Structure and electrochemical performance of delafossite AgFeO_(2)nanoparticles for supercapacitor electrodes

Delafossite AgFeO_(2)nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method.The resulting precursor was calcined at temperatures of 100,200,300,400,and 500℃to obtain the delafossite AgFe0_(2)phase.The morphology and microstructure of the prepared AgFeO_(2)samples were characterized by using field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),N_(2) adsorption/desorption,X-ray absorption spectroscopy(XAS),and Xray photoelectron spectroscopy(XPS)techniques.A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO_(2)nanoparticles in a 3 M KOH electrolyte.The delafossite AgFeO_(2)nanoparticles calcined at 100℃(AFO100)exhibited the highest surface area of 28.02 m^(2)·g^(-1)and outstanding electrochemical performance with specific capacitances of 229.71 F·g^(-1)at a current density of 1 A·g^(-1)and 358.32 F·g^(-1)at a scan rate of 2 mV·s^(-1).This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles,along with superior specific power and specific energy values of 797.46 W·kg^(-1)and 72.74Wh·kg^(-1),respectively.These findings indicate that delafossite AgFeO_(2)has great potential as an electrode material for supercapacitor applications.

Impact of Pollutant Concentration and Particle Deposition on the Radiative Flow of Casson-Micropolar Fluid between Parallel Plates

Assessing the behaviour and concentration of waste pollutants deposited between two parallel plates is essential for effective environmental management.Determining the effectiveness of treatment methods in reducing pollution scales is made easier by analysing waste discharge concentrations.The waste discharge concentration analysis is useful for assessing how effectively wastewater treatment techniques reduce pollution levels.This study aims to explore the Casson micropolar fluid flow through two parallel plates with the influence of pollutant concentration and thermophoretic particle deposition.To explore the mass and heat transport features,thermophoretic particle deposition and thermal radiation are considered.The governing equations are transformed into ordinary differential equations with the help of suitable similarity transformations.The Runge-Kutta-Fehlberg’s fourthfifth order technique and shooting procedure are used to solve the reduced set of equations and boundary conditions.The integration of a neural network model based on the Levenberg-Marquardt algorithm serves to improve the accuracy of predictions and optimize the analysis of parameters.Graphical outcomes are displayed to analyze the characteristics of the relevant dimensionless parameters in the current problem.Results reveal that concentration upsurges as the micropolar parameter increases.The concentration reduces with an upsurge in the thermophoretic parameter.An upsurge in the external pollutant source variation and the local pollutant external source parameters enhances mass transport.The surface drag force declines for improved values of porosity and micropolar parameters.

Association between intra-pancreatic fat deposition and diseases of the exocrine pancreas: A narrative review

Intrapancreatic fat deposition(IPFD)has garnered increasing attention in recent years.The prevalence of IPFD is relatively high and associated with factors such as obesity,age,and sex.However,the pathophysiological mechanisms underlying IPFD remain unclear,with several potential contributing factors,including oxida-tive stress,alterations in the gut microbiota,and hormonal imbalances.IPFD was found to be highly correlated with the occurrence and prognosis of exocrine pan-creatic diseases.Although imaging techniques remain the primary diagnostic approach for IPFD,an expanding array of biomarkers and clinical scoring systems have been identified for screening purposes.Currently,effective treatments for IPFD are not available;however,existing medications,such as glucagon-like peptide-1 receptor agonists,and new therapeutic approaches explored in animal models have shown considerable potential for managing this disease.This paper reviews the pathogenesis of IPFD,its association with exocrine pancreatic disea-ses,and recent advancements in its diagnosis and treatment,emphasizing the significant clinical relevance of IPFD.

Flexible free-standing graphene-like film electrode for supercapacitors by electrophoretic deposition and electrochemical reduction

Electrophoretic deposition in conjunction with electrochemical reduction was used to make flexible free-standing graphene-like films. Firstly, graphene oxide （GO） film was deposited on graphite substrate by electrophoretic deposition method, and then reduced by subsequent electrochemical reduction of GO to obtain reduced GO （ERGO） film with high electrochemical performance. The morphology, structure and electrochemical performance of the prepared graphene-like film were confirmed by SEM, XRD and FT-IR. These unique materials were found to provide high specific capacitance and good cycling stability. The high specific capacitance of 254 F/g was obtained from cyclic voltammetry measurement at a scan rate of 10 mV/s. When the current density increased to 83.3 A/g, the specific capacitance values still remained 132 F/g. Meanwhile, the high powder density of 39.1 kW/kg was measured at energy density of 11.8 W-h/kg in 1 mol/L H2SO4 solution. Furthermore, at a constant scan rate of 50 mV/s, 97.02% of its capacitance was retained for 1000 cycles. These promising results were attributed to the unique assembly structure of graphene film and low contact resistance, which indicated their potential application to electrochemical capacitors.

Electrochemical codeposition of Mg-Li-Gd alloys from LiCl-KCl-MgCl_2-Gd_2O_3 melts

Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was analyzed by X-ray diffraction （XRD）, optical microscopy （OM） and scanning electron microscopy （SEM）. The results show that magnesium and gadolinium deposit mainly in the first 30 min, and the alloy obtained contains 96.53% Mg, 0.27% Li and 3.20% Gd （mass fraction）. Then, the reduction of lithium ions occurs quickly. The composition of alloy can be adjusted by controlling electrolysis time or Gd 2 O 3 concentration in LiCl-KCl melts. With the addition of Gd into Mg-Li alloys, the corrosion resistance of the alloys is enhanced. XRD results suggest that Mg 3 Gd and Mg 2 Gd can be formed in Mg-Li-Gd alloys. The distribution of Gd element in Mg-Li-Gd alloys indicates that Gd element mainly distributes at the grain boundaries of Mg-Li-Gd alloys.

Electrochemical mechanism of electrolysis codeposition of Mg-Sr alloy in molten salt

The electrochemical process of Mg-Sr codeposition was studied in MgCl2-SrCl2-KCl melts containing different MgCl2 concentrations at 700 ℃ by cyclic voltammetry, chronopotentiometry and chronoamperometry. The results show that the actual precipitation potential of Sr reduces by nearly 0.5 V because of the depolarization effects of Sr activity reduced by forming Mg-Sr alloy. The codeposition potential condition of Mg and Sr to form Mg-Sr alloy is as follows： When electrode potential is more negative than -1.5 V, the magnesium will precipitate; when electrode potential is more negative than -2.0 V, the magnesium and strontium will both deposit. The control step of codeposition process of Mg and Sr is not diffusion control step. The codeposition current condition of Mg and Sr to form Mg-Sr alloy by chronoptentiometry is as follows： cathode current densities are higher than 0.71, 1.57 and 2.83 A/cm^2 in MgCl2-SrCl2-KCl melts with MgCl2 concentrations of 2%, 5% and 10% （mass fraction）, respectively. Key words：

Ag Deposition Forms and Uniformity on Porous Silicon by Electrochemical Method

The electrochemical deposition technique was applied to achieve porous silicon （PS） surface passivated with Ag deposition for improving the properties of PS photoluminescence. The relation of Ag depositing forms to current density and the effect of PS hydrophilic surface on deposition uniformity were investigated. The experimental results indicated that there were two critical current densities （maximum and minimum） in which Ag was absent and electroplated on PS surface correspondingly, and the range of current density for deposition of Ag on porous silicon was from 50 μA/cm^2 to 400 μA/cm^2. The process of changing PS surface from hydrophobic into hydrophilic had positive effect on Ag deposition uniformity. Under the same experimental conditions, PS hydrophobic surface presented uneven Ag deposition.However, hydrophilic surface treated with SC-1 solution was even. Finally, the effect of PS surface passivation with Ag even deposition on photoluminescence intensity and stabilization of PS was studied. It was discovered that Ag passivation inhibited the degradation of PL intensity effectively. In addition, excessive Ag deposition had a quenching effect on room-temperature visible photoluminescence of PS.

Electrochemical Deposition and Nucleation of Aluminum on Tungsten in Aluminum Chloride-Sodium Chloride Melts

Electrochemical deposition and nucleation of aluminum on tungsten electrode from AlCl3-NaCl melts were studied by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammetry and chronopotentiometry analyses showed that Al （Ⅲ） was reduced at 200℃ in two consecutive steps in an electrolyte of molten AlCl3-NaCl system with a composition 52：48 molar ratio. The current-time characteristics of nucleation aluminum on tungsten showed a strong dependence on overpotentials. Chronoamperometry showed that the deposition process of aluminum on tungsten was controlled by an instantaneous nucleation with a hemispherical diffusion-controlled growth mechanism. The results could lead to a better understanding of the AlCl3-NaCl melt system that has technological importance in electrodeposition of metals as well as in rechargeable batteries.

Synthesis of Biomimetic Superhydrophobic Surface through Electrochemical Deposition on Porous Alumina

The superhydrophobicity of plant leaves is a benefit of the hierarchical structures of their surfaces. These structures have been imitated in the creation of synthetic surfaces. In this paper, a novel process for fabrication of biomimetic hierarchical structures by electrochemical deposition of a metal on porous alumina is described. An aluminum specimen was anodically oxidized to obtain a porous alumina template, which was used as an electrode to fabricate a surface with micro structures through electrochemical deposition of a metal such as nickel and copper after the enlargement of pores. Astonishingly, a hier- archical structure with nanometer pillars and micrometer clusters was synthesized in the pores of the template. The nanometer pillars were determined by the nanometer pores. The lbrmation of micrometer clusters was related to the thin walls of the pores and the crystallization of the metal on a flat surface. From the as-prepared biomimetic surfaces, lotus-leaf-like superhydrophobic surfaces with nickel and copper deposition were achieved.

Synthesis of Zinc Oxide Nanostructures on Graphene/Glass Substrate via Electrochemical Deposition: Effects of Potassium Chloride and Hexamethylenetetramine as Supporting Reagents

The effects of the supporting reagents hexamethylenetetramine(HMTA)and potassium chloride(KCl)mixed in zinc nitrate hexahydrate(Zn(NO3)2 6H2O)on the morphological,structural,and optical properties of the resulting Zn O nanostructures electrodeposited on graphene/glass substrates were investigated.The supporting reagent HMTA does not increase the density of nanorods,but it does remarkably improve the smoothness of the top edge surfaces and the hexagonal shape of the nanorods even at a low temperature of 75°C.Hydroxyl(OH-)ions from the HMTA suppress the sidewall growth of non-polar planes and promote the growth of Zn O on the polar plane to produce vertically aligned nanorods along the c axis.By contrast,the highly electronegative chlorine(Cl-)ions from the supporting reagent KCl suppress the growth of Zn O on the polar plane and promote the growth on non-polar planes to produce vertical stacking nanowall structures.HMTA was found to be able to significantly improve the crystallinity of the grown Zn O structures,as indicated by the observation of much lower FWHM values and a higher intensity ratio of the emission in the UV region to the emission in the visible region.Equimolar mixtures of Zn(NO3)2 6H2O and the supporting reagents HMTA and KCl seem to provide the optimum ratio of concentrations for the growth of high-density,uniform Zn O nanostructures.The corresponding transmittances for such molar ranges are approximately 55–58%(HMTA)and 63–70%(KCl),which are acceptable for solar cell and optoelectronic devices.

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO_2 composite electrodeposition

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO2 composite electrodeposition in alkaline zincatesolutions were studied respectively by the methods of linear potential sweep and cyclic voltammetry. From the re-sults it can be concluded that Zn shows under potential deposition, Zn-Fe alloy codeposition is anomalous codeposi-tion and Zn-Fe alloy cathode polarization is increased with the introduction of additive. From the view point of elec-trochemistry, the reasons that the content of Fe in the Zn-Fe coating changes with the composition of the electrolyteand the process conditions altering and the relationship between the content of Fe and the appearance of the coatingare interpreted. The cathode polarization of Zn-Fe alloy codeposition is enhanced obviously with addition of additive.In the course of composite electrodeposition, TiO2 has less promotion to electrodeposition of zinc ions than to iron i-ons, while the electrodeposition of iron ions improves the content of TiO2 in composite coating, which is inagreement with the results of process experiments.

Online evaluation of electroless deposition rate by electrochemical noise method

Continuous noise resistance calculation(CNRC)technique was used for online determination of the electroless nickel deposition rate on zirconium pretreated magnesium alloy.For this purpose,the noise resistance(R_n) variation with time was calculated for the pretreated alloy surface in the electroless plating solution.The CNRC results were described by energy dispersive X-ray spectroscopy(EDS)and scanning electron microscopy(SEM)techniques.Also,potentiodynamic polarization and gravimetric measurements were used for determination of the electroless deposition rate at the same time period and the results were compared with the CNRC results.The Rn variation with plating time shows that the electroless plating consists of different stages with various deposition rates.The results of the CNRC and polarization methods were not in acceptable agreement due to the limitations of the polarization method for online monitoring of the deposition rate.However,the results of the gravimetric measurements were in complete agreement with the CNRC technique and so,the CNRC can be considered as suitable tool for online evaluation of the electroless deposition rate.

Hydroxyapatite Bioceramic Coatings Prepared by Hydrothermal-electrochemical Deposition Method

The hydroxyapatite（HA） ceramic coating was successfully prepared on Ti6A14V alloy by the hydrothermal-electrochemical deposition method with constant voltage model. The phases of deposits were analyzed by X-ray diffraction. The releationship between crystallinity and depositing temperature was discussed. The microstructures of hydroxyapatite coating were observed by scanning electron microscope. The experimental results showed that the phases, crystaUinity and morphologies of deposits were influenced by depositing temperature （100℃, 120℃, 140℃, 160℃, 180℃ and 200℃, respectively）. The special hydrothermal environment can lower the crystallization temperature of HA. The crystallinity of HA increases firstly and then decreases with the increase of temperature. There is little hydroxyapatite deposited on the Ti6A14V surface when the depositing temperature is 100℃. The HA deposition increases with the increase of the depositing temperature. And the HA morphologies are influenced by the depositing temperature.

Fabrication of Superhydrophobic Surfaces on Aluminum Alloy Via Electrodeposition of Copper Followed by Electrochemical Modification

Superhydrophobic aluminum surfaces have been prepared by means of electrodeposition of copper on aluminum surfaces, followed by electrochemical modification using stearic acid organic molecules. Scanning electron microscopy(SEM) images show that the electrodeposited copper films follow "island growth mode" in the form of microdots and their number densities increase with the rise of the negative deposition potentials. At an electrodeposition potential of-0.2 V the number density of the copper microdots are found to be 4.5×104cm^(-2)that are increased to 2.9×105cm^(-2)at a potential of-0.8 V. Systematically, the distances between the microdots are found to be reduced from 26.6 μm to 11.03 μm with the increase of negative electrochemical potential from-0.2 V to-0.8 V. X-ray diffraction(XRD) analyses have confirmed the formation of copper stearate on the stearic acid modified copper films. The roughness of the stearic acid modified electrodeposited copper films is found to increase with the increase in the density of the copper microdots. A critical copper deposition potential of-0.6 V in conjunction with the stearic acid modification provides a surface roughness of 6.2 μm with a water contact angle of 157?, resulting in superhydrophobic properties on the aluminum substrates.

Enhanced Photoelectrochemical Properties of Cu_2O-loaded Short TiO_2 Nanotube Array Electrode Prepared by Sonoelectrochemical Deposition

Copper and titanium remain relatively plentiful in earth crust.Therefore,using them in solar energy conversion technologies are of significant interest.In this work,cuprous oxide（Cu2O）-modified short TiO2 nanotube array electrode was prepared based on the following two design ideas:first,the short titania nanotubes obtained from sonoelectrochemical anodization possess excellent charge separation and transportation properties as well as desirable mechanical stability;second,the sonoelectrochemical deposition technique favours the improvement in the combination between Cu2O and TiO2 nanotubes,and favours the dispersion of Cu2O particles.UV-Vis absorption and photo-electronchemical measurements proved that the Cu2O coating extended the visible spectrum absorption and the solar spectrum-induced photocurrent response.Under AM1.5 irradiation,the photocurrent density of the composite electrode（i.e.sonoelectrochemical deposition for 5 min） was more than 4.75 times as high as the pure nanotube electrode.Comparing the photoactivity of the Cu2O/TiO2 electrode obtained using sonoelectrochemical deposition with others that synthesized using plain electrochemical deposition,the photocurrent density of the former electrode was 2.2 times higher than that of the latter when biased at 1.0 V（vs.Ag/AgCl）.The reproducible photocurrent response under intermittent illumination demonstrated the excellent stability of the composite electrode.Such kind of composite electrode material will have many potential applications in solar cell and other fields.

Excellent Electrochemical Performances of Intrinsic Polyaniline Nanofibers Fabricated by Electrochemical Deposition

A simple route to synthesize the polyaniline(PANI) nanofibers with diameter about 150 nm was reported. In this strategy, the PANI nanofibers were fabricated by electrochemical deposition by using two-electrode configuration in 0.01 M aniline and 0.01 M H_2SO_4 electrolytes. The as-prepared materials were characterized by scanning electron microscopy(SEM), infrared spectroscopy(FTIR), Raman spectroscopy and thermogravimetric analysis(TGA). The electrochemical properties of the PANI nanofibers electrode as supercapacitor materials were investigated. The PANI nanofibers electrode showed high capacitance of 485 F·g^(-1)at 0.1 A·g^(-1), and the decrease in the specific capacitance is about 3.5% in 1 000 cycles. The results indicate that the PANI nanofibers electrode shows high stability and retains its electrochemical capacitance property over 1 000 cycles, suggesting PANI nanofibers have promising applications in high-performance supercapacitors.

Thermo-Electrochemical Cells Based on Carbon Nanotube Electrodes by Electrophoretic Deposition

Drawbacks of low efficiency and high cost of the electrode materials have restricted the wide applications of the thermo-electrochemical cells(TECs). Due to high specific areas and electrical conductivities, the low cost multi-walled carbon nanotubes(MWNTs) are promising alternative electrode materials. In this work, the MWNT films of up to 16 cm^2 were synthesized on stainless steel substrates by the electrophoretic deposition(EPD) to make the thermo-electrochemical electrodes. MWNT electrodes based on TECs were characterized by cyclic voltammetry and the long-term stability tests with the potassium ferri/ferrocyanide electrolyte. The TECs reached the current density of 45.2 A m^(-2) and the maximum power density of 0.82 W m^(-2). The relative power conversion efficiency of the MWNT electrode is 50 % higher than that for the Pt electrode. Meanwhile, the TECs was operated continuously for 300 h without performance degradation. With the priorities of low cost and simple fabrication, EPD-based MWNT TECs may become commercially viable.

Highly Enhanced Visible-Light-Driven Photoelectrochemical Performance of ZnO-Modified In_2S_3 Nanosheet Arrays by Atomic Layer Deposition

Photoanodes based on In_2S_3/ZnO heterojunction nanosheet arrays(NSAs) have been fabricated by atomic layer deposition of ZnO over In_2S_3 NSAs, which were in situ grown on fluorine-doped tin oxide glasses via a facile solvothermal process. The as-prepared photoanodes show dramatically enhanced performance for photoelectrochemical(PEC) water splitting, compared to single semiconductor counterparts. The optical and PEC properties of In_2S_3/ZnO NSAs have been optimized by modulating the thickness of the Zn O overlayer. After pairing with ZnO, the NSAs exhibit a broadened absorption range and an increased light absorptance over a wide wavelength region of 250–850 nm. The optimized sample of In_2S_3/ZnO-50 NSAs shows a photocurrent density of 1.642 m A cm^(-2)(1.5 V vs. RHE) and an incident photonto-current efficiency of 27.64% at 380 nm(1.23 V vs.RHE), which are 70 and 116 times higher than those of the pristine In_2S_3 NSAs, respectively. A detailed energy band edge analysis reveals the type-II band alignment of the In_2S_3/ZnO heterojunction, which enables efficient separation and collection of photogenerated carriers,especially with the assistance of positive bias potential, and then results in the significantly increased PEC activity.

Electrochemical deposition of Mg(OH)_(2)/GO composite films for corrosion protection of magnesium alloys

Mg(OH)_(2)/graphene oxide(GO)composite film was electrochemical deposited on AZ91D magnesium alloys at constant potential.The characteristics of the Mg(OH)_(2)/GO composite film were investigated by scanning electron microscope(SEM),energy-dispersive X-ray spectrometry(EDS),X-ray diffractometer(XRD)and Raman spectroscopy.It was shown that the flaky GO randomly distributed in the composite film.Compared with the Mg(OH)_(2)film,the Mg(OH)_(2)/GO composite film exhibited more uniform and compact structure.Potentiodynamic polarization tests revealed that the Mg(OH)_(2)/GO composite film could significantly improve the corrosion resistance of Mg(OH)_(2)film with an obvious positive shift of corrosion potential by 0.19 V and a dramatic reduction of corrosion current density by more than one order of magnitude.

HA coating on titanium with nanotubular anodized TiO_2 intermediate layer via electrochemical deposition

Hydroxyapatite(HA) coating has been prepared on titanium substrate through an electrochemical deposition approach. In order to improve the bonding strength between HA coating and Ti substrate, a well oriented and uniform titanium oxide nanotube array on the surface of titanium substrate was applied by means of anodic oxidation pre-treatment. Then the calcium hydrogen phosphate(CaHPO4·2H2O, DCPD) coating, as the precursor of hydroxyapatite coating, was electrodeposited on the anodized Ti. At the initial stage of electro-deposition, the DCPD crystals, in nanometer precipitates, are anchored in and between the tubes. With increasing the deposition time, the nanometer DCPD crystals are connected together to form a continuous coating on titanium oxide nanotube array. Finally, the DCPD coating is converted into hydroxyapatite one simply by being immersed in alkaline solution.