Hydrothermal Synthesis, Crystal Structure, Spectrum and Electrochemical Analysis of the Copper(Ⅱ) Coordination Polymer

The three-dimensional framework copper（Ⅱ） coordination polymer with basic copper carbonate and 3-（pyridin-2-yl）-1,2,4-triazole has been hydrothermally synthesized. It crystallizes in monoclinic space group P21/c, with a = 1.20860（3）, b = 1.29581（2）, c = 1.67863（3） nm, β = 116.0280（2）°, C21H12Cu3N12, Mr = 623.05, V = 2.36230（9） nm3, Dc = 1.752 g/cm3, Z = 4, F（000） = 1236, GOOF = 1.037, the final R = 0.0408 and wR = 0.1141. Every unit cell contains three copper atoms and three 3-（pyridin-2-yl）-1,2,4-triazole ligands. Every central Cu（Ⅱ） ion is coordinated by four nitrogen atoms of the 3-（pyridin-2-yl）-1,2,4-triazole ligands, forming a distorted tetrahedron. The title complex exhibits an intense photoluminescence at room temperature with the maximum emission at 392 nm. The cyclic voltametric behavior of the complex shows that the electron transfer in electrolysis reaction is irreversible.

Fuel Cell Research Based on Electrochemical Analysis

With the development of social economy and the improvement of people’s living level,the global energy demand is rising rapidly.The reserves of traditional fossil energy such as coal,oil and natural gas are limited,and its depletion is inevitable.And the massive use of fossil energy will also bring a series of environmental problems such as greenhouse effect.Therefore,it is urgent to find a clean and renewable energy.Fuel cell(FC)is a new energy technology that has attracted much attention.It is a power generation system that converts the chemical energy of fossil fuel(coal,oil,natural gas,etc.),biomass fuel or other hydrocarbon fuel(ethanol,propane,butane,etc.)into electrical energy directly without combustion through electrochemical reaction.In the process of fuel cell operation,fuel and air react in different chambers respectively,breaking away from the restriction of Carnot cycle.In this way,the utilization rate of fuel has been greatly improved.Moreover,the fuel cell will only produce H2O,CO2 and other products in the working process,and will not produce dust or other harmful gases.Therefore,the research and development of efficient and clean new energy technology is of great significance to promote the rational use of coal resources and biomass fuel and coordinate the harmonious development of environment and economy.

Modern applications of scanning electrochemical microscopy in the analysis of electrocatalytic surface reactions

Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy,such as those involved in water splitting and artificial photosynthesis,owing to its energy efficiency,simple fabrication,and ease of operation.In this view,it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest,and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations.In this review,we introduce several key methods of scanning electrochemical microscopy(SECM)in its applications towards electrocatalysis.A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism.New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced,and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.

Electrochemical and analytical characterization of three corrosion inhibitors of steel in simulated concrete pore solutions

Corrosion inhibitors for steel, such as sodium phosphate （Na3PO4）, sodium nitrite （NaNO2）, and benzotriazole （BTA）, in simulated concrete pore solutions （saturated Ca（OH）2） were investigated. Corrosion behaviors of steel in different solutions were studied by means of corrosion potential （Ecorr）, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, and potentiodynamic polarization （PDP）. A field emission scanning electron microscope （FESEM） equipped with energy dispersive X-ray analysis （EDXA） was used for observing the microstructures and morphology of corrosion products of steel. The results indicate that, compared with the commonly used nitrite-based inhibitors, Na3PO4 is not a good inhibitor, while BTA may be a potentially effective inhibitor to prevent steel from corrosion in simulated concrete pore solutions.

Emerging wearable flexible sensors for sweat analysis

Sweat,as a biofluid with the potential for noninvasive collection,provides profound insights into human health conditions,because it contains various chemicals and information to be utilized for the monitoring of well-being,stress levels,exercise,and nutrition.Recently,wearable sweat sensors have been developed as a promising substitute to conventional laboratory sweat detection methods.Such sensors are promising to realize low-cost,real-time,in situ sweat measurements,and provide great opportunities for health status evaluation analysis based on personalized big data.This review first presents an overview of wearable sweat sensors from the perspective of basic components,including materials and structures for specific sensing applications and modalities.Current strategies and specific methods of the fabrication of wearable power management are also summarized.Finally,current challenges and future directions of wearable sweat sensors are discussed.

Electrochemical properties of some cobalt antimonides as anode materi-als for lithium- ion batteries

Some cobalt antimonides have been prepared and studied as the candidate anodematerials for lithium ion batteries. Reversible capacities of 424,423 and 546 mA.h.g^(-1) weremeasured at the first cycle for as-solidified CoSb_2, CoSb_3 and annealed CoSb_3 respectively. A lowlithium ions diffusion coefficient in the order of 10^(16) m^2.s^(-1) was estimated from thecoulometric titration measurements in the annealed CoSb_3 electrode. It was found that theelectrochemical properties of fine powders are significantly better than coarse powders. However theSEM picture shows that the nano-sized CoSb_3 powders gathered to larger granules, which worsenssomewhat the capacity retention of the nano-sized materials, although the volume capacities of theannealed and ball milled CoSb_3 remain near twice of that of graphite after 50 cycles.

Electrochemical Performance of Starch-Polyaniline Nanocomposites Synthesized By Sonochemical Process Intensification

The present study deals with the intensified synthesis of starch-polyaniline(starch-PANI)nanocomposite using an ultrasound-assisted method.Starch is a key component in this nanocomposite,which acts as a backbone of the nucleation of PANI.The Electrochemical property of the nanocomposite arises due to the addition of PANI.This is one of green approach for the synthesis of bio nanocomposite using ultrasound.The crystallinity of the composite is evaluated using the Scherrer Formula.The starch-PANI nanocomposite was characterized by XRD,FT-IR,Raman,XPS and TEM.The composite nanoparticles show spherical morphology.The elemental composition of starch-PANI showed O 1s peak at 546 eV,N 1s peak at 416 eV,C 1s peak at 286 eV and S 1s peak at 176 eV.The electrochemical studies of the starch-PANI electrodes are evaluated by cyclic voltammetry(CV),galvanostatic charge/discharge(GCD),and electrochemical impedance spectroscopy(EIS).Starch-PANI electrode has shown the maximum specific capacitance of 499.5 F/g at 5 mV/s scan rate.

Synthesis, Crystal Structure and Electrochemical Properties of a One-dimensional Chain Coordination Polymer [Cu(phen)(2,4,6-TMBA)_2(H_2O)]_n

A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.0293（3）, b = 2.0293（3）, c = 1.3758（2） nm, α =β= γ = 90°, V= 5.6657（13） nm3, Dc= 1.379 g/cm3, Z = 8, μ（MoKa） = 0.815 mm-1, Mr = 588.14, F（000） = 2456, S = 1.047, R = 0.0459 and wR = 0.1053. The crystal structure shows that two neighboring Cu（Ⅱ） ions are linked together by one bridging-chelating 2,4,6-trimethyl-benzoic group, forming a one-dimensional chain structure. Each Cu（Ⅱ） ion is coordinated with two nitrogen atoms from one 1,10-phenanthroline molecule, three oxygen atoms from three 2,4,6-trimethyl-benzoic acid molecules and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. The cyclic voltammetry behavior of the complex was also investigated.

Synthesis, Crystal Structure and Electrochemical Properties of a One-dimensional Chain Coordination Polymer [Mn(NAA)_2(4,4’-bipy)(H_2O)_4]_n

A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this complex： monoclinic, space group P21/c, a = 1.1421（2）, b = 1.6337（3）, c = 0.94177（19） nm, β = 112.15（3）°, V = 1.6275（6） nm^3, De = 1.407 g/cm^3, Z = 2, μ（MoKa） = 0.467 mm^-1, F（000） = 722, S = 1.007, R= 0.0412 and wR = 0.1022. The crystal structure shows that two neighboring manganese（Ⅱ） ions are linked together by one 4,4′-bipy molecule, and the whole complex molecule forms a one-dimensional chain structure. Each manganese（Ⅱ） ion is coordinated with two oxygen atoms of two a-naphthaleneacetic acid molecules, two nitrogen atoms of two 4,4′-bipy molecules and two oxygen atoms from two water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were also analyzed.

Synthesis,Crystal Structure and Electrochemical Properties of a Cadmium(Ⅱ) Complex with α-Furoic Acid and 1,10-Phenanthroline

A new cadmium complex [Cd（phen）3]·（ClO4）2·（α-FRA）-（H2O）3 was prepared by self-assembly of α-furoic acid, 1,10-phenanthroline （phen）, and cadmium perchlorate. It crystallizes in the monoclinic system, space group P21/n, with a = 1.28130（15）, b = 2.5957（3）, c = 1.35449（16） nm, β = 109.395（2）°, V = 4.2492（9） nm^3, Dc = 1.491 g/cm^3, Z = 4, F（000） = 1926, GOOF = 1.023, the final R = 0.0729 and wR = 0.2086. The crystal structure analysis indicates that the cadmium ion is coordinated with six nitrogen atoms from six 1,10-phenanthroline molecules, giving a distorted octahedral coordination geometry. The cyclic voltametric behavior of the complex was also investigated.

Hydrothermal Synthesis,Crystal Structure and Electrochemical Properties of Complex [Cd(phen)_3]·(ClO_4)_2·(p-MBA)_2·(H_2O)_2

One new cadmium complex [Cd（phen）3]·（ClO4）2·（p-MBA）2·（H2O）2 has been hydrothermally synthesized by reacting p-methylbenzoic acid （p-MBA）, 1,10-phenanthroline （phen） and cadmium perchlorate. It crystallizes in the triclinic system, space group P1, with a = 1.2809（3）, b = 1.3431（3）, c = 1.3734（3） nm, α = 84.259（4）, β = 71.603（3）, γ = 74.424（3）°, V= 2.1594（8） nm3, Do = 1.532 g/cm3, Z = 2, F（000） = 1008, μ= 0.697 mm^-1, R = 0.0646 and wR = 0.1648. The crystal structure shows that the cadmium ion is coordinated with six nitrogen atoms from three 1,10-phenanthroline molecules, forming a distorted octahedral coordination geometry. The result of electrochemical property analysis shows that the electron transfer in the electrode reaction is irreversible.

Influence of TiO_2 on the electrochemical performance of pasted typeβ-nickel hydroxide electrode in alkaline electrolyte

Nickel hydroxide was used as the positive electrode material in rechargeable alkaline batteries, which plays a significant role in the field of electric energy storage devices. β-nickel hydroxide（β-Ni（OH）2 ） was prepared from nickel sulphate solution using potassium hydroxide as a precipitating agent. Pure β-phase of nickel hydroxide was confirmed from XRD and FT-IR studies. The effects of TiO2 additive on the β-Ni（OH）2 electrode performance are examined. The structure and property of the TiO2 added β-Ni（OH）2 were characterized by XRD, TG-DTA and SEM analysis. A pasted–type electrode is prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry and electrochemical impedance spectroscopy studies were performed to evaluate the electrochemical performance of the β-Ni（OH）2 and TiO2 added β-Ni（OH）2 electrodes in 6 M KOH electrolyte. Anodic（Epa） and cathodic（Epc）peak potentials are found to decrease after the addition of TiO 2 into β-Ni（OH）2 electrode material. Further,addition of TiO2 is found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. Compared with pure β-Ni（OH）2 lectrode,TiO2 added β-Ni（OH）2 electrode is found to exhibit higher proton diffusion coefficient（D） and lower charge transfer resistance. These findings suggest that the TiO2 added β-Ni（OH）2 electrode possess improved electrochemical properties and thus can be recognized as a promising candidate for the battery electrode applications.

Recovery and separation of Fe and Mn from simulated chlorinated vanadium slag by molten salt electrolysis

Tailings from the vanadium extraction process are discarded each year as waste,which contain approximately 30 wt%of Fe.In our previous work,we extracted Fe and Mn from vanadium slag,and Fe and Mn existed in the form of FeCl_(2) and MnCl_(2) after chlorination by NH_(4) Cl to achieve effective and green usage of waste containing Fe and Mn.In this work,square wave voltammetry(SWV)and cyclic voltammetry(CV)were applied to investigate the electrochemical behaviors of Fe^(2+)and Mn^(2+)in Na Cl-KCl melt at 800℃.The reduction processes of Fe^(2+)and Mn^(2+)were found to involve one step.The diffusion coefficients of FeCl_(2) and Mn Cl_(2) in molten salt of eutectic mixtures Na Cl-KCl molten salt were measured.The electrodeposition of Fe and Mn were performed using two electrodes at a constant cell voltage.The Mn/Fe mass ratio of the electrodeposited product in Na Cl-KCl-2.13 wt%FeCl_(2)-1.07 wt%Mn Cl_(2) was 0.0625 at 2.3 V.After the electrolysis of NaCl-KCl-2.13 wt%Fe Cl_(2)-1.07 wt%MnCl_(2) melted at 2.3 V,the electrolysis was again started under 3.0 V and the Mn/Fe mass ratio of the electrodeposited product was 36.4.This process provides a novel method to effectively separate Fe and Mn from simulated chlorinated vanadium slag.

CoSb_3-graphite composite anode material for lithium ion batteries

The CoSb_3-graphite composite was prepared by ball-milling. Theelectrochemical performance of the composite material was evaluated using the lithium ion model cellLi / LiPF_6 (EC + DMC) / CoSb_3C_4. It was found that the CoSb_3C_4 composite shows higherreversible capacity than the pure CoSb_3 alloy, and its first reversible (Li-ions removal) capacityreaches 721 mA centre dot h centre dot g^(-1), which exceeds the theoretical capacity (550 mA centredot h centre dot g^(-1)) of CoSb_3C_4.

Almond gum assisted synthesis of Mg doped Fe_(2)O_(3) NPs:Structural analysis,electrochemical sensing,and optical applications

Mg-doped Fe_(2)O_(3)nanoparticles(M-FNPs)are successfully prepared first time by facile green-aided(almond gum)combustion route.The structural analysis of synthesized nanoparticles was well analyzed by Powder X-ray Diffrac-tion(PXRD),Fourier Transform Infrared spectroscopy(FT-IR),Scanning Electron Microscope(SEM),Raman spec-troscopy and UV-Visible spectral studies.PXRD showed a nanocrystalline nature and determined the average particle size to be 85 nm.The surface morphologies of the prepared nanocomposite was measured by SEM tech-nique reveals the porous and spongy like structure.The photodegradation activity on 20×10^(−6)of Fast Orange Red(FOR)organic model dye using M-FNPs(50 mg)under UV light irradiation was investigatedin detail.Elec-trochemical examination of the prepared material was conducted using graphite-M-FNP electrode paste in 0.1 M KCl solution,and its performance in redox reaction was determined to be very good via cyclic voltammetry and electrochemical impedance spectroscopy.Further,an extension to sensor studies revealed broad differences in redox positions for paracetamol sensors,at 0.64 V and 0.41 V,confirming highly chemical sensor activity in alkaline medium for 1∼5 mM concentrations.

Colorimetric and electrochemical detection of ligase through ligation reaction-induced streptavidin assembly

We propose a concept for ligase detection by conversion of aggregation-based homogeneous analysis into surface-tethered electrochemical assay through streptavidin(SA)-biotin interaction.Sortase A(Srt A)served as the model analyte and two biotinylated peptides(bio-LPETGG and GGGK-bio)were used as the substrates.Srt A-catalyzed ligation of the peptide substrates led to the generation of bio-LPETGGGKbio.The ligation product(bio-LPETGGGK-bio)induced the aggregation and color change of SA-modified gold nanoparticles(Au NPs)through the SA-biotin interactions,which could be assayed by the colorimetric method.Furthermore,we found that the bio-LPETGGGK-bio could trigger the assembly of tetrameric SA proteins with the formation of the(SA-bio-LPETGGGK-bio)nassemblies through the same interactions.The above results were further confirmed by atomic force microscopy and fluorescent imaging.The insulated assemblies were in-situ fabricated at the SA-modified gold electrode,thus hindering the electron transfer of[Fe(CN)_(6)]^(3-/4-) and leading to an increase in the electron-transfer resistance.The capability of the method for the detection of Srt A both in vitro and Staphylococcus aureus(S.aureus)has been demonstrated.Srt A with a concentration down to 1 pmol/L has been determined by the electrochemical analysis,which is lower than that achieved by the colorimetric assay(50 pmol/L).By integrating the advantages of homogeneous reaction and heterogeneous detection,the strategy serves as an ideal means for the fabrication of various sensing platforms by adopting biotin-labeled and sequence-specific peptide or nucleic acid substrates.

A simple and sensitive method for the determination of 4-n-octylphenol based on multi-walled carbon nanotubes modified glassy carbon electrode

A simple and sensitive electroanalytical method was presented for the determination of 4-n-octylphenol （OP） based on multi-walled carbon nanotubes （MWCNTs） modified glassy carbon electrode （GCE）. OP was directly oxidized on the MWCNTs/GCE, and the electrochemical oxidation mechanism was demonstrated by a one-electron and one-proton process in the reaction. The oxidation peak current of OP was significantly enhanced by the use of MWCNTs/GCE compared with those of bare glassy carbon electrode, suggesting that the modified electrode can remarkably improve the performance for OP determination. Factors influencing the detection processes were optimized. Under these optimal conditions, a linear relationship between concentration of OP and current response was obtained in the range of 5 × 10-8 to 1× 10-5 mol/L with a detection limit of 1.5 × 10-8 mol/L and correlation coefficient 0.9986. The modified electrode showed good selectivity, sensitivity, reproducibility and high stability.

Simultaneous determination of dihydroxybenzene isomers utilizing a thiadiazole film electrode

The present study reports a sensitive electro-analytical method for the simultaneous determination of dihydroxybenzene isomers by using a thiadiazole film electrode, which was readily prepared by electropolymerization of 2,5-dimercapto-1,3,4-thiadiazole on a glassy carbon electrode with cyclic voltammetry. The functionalized electrode has a distinguishable and sensitive response to dihydroxybenzene isomers. Under the optimized conditions, the linear stripping peak currents showed good linear relationships with hydroquinone, catechol and resorcinol at concentration ranges 0.50-120, 0.50-110 and 1.00-110 μmol/L, and the detection limits are 0.1, 0.1 and 0.3 μmol/L, respectively. The proposed method is applicable to the simultaneous determination of dihydroxybenzene isomers in real samples with the relative standard deviations of less than 5.7% and the recovery rates of 95.6%-106%. The constructed electrode is characterized by simple preparation, good selectivity, and high sensitivity advantages.

Polydopamine/carbon nanotube nanocomposite coating for corrosion resistance

Carbon nanotube(CNT)has excellent properties as a coating material.However,most methods for CNT coating have limitations.Recent studies have shown that polydopamine(PDA)can be used as a good and eco-friendly corrosion resistance coating material.However,the effect of PDA/CNT nanocomposite coating on the corrosion mitigation property of carbon steel(CS)remains unknown.Therefore,the objective of this study was to determine the effect of PDA/CNT nanocomposite coating on the corrosion mitigation property of carbon steel(CS).A dopamine(DA)/CNT composite was first synthesized.CNT length was controlled by sonication.Based on dynamic light scattering,field emission transmission electron microscopy,and atomic force microscopy analyses,average lengths of CNTs in long and short DA-CNTs were 500 and 50 nm,respectively.Carbon steel specimens were subjected to corrosion resistance analysis using electrochemical methods.Results of electrochemical tests showed that corrosion resistance of CS coated with PDA and PDA/CNTs were dramatically higher than those of bare CS.This corrosion mitigation was attributed to two mechanisms.First,PDA decreased the corrosion rate due to the generation of a thin and dense layer on the surface.Second,CNTs suppressed the cathodic partial reaction due to oxygen adsorption at defect sites of CNTs.

Inhibitory Effect of Vibrio neocaledinocus sp. and Pseudoalteromonas piscicida Dual-Species Biofilms on the Corrosion of Carbon Steel

Multi-species biofilms are found in various bacterial habitats and have industrial relevance. These complex bacterial communities have synergetic effects, unlike a single species. Therefore, it is critical to evaluate these complex communities as a whole. Here, the inhibitory eff ect of single-and dual-species biofilms of Vibrio neocaledinocus sp. and Pseudoalteromonas piscicida for A36 carbon steel corrosion was investigated. The results demonstrated that the synergistic interactions of the monoculture increased the overall biomass production of the dual-species biofilm, but the growth rate was reduced in the presence of the dual-species culture due to a lack of nutrients. Field emission scanning electron microscopy images also confirmed the development of biofilms—they became more homogenized via exposure time in both the mono-and dual-species cultures. The corrosion resistance of A36 carbon steel positively increased because of the dual-species interactions. This reached the highest value after four weeks of exposure. The highest corrosion inhibition e fficiency of 99.8% was achieved in the dual-species cultures. Microbial community analysis revealed the high relative abundance of Pseudoalteromonas piscicida during the initial days of exposure, demonstrating the dominant role of this bacterium in the biofilm structure.