transfer between interfaces and constructing symmetry-breaking sites.

Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4＋ charge transfer transition

Ce^4＋-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4＋ ions doped in Ca2SnO4 occupy the Sn^4＋ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime （-83μs） for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4＋ charge transfer （CT）. The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4＋ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration （x - 0.03） is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%.

PHOTOINDUCED CHARGE TRANSFER REACTION OF BENZOPHENONE WITH AMINE IN VESICLES

Photoinduced charge transfer reaction of benzophenone(BP) with, mine was carried out in the vesicles of dicetyldimethylammonium bromide (DCDAB) over wide ranges of amine concentration (0. 01～4. 0M). Linear plots of φ^(-1) vs. [TEA]^(-1) at low concentration of amine (<0.02M) and Φ^(-1) vs. [TEA]^(-2) at high concentration were obtained. Kinetic data demonstrate that the electron transfer is promoted significantly by DCDAB vesicles and proton transfer becomes more efficient at high Rmlne concentrations, leading to a decrease of Kd/Kr and increase of Kh/Ke. The kinetic expressions of photoreaction of BP bound to DCDAB bilayer are developed.

Non-Adiabatic Molecular Dynamics Simulations of Non-Charge-Transfer and Charge-Transfer Scattering in H^++CO2 at ELab=30 eV

The H^++CO2 reaction at high energies is relevant in atmospheric chemistry,astrophysics,and proton cancer therapy research.Therefore,we present herein a complete investigation of H^++CO2 at ELab=30 eV with the simplest-level electron nuclear dynamics(SLEND)method.SLEND describes nuclei via classical mechanics and electrons with a singledeterminantal Thouless wavefunction.The 3402 SLEND conducted simulations from 42 independent CO2 target orientations provide a full description of all the reactive processes and their mechanisms in this system:non-charge-transfer scattering(NCTS),charge-transfer scattering(CTS),and single C=O bond dissociation;all this valuable information about reactivity is not accessible experimentally.Numerous details of the projectile scattering patterns are provided,including the appearance and coalescence of primary and secondary rainbow angles as a function of the target orientation.SLEND NCTS and CTS differential cross sections(DCSs)are evaluated in conjunction with advanced semi-classical techniques.SLEND NCTS DCS agrees well with its experimental counterpart at all the measured scattering angles,whereas SLEND CTS DCS agrees well at high scattering angles but less satisfactorily at lower ones.Remarkably,both NCTS and CTS SLEND DCSs predict the primary rainbow angle signatures in agreement with the experiment.

Charge Transfer Properties in MEH-PPV/PS:MWCNTs Nanocomposites

The effect of composition and annealing temperature on charge transfer properties, in a donor/acceptor nanocomposites based on poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) and MWCNTs functionalized with Polystyrene (PS:MWCNTs), have been investigated. The quenching of photoluminescence (PL) intensity of pure MEH-PPV, by adding different amounts of functionalized carbon nanotubes, exhibits that a photoinduced charge transfer has been occurred. Charge transfer efficiency was obtained for an acceptable concentration of PS:MWCNTs about 0.5 wt% and at annealed temperature of about 80℃. Quenching efficiency studies imply that MEH-PPV/PS:MWCNTs nanocomposites reveal a high degree of PL quenching, reaching a value of η = 76.9%.

Theoretical Study of the Isomerization Reaction of 1-3 H Transfer on Formamidine Substituted by Halogen

The ab initio method has been used to study the 1-3 H transfer reaction on formamidine substituted by halogen. The calculation results show that the substituted halogen has two effects on the 1-3 H transfer reaction: decreasing the activation energy and stabilizing the C=N double bond owing to the conjugative effect of p-π-p of products and transition states.

Incoherent Oscillations Accompanying Charge Separation in Photosynthetic Reaction Centers

Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coordinates leading to oscillations in the kinetics is examined. Different schemes of charge separation are investigated. A good fitting of experimental kinetics of native Rba. sphaeroides RCs is achieved in the five states model P*1BAHA&harr;P*2BAHA&harr;I&harr;P+HA&harr;P+BA with two excited states BAHA and BAHA and three charge separated states I, P+HA and P+BA (P is a primary electron donor, bacteriochlorophyll dimer, BA and HA are an electron acceptor, monomeric bacteriochlorophyll and bacteriopheophytin in active A-branch, respectively). In the model only the first excited state is directly populated by optical excitation. The emission of the two excited states is assumed to be at 905 and 940 nm, respectively. The intermediate state I is assumed to absorb at 1020 nm as well as the P+HA state. The model explains the deep oscillations in the kinetics of the stimulated emission and of the absorption. In the simpler schemes without the I state or with only one excited state the accordance with the experiment is achieved at unreal parameter values. A possible nature of the I and BAHA states and a possible incoherent nature of the oscillations are discussed.

Enhanced oxygen reduction reaction performance over Pd catalysts by oxygen-surface-modified SiC

Obtaining a detailed understanding of the surface modification of supports is crucial;however,it is a challenging task for the development and large-scale fabrication of supported electrocatalysts that can be used as alternatives to Pt-based catalysts for the oxygen reduction reaction(ORR).In this study,commercial silicon carbide(SiC)was modified through surface oxidization(O-SiC)to support the use of Pd nanoparticles(Pd NPs)as electrocatalysts for ORR.The obtained Pd/O-SiC catalysts exhibited better ORR activity,stronger durability,and higher resistance to methanol poisoning than that exhibited by commercial Pt/C.The role of the support in enhancing the ORR performance,especially the oxidization of SiC surfaces,was discussed in detail based on the experimental characterizations and density functional theory calculations.The underlying mechanism of the superior ORR performance of Pd/O-SiC catalysts was attributed to the charge transfer from SiC_(x)O_(y)to Pd NPs on the surfaces of SiC and the strong metal–support interactions(SMSIs)between Pd and SiC_(x)O_(y).The charge transfer enhanced the ORR activity by inducing electron-rich Pd,increased the adsorption of the key intermediate OOH,and decreased the Gibbs free energy of the critical ORR step.Furthermore,SMSIs enhanced the ORR stability of the Pd/O-SiC catalyst.This study provided a facile route for designing and developing highly active Pd-based ORR electrocatalysts.

Hierarchical monolithic carbon with high transfer performance for hydrogen evolution reaction

Electrocatalysis is an efficient green process for energy conversion.However,for gas-related electrocatalytic reaction,sluggish gas transport has inhibited significantly the promotion of electrocatalytic performances.Herein,hierarchical monolithic material 3 DPC-650 and 3 DPC-650@Ni/Ni(OH)_(2) were prepared by3 D printing polyethyleneimine cross-linking oxygenated carbon nanotube and following nickel electrodeposition.3 DPC-650 and 3 DPC-650@Ni/Ni(OH)_(2) have regular pore structure in consistence with3 D printing design and uniform dispersed elements.Amide bonds and carbon defects are presented on the surface of 3 DPC-650 and 3 DPC-650@Ni/Ni(OH)_(2) as well as uniformly distributed β-Ni(OH)_(2) on3 DPC-650@Ni/Ni(OH)_(2).3 DPC-650 and 3 DPC-650@Ni/Ni(OH)_(2) present lower overpotentials of 322 and160 mV for hydrogen evolution reaction in 1.0 M KOH at 50 mA cm^(-2),respectively.The ordered channel,high turnover frequency and electrochemically active surface area,hydrophilic and aerophobic properties result in the higher performance of 3 DPC-650 and 3 DPC-650@Ni/Ni(OH)_(2) than traditional supports(carbon paper,carbon cloth,and nickel foam) and electrocatalysts.This work provides an efficient pathway for design and preparation of the monolithic electrocatalyst and electrode used for electrochemical reactions where gas is involved.

2,4-二硝基酚荷移分光光度法测定阿奇霉素

目的:建立用荷移分光光度法测定阿奇霉素含量的方法。方法:利用阿奇霉素与2,4-二硝基酚在乙醇中发生荷移反应生成1:2型络合物,在364 nm波长处测定阿奇霉素的吸收度。结果:药物浓度在5—30μg·mL^(-1)范围内线性关系良好,回归方程为A=34.6C-1.76×10^(-2),相关系数0.9995,平均回收率99.3%,RSD<0.39%。结论:方法简便、灵敏、准确,可作为阿奇霉素制剂的含量测定方法。

马来酸氯本那敏与7,7,8,8-四氰基对二次甲基苯醌的荷移反应

以马来酸氯本那敏 (商品名扑尔敏 )作为电荷给体 ,7,7,8,8 四氰基对二次甲基苯醌 (TCNQ)作为电子受体 ,研究了它们之间形成电荷转移络合物的最佳条件。结果表明 :在丙酮介质中 ,二者于室温 (2 0℃ )下 30min即可形成 1∶2络合物 ,室温下至少稳定 2h。络合物的最大吸收波长为 84 5nm。表观摩尔吸光系数ε为4 6 3× 10 4L·mol-1·cm-1,在 0～ 6mg/L范围内符合比尔定律。方法的相对标准偏差为 1.2 % (n =10 )。对形成荷移络合物的机理进行了探讨 ;用拟定的方法对片剂样品中马来酸氯本那敏的含量进行了测定 ,结果与药典方法一致 。

荷移反应-紫外分光光度法测定尿酸

本文采用紫外分光光度法研究了尿酸与四氰乙烯之间的荷移反应。尿酸与四氰乙烯可以形成淡绿色的荷移配合物。其配合比为1：2。在测定波长395nm处，该配合物的表观摩尔吸光系数ε=6．24×10^4L·mol^-1·cm^-1，方法线性范围为5．7×10^-7～5．7×10^-6mol·L^-1。应用本法测定了人体代谢物中尿酸的合量，回收率为96．4％～110．5％，相对标准偏差（RSD）为1．98％（n=7）。

结晶紫-红霉素体系电荷转移分光光度法测定红霉素的研究

目的:建立用结品紫电荷转移分光光度法测定红霉素的新方法。方法:以二次石英蒸馏水为溶剂,红霉素与结晶紫在60℃水浴中进行电荷转移反应生成1:1稳定的配合物,用紫外分光光度计于最大吸收波长593 nm 处测定其吸光度。结果:此法灵敏度高(ε=3.07×10~4 L·mol^(-1)·cm^(-1)),精密度较好(对25 mL 5.0×10^(-3)mg·mL^(-1)红霉素测定9次,RSD=2.9%)。红霉素的浓度在0～0.022 mg·mL^(-1)范围内服从 Beer 定律,方法的检出限为2.10μg·mL^(-1)。本法探讨了反应机理,其中红霉素作为电子给予体、结晶紫作为电子接受体发生了荷移反应。结论:本方法可靠,重现性好,可用于红霉素肠溶片和兽用红霉素含量的测定。

有机-无机杂化纳米材料的制备、表征及性质

利用低温固相反应首次制备了 [(CH3 ) 4 N] 3 PW12 O4 0 ·6H2 O(Ⅰ ) ,[(CH3 ) 4 N] 6P2 Mo18O62 ·9H2 O(Ⅱ ) ,[HMTAH2 ] 2 ·SiW12 O4 0 ·7H2 O(Ⅲ )等纳米粒子 ,并用红外光谱、透射电镜、X射线粉末衍射等手段进行表征 .结果表明 ,粒子大小均一 ,平均粒子直径为 4～ 8nm ,并具有潜在的电荷转移盐性质及非线性光学性质 .

头孢米诺钠与2,4-二硝基苯酚的荷移反应及其测定

目的建立用荷移分光光度法测定头孢米诺钠含量的方法。方法利用头孢米诺钠与2，4-二硝基苯酚在甲醇一丙酮介质中反应，形成电荷转移络合物，采用分光光度法测定。结果荷移络合物在403nm处有最大吸收，表观摩尔吸光系数为ε=1．47×10^4L／（mol·cm），药物浓度在4～40μg／ml范围内符合比耳定律线性关系，方法平均回收率大于97．0％。结论荷移分光光度法简便、准确、灵敏，可作为头孢米诺钠制剂的含量测定方法。

阿奇霉素的7,7,8,8-四氰基对二次甲基苯醌荷移配合物生成光度法分析

A spectrophotometric method for the determination of azithromycin has been developed based on the charge transfer reaction.The reaction between azithromycin and 7,7,8,8-tetracyanoquinodemethane（（TCNQ）） was completed in acetone medium in 30 minutes at 50 ℃.Beer′s law is obeyed in the range of（12.1）867.6 mg/L for the determination of azithromycin.The molar absorptivity of the complex at 745 nm is 1.44×103 L/（mol·cm）.The relative standard deviation is 0.96%（n=10）.The composition ratio of the charge transfer complex was found to be 1∶[KG-*3/5]1 by means of the slope ratio and Job′s methods.This method has been applied to the determination of azithromycin in tablets with satisfactory results compared with the Pharmacopoeia method.Recovery was 100.5%.

荷移反应-离心光度法测定盐酸环丙沙星的研究

在水溶液中盐酸环丙沙星与荧光桃红形成荷移络合物。离心分离后，将络合物溶于乙醇溶液中进行光度测定，络合物的最大吸收波长为５４６ｎｍ，盐酸环丙沙星的量浓度在０．５～６×１０－５ｍｏｌ／Ｌ符合比尔定律，ε＝２．７１×１０４。测定了片剂中盐酸环丙沙星的含量。

琥乙红霉素与7,7,8,8-四氰基对二次甲基苯醌的荷移反应

目的:测定琥乙红霉素片剂中琥乙红霉素的含量,增加质量控制和保证手段。方法:利用琥乙红霉素与7,7,8,8-四氰基对二次甲基苯醌(TCNQ)形成1:1荷移络合物,应用分光光度法测定片剂中琥乙红霉素含量。结果:络合物的最大吸收波长是845nm,表观摩尔吸光系数ε为6.01×10~3L·mol^(-1)·cm^(-1),琥乙红霉素在25.86～689.7mg·L^(-1)范围内符合比尔定律,方法的相对标准偏差为0.83%(n=10)。对形成荷移络合物的机理进行了探讨,平均回收率为101%(RSD<1%)。结论:方法简单、灵敏、准确,可作为该药的含量测定方法。