MESO-SUBSTITUTION REACTION OF ZINC OCTAETHYLPORPHYRIN VIA ANODIC OXIDATION

meso-Nitration,chlorination and acetoxylation of ZnOEP via anodic oxidation are reported to proceed via EE'C,ECE and EE'C mechanism respectively.

Numerical Simulation for Crevice Corrosion of 304 Stainless Steel in Sodium Chloride Solution

The authors presented a mechanistic model describing the chemical reactions within a corroded thin, narrow crevice. In the mathematical model, a two-dimensional steady-state was used to predict the crevice pH profile by taking into account dissolved oxygen and hydrogen ions within the crevice. It consists of six parallel electrochemical reactions： multi anodic reactions（Fe, Cr, Ni dissolution reactions） and three cathodic reactions（the oxygen reduction, the hydrogen reaction and water dissociation）. Current density distribution and oxygen concentration distribution were determined to be corresponding to the evolution of potential distribution within the crevice. The contribution of each metal reaction to the overall corrosion process was in proportion to the mole fraction, and the simulation pro vided a good agreement with published experimental results for the crevice corrosion of stainless steel in sodium chloride solution.

Crystal reconstruction of V_(2)O_(3)/carbon heterointerfaces via anodic hydration for ultrafast and reversible Mg-ion battery cathodes

Magnesium-ion batteries(MIBs)have promising applications because of their high theoretical capacity and the natural abundance of magnesium Mg.However,the kinetic performance and cyclic stability of cathode materials are limited by the strong interactions between Mg ions and the crystal lattice.Here,we demonstrate the unique Mg^(2+)-ion storage mechanism of a hierarchical accordion-like vanadium oxide/carbon heterointerface(V_(2)O_(3)@C),where the V_(2)O_(3) crystalline structure is reconstructed into a MgV_(3)O_(7)·H_(2)O phase through an anodic hydration reaction upon first cycle,for the improved kinetic and cyclic performances.As verified by in situ/ex situ spectroscopic and electrochemical analyses,the fast charge transfer kinetics of the V_(2)O_(3)@C cathode were due to the crystal-reconstruction and chemically coupled heterointerface.The V_(2)O_(3)@C demonstrated an ultrahigh rate capacity of 130.4 mAh g^(-1)at 50000 mA g^(-1)and 1000 cycles,achieving a Coulombic efficiency of 99.6%.The high capacity of 381.0 mA h g^(-1)can be attributed to the reversible Mg^(2+)-ion intercalation mechanism observed in the MgV_(3)O_(7)·H_(2)O phase using a 0.3 M Mg(TFSI)2/ACN(H_(2)O)electrolyte.Additionally,within the voltage range of 2.25 V versus Mg/Mg^(2+),the V_(2)O_(3)@C exhibited a capacity of 245.1 mAh g^(-1)when evaluated with magnesium metal in a 0.3 M Mg(TFSI)^(2+)0.25 M MgCl_(2)/DME electrolyte.These research findings have important implications for understanding the relationship between the Mg-ion storage mechanism and reconstructed crystal phase of vanadium oxides as well as the heterointerface reconstruction for the rational design of MIB cathode materials.

Porous CuO nanowires as the anode of rechargeable Na-ion batteries

We report the preparation of porous CuO nanowires that are composed of nanoparticles （-50 nm） via a simple decomposition of a Cu（OH）2 precursor and their application as the anode materials of rechargeable Na-ion batteries. The as-prepared porous CuO nanowires exhibit a Brunauer-Emmett-Teller （BET） surface area of 13.05 m^2.g^-1, which is six times larger than that of bulk CuO （2.16 m^2.g^-1）. The anode of porous CuO nanowires showed discharge capacities of 640 mA.h.g^-1 in the first cycle and 303 mA.h.g^-1 after 50 cycles at 50 mA.g^-1 The high capacity is attributed to porous nanostructure which facilitates fast Na-intercalation kinetics. The mechanism of electrochemical Na-storage based on conversion reactions has been studied through cyclic voltammetry, X-ray diffraction （XRD）, Raman spectroscopy, and high resolution transmission electron microscopy （HRTEM）. It is demonstrated that in the discharge process, Na＋ions first insert into CuO to form a CuⅡ1-x CuⅠ x O1-x/2solid and a Na2O matrix then CuⅡ1-xCu Ⅰ xO1-x/2 reacts with Na＋ to produce Cu2O, and finally Cu2O decompose into Cu nanoparticles enclosed in a Na2O matrix. During the charge process, Cu nanopartides are first oxidized to generate Cu2O and then converted back to CuO. This result contributes to the design and mechanistic analysis of high-performance anodes for rechargeable Na-ion batteries.

EQCM for In-depth Study of Metal Anodes for Electrochemical Energy Storage

Electrochemical quartz crystal microbalance(EQCM)is a powerful tool to study the mass change and charge transfer during electrochemical process.The mass change on the electrode surface can be monitored with high precision and high sensitivity,making it possible to analyze the in-depth mechanism of electrode reactions.The application of metal anodes has exhibited great potential for the future energy storage devices for the elevated capacity.Herein,we review the research progress utilizing EQCM for metal anodes,including the deposition/dissolution process,the side reactions,the effect of additives,etc.Furthermore,we also put forward a perspective on research of the mechanism and performance improvement of metal anodes.

Mn3O4/carbon nanotube nanocomposites recycled from waste alkaline Zn–MnO2 batteries as high-performance energy materials

Alkaline zinc manganese dioxide（Zn–MnO2）batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO2 batteries has always been a hot environmental concern. In this study, a simple and costeffective process for synthesizing Mn3O4/carbon nanotube（CNT） nanocomposites from recycled alkaline Zn–MnO2 batteries is presented. Manganese oxide was recovered from spent Zn–MnO2 battery cathodes. The Mn3O4/CNT nanocomposites were produced by ball milling the recovered manganese oxide in a commercial multi-wall carbon nanotubes（MWCNTs） solution. Scanning electron microscopy（SEM） analysis demonstrates that the nanocomposite has a unique three-dimensional（3D） bird nest structure. Mn3O4 nanoparticles are homogeneously distributed on MWCNT framework. Mn3O4/CNT nanocomposites were evaluated as an anode material for lithium-ion batteries, exhibiting a highly reversible specific capacitance of -580 mA h·g^-1 after 100 cycles. Moreover, Mn3O4/CNT nanocomposite also shows a fairly positive onset potential of -0.15 V and quite high oxygen reducibility when considered as an electrocatalyst for oxygen reduction reaction.

Recent progress in cobalt-based compounds as high-performance anode materials for lithium ion batteries

Despite carbonaceous materials are widely employed as commercial negative electrodes for lithium ion battery, an urge requirement for new electrode materials that meet the needs of high energy density, long cycle life, low cost and safety is still underway. A number of cobalt-based compounds（Co（OH）_2, Co_3O_4, CoN, CoS,CoP, NiCo_2O_4, etc.） have been developed over the past years as promising anode materials for lithium ion batteries（LIBs） due to their high theoretical capacity, rich redox reaction and adequate cyclability. The LIBs performances of the cobalt-based compounds have been significantly improved in recent years, and it is anticipated that these materials will become a tangible reality for practical applications in the near future. However, the different types of cobalt-based compounds will result in diverse electrochemical performance. This review briefly analyzes recent progress in this field, especially highlights the synthetic approaches and the prepared nanostructures of the diverse cobalt-based compounds and their corresponding performances in LIBs, including the storage capacity, rate capability, cycling stability and so on.