Flow anodic oxidation system has demonstrated to be a promising and environmental benign water treatment technology because of its advantages of high contaminant removal efficiency and low energy consumption.However,t...Flow anodic oxidation system has demonstrated to be a promising and environmental benign water treatment technology because of its advantages of high contaminant removal efficiency and low energy consumption.However,traditional setup needs an external unit for flow anode material separation and recovery,which inevitably increases the capital cost and hinders its continuous operation.Herein,a specific porous cathode is introduced to achieve continuous water purification with high contaminant removal in a flow anodic oxidation system.The efuent concentration of carbamazepine(CBZ),a common and model contaminant widely detected in natural water environment,was reduced by 99%.The linear sweep voltammetry(LSV)and quenching tests demonstrated that HO·was the dominant reactive species.While the removal of contaminants was inhibited in practical surface water,largely related to the quenching by dissolved organic matter and bicarbonate,the flow anodic oxidation process was competent in alleviating the ecotoxicity following oxidation.Our study constructs a modular device for cost-effective continuous water purification and provides insight into the mechanisms of flow andic oxidation.展开更多
Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile me...Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data encryption.However,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing times.In contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient conditions.By means of the anodizing technique,oxide films,oxide nanotubes,nanowires and nanodots can be fabricated to prepare memristors.Oxide film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and time.Thus memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield rate.This article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of memristors.Firstly,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features and challenges of anodic oxidation for memristor production are elaborated.展开更多
Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is cruci...Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.展开更多
Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid＋citric acid mixed solution.The microstructure and crystallinity of...Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid＋citric acid mixed solution.The microstructure and crystallinity of the resulting anodized film were examined by TEM and XRD.The special capacitance,resistance and withstanding voltage of the film were explored with electrochemical impedance spectroscopy（EIS）,LCR meter and small-current charging.The results show that the high voltage anodized oxide film consists of an inner layer with high crystallinity and an outer layer with low crystallinity.However,the crystallinity of the film formed in boric acid＋citric acid mixed solution is higher than that of the film formed in only boric acid solution,leading to an increase in film＇s field strength and special capacitance.Meanwhile,there are more defects from phase transformation in the out layer of the film formed in boric acid＋citric acid mixed solution than in that of film formed in only boric acid solution,leading to a decrease in film＇s resistance and withstanding voltage.展开更多
The special experimental device and sulfuric acid electrolyte were adopted to study the influence of anodic oxidation heat on hard anodic film for 2024 aluminum alloy. Compared with the oxidation heat transferred to t...The special experimental device and sulfuric acid electrolyte were adopted to study the influence of anodic oxidation heat on hard anodic film for 2024 aluminum alloy. Compared with the oxidation heat transferred to the electrolyte through anodic film, the heat transferred to the coolant through aluminum substrate is more beneficial to the growth of anodic film. The film forming speed, film thickness, density and hardness are significantly increased as the degree of undercooling of the coolant increases. The degree of undercooling of the coolant, which is necessary for the growth of anodic film, is related to the degree of undercooling of the electrolyte, thickness of aluminum substrate, thickness of anodic film, natural parameters of bubble covering and current density. The microstructure and performance of the oxidation film could be controlled by the temperature of the coolant.展开更多
Nickel nanowire and nanotube arrays as supports for Pt-Pd catalyst were prepared by elec- troless deposition with anodic aluminum oxide template. Pt-Pd composite catalyst was de- posited on the arrays by displacement ...Nickel nanowire and nanotube arrays as supports for Pt-Pd catalyst were prepared by elec- troless deposition with anodic aluminum oxide template. Pt-Pd composite catalyst was de- posited on the arrays by displacement reaction. SEM images show that the nickel nanowires have an average diameter of I00 nm and the nickel nanotubes have an average inner diameter of 200 nm. EDS scanning reveals that elemental Pt and Pd disperse uniformly on the arrays. Cyclic voltammetry study indicates that the nickel nanotube array loaded with Pt-Pd pos- sesses a higher electrochemical activity for ethanol oxidation than the nickel nanowire array with Pt-Pd.展开更多
Boron-doped diamond （BDD） electrocatalysis is combined with photocatalysis using titanium dioxide （TiO2） as a catalyst to improve pollutant-oxidation efficiency. Phenol solution is chosen as model wastewater. Diff...Boron-doped diamond （BDD） electrocatalysis is combined with photocatalysis using titanium dioxide （TiO2） as a catalyst to improve pollutant-oxidation efficiency. Phenol solution is chosen as model wastewater. Different methods involving BDD and/or TiO2 during the degradation processes are compared. Parameters such as the currency density and initial concentration are varied in order to determine their effects on the oxidation process. Moreover, the degradation kinetics of phenol is experimentally studied. The results reveal the superiority of series combination of BDD and TiO2, especially the treatment process of electrocatalysis and succedent photocatalysis, and the optimum working currency density for electrocatalysis is 25.48 mA/cm2. The removal rate decreases with the increase in the initial phenol concentration and the degradation reaction follows quasi-first-order kinetics equation.展开更多
Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered in- termetallic particles were examined by scanning electron microscopy （SEM） and energy dis...Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered in- termetallic particles were examined by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） after pretreatment. The anodic film was investigated by transmission electron microscopy （TEM）, and its corrosion resistance was analyzed by electrochemical impedance spectroscopy （EIS） and Tafel polarization in NaC1 solution. The results show that the size of A1-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the an- odic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.展开更多
Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The pho...Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The phosphor chromic acid weight loss method was used to evaluate the sealing effects.Using electron scanning microscopy(SEM),the surface and cross-sectional micromorphologies of the anodic oxidation films sealed by different fluorozirconate sealants were observed.The position and state of zirconium element distribution in the film hole were investigated by the further quantitative and distribution analysis of Zr element.This study provides an experimental evidence for the theoretical studies of fluorozirconate-sealed anodic oxidation films.It is shown that the fluorozirconate has good sealing effects and has a wide prospect for sealing the aluminum alloy samples.Its products were highly corrosion resistant,and were filled in the openings of the micropores in the oxide film.展开更多
Anatase titanium dioxide is an active photocatalyst, however, it is difficult to be immobilized on the substrate. The crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidat...Anatase titanium dioxide is an active photocatalyst, however, it is difficult to be immobilized on the substrate. The crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation. The film was then used for photocatalysis via the methyl orange degradation method. The effects of anodization voltage, pH value, TiO2 film area and degradation time on the photocatalyst were investigated respectively by UV-visible spectrum. It was indicated that the TiO2 film prepared by anodic oxidation at 140 V had the best photocatalysis capability and the degradation of methyl orange was accelerated with acid addition.展开更多
The anodic oxidation of aqueous solutions containing dimethyl phthalate （DMP） up to 125 mg/L with sodium sulfate （Na2SO4） as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment ...The anodic oxidation of aqueous solutions containing dimethyl phthalate （DMP） up to 125 mg/L with sodium sulfate （Na2SO4） as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond （BDD） as anode. Electrolyses were carded out at constant current density （1.5-4.5 mA/cm^2）. Complete mineralization was always achieved owing to the great concentration of hydroxyl radical （-OH） generated at the BDD surface. The effects of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency were investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography （HPLC） revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography- Mass Spectrometry （GC-MS） and a general pathway for the electrochemical incineration of DMP on BDD was proposed.展开更多
In this study,advanced oxidation processes(AOPs) such as anodic oxidation(AO),UV/H_2O_2 and Fenton processes(FP) were investigated for the degradation of salicylic acid(SA) in lab-scale experiments.Boron-doped diamond...In this study,advanced oxidation processes(AOPs) such as anodic oxidation(AO),UV/H_2O_2 and Fenton processes(FP) were investigated for the degradation of salicylic acid(SA) in lab-scale experiments.Boron-doped diamond(BDD) film electrodes using Ta as substrates were employed for AO of SA.In the case of FP and UV/H_2O_2,most favorable experimental conditions were determined for each process and these were used for comparing with AO process.The study showed that the FP was the most effective process under aci...展开更多
The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction co...The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.展开更多
Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this...Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this work. Constant voltage and constant current anodic oxidation were adopted with sulphuric acid used as the electrolyte, pure titanium as the anode and copper as the cathode. The morphology and structure of the porous film on the substrate were analyzed with the aid of Field Emission Scanning Electron Microscopy （FESEM） and X-ray Diffraction （XRD）. The effects of the parameters of anodic oxidation （such as voltage, the concentration of sulphuric acid, anodization time and current density） on the aperture and the crystalline phase of the TiO2 porous film were systematically investigated. The results indicate that the increase of current density facilitates the augment of the aperture and the generation of anatase and mille. In addition, the forming mechanism of anatase and mille TiO2 porous films was discussed.展开更多
The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The c...The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.展开更多
Ti-Cu alloy has potential to be used in plastic surgery and dental implants due to its strong antibacterialproperties,high strength and good corrosion resistance.In this paper,Ti-5Cu was anodic-oxidized to enhance the...Ti-Cu alloy has potential to be used in plastic surgery and dental implants due to its strong antibacterialproperties,high strength and good corrosion resistance.In this paper,Ti-5Cu was anodic-oxidized to enhance the surface compatibility.The influence of the oxidation on the corrosion resistance,antibacterial properties and biological properties was investigated.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)results showed that a double-layer oxide coating with dense inner layer and porous outside layer was formed on Ti-Cu sample.The oxide coating consisted mainly of TiO2,CuzO and small amount of CuO,improved the corrosion resistance of Ti-Cu alloy by one order of magnitude due to the formation of the dense oxide inner layer,but high Cu ion release was detected.The plate count results showed that the antibac-terial activity of Ti-Cu sample was improved to≥99%due to the comprehensive function of CuO and Cu_(2)O in the coating and Cu^(2+)release.Cell test results showed that thecoating exhibited good cell compatibility,the porous sur-face structure improved the adhesion of cells,and Cu ion release promoted the cell proliferation.展开更多
Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface s...Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface structures, surface morphology and residual mechanical properties were characterized. The crystallite size （La） of carbon fibers would be interrupted due to excessive electrochemical etching, while the crystallite spacing （d（002）） increased as increasing current density. The disordered structures on the surface of carbon fiber with rough surface increased at the initial oxidation stage and then removed by further electrochemical etching, which resulting in continuous increase of the extent of graphitization on the fiber surface. However, the electrochemical etching was beneficial to getting ordered morphology on the surface for carbon fiber with smooth surface, especially when the current density was lower than 1.77 A/m 2 . The tensile strength and tensile modulus could be improved by 17.27% and 5.75%, respectively, and was dependent of surface morphology. The decreasing density of carbon fibers probably resulted from the volume expansion of carbon fibers caused by the abundant oxygen functional groups intercalated between the adjacent graphite layers.展开更多
The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance ...The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.展开更多
The electrochemical mechanism of anode oxidation of HCHO in electroless copper plating solution with N, N, N′, N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) was investigated by measuring cyclic voltammetry cur...The electrochemical mechanism of anode oxidation of HCHO in electroless copper plating solution with N, N, N′, N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) was investigated by measuring cyclic voltammetry curves and anodic polarization curves. Three different oxidation peaks occur at the potentials of -0.62 V (Peak 1), -0.40 V (Peak 2) and -0.17 V (Peak 3) in the anode oxidation process of THPED-containing solution. The reaction at Peak 1, a main oxidation reaction, is the irreversible reaction of adsorbed HCHO with hydrogen evolution. The reaction at Peak 2, a secondary oxidation reaction, is the quasi-reversible reaction of adsorbed HCHO without hydrogen evolution. The reaction at Peak 3 is the irreversible oxidation of anode copper. The current density of Peak 1 increases gradually, that of Peak 2 remains constant and that of Peak 3 decreases with the increase of HCHO concentration. The current density of Peak 3 increases with the increase of THPED concentration and the complexation of THPED promotes the dissolution of anode copper.展开更多
In order to analyze the influence of the anodizing process on the thermal load of an aluminum alloy piston,dedicated temperature tests have been carried out using the Hardness Plug method and the results for the anodi...In order to analyze the influence of the anodizing process on the thermal load of an aluminum alloy piston,dedicated temperature tests have been carried out using the Hardness Plug method and the results for the anodized piston have been compared with those obtained separately for an original aluminum piston.In addition,numerical simulations have been conducted to analyze the temperature field and thermal stress distribution.Simulations and experiments show that the maximum temperature of the anodized piston is 16.36%and 5.4%smaller than that of the original piston under the condition of maximum torque and maximum power,respectively.The thermal stress of the temperature field of both pistons is within 50 Mpa,which meets the strength requirements of the material at high temperature.However,the area with significant thermal stress of the anodized piston is significantly smaller than that of the original piston.Combined with the fatigue analysis data,it can be seen that the safety factor of the anodized piston greater than 1.8 is 99.13%.Therefore,adopting the anodizing process not only reduces the piston thermal load,but also helps to extend its life and improve its reliability.展开更多
基金financially supported by the Basic Science Center Project of the National Natural Science Foundation of China(No.52388101)Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08L213)the National Natural Science Foundation of China(No.52100030)。
文摘Flow anodic oxidation system has demonstrated to be a promising and environmental benign water treatment technology because of its advantages of high contaminant removal efficiency and low energy consumption.However,traditional setup needs an external unit for flow anode material separation and recovery,which inevitably increases the capital cost and hinders its continuous operation.Herein,a specific porous cathode is introduced to achieve continuous water purification with high contaminant removal in a flow anodic oxidation system.The efuent concentration of carbamazepine(CBZ),a common and model contaminant widely detected in natural water environment,was reduced by 99%.The linear sweep voltammetry(LSV)and quenching tests demonstrated that HO·was the dominant reactive species.While the removal of contaminants was inhibited in practical surface water,largely related to the quenching by dissolved organic matter and bicarbonate,the flow anodic oxidation process was competent in alleviating the ecotoxicity following oxidation.Our study constructs a modular device for cost-effective continuous water purification and provides insight into the mechanisms of flow andic oxidation.
基金supported by the National Key Research and Development Program of China (Grant No.2018YFE0203802)Natural Science Foundation of Hubei Province, China (Grant No.2022CFA031)Dongguan Innovative Research Team Program (2020607101007)。
文摘Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data encryption.However,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing times.In contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient conditions.By means of the anodizing technique,oxide films,oxide nanotubes,nanowires and nanodots can be fabricated to prepare memristors.Oxide film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and time.Thus memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield rate.This article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of memristors.Firstly,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features and challenges of anodic oxidation for memristor production are elaborated.
文摘Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.
基金Project supported by University New Materials Disciplines Construction Program of Beijing Region
文摘Aluminum capacitor foils with a tunnel etch structure were reacted with boiling water and then anodized at 530 V in boric acid solution or boric acid＋citric acid mixed solution.The microstructure and crystallinity of the resulting anodized film were examined by TEM and XRD.The special capacitance,resistance and withstanding voltage of the film were explored with electrochemical impedance spectroscopy（EIS）,LCR meter and small-current charging.The results show that the high voltage anodized oxide film consists of an inner layer with high crystallinity and an outer layer with low crystallinity.However,the crystallinity of the film formed in boric acid＋citric acid mixed solution is higher than that of the film formed in only boric acid solution,leading to an increase in film＇s field strength and special capacitance.Meanwhile,there are more defects from phase transformation in the out layer of the film formed in boric acid＋citric acid mixed solution than in that of film formed in only boric acid solution,leading to a decrease in film＇s resistance and withstanding voltage.
基金Project (SBZDPY-11-17) supported by the Fund on Key Laboratory Project for Hydrodynamic Force, Ministry of Education, China Project (SZD0502-09-0) supported by Key Disciplines of Materials Processing Engineering of Sichuan Province, China
文摘The special experimental device and sulfuric acid electrolyte were adopted to study the influence of anodic oxidation heat on hard anodic film for 2024 aluminum alloy. Compared with the oxidation heat transferred to the electrolyte through anodic film, the heat transferred to the coolant through aluminum substrate is more beneficial to the growth of anodic film. The film forming speed, film thickness, density and hardness are significantly increased as the degree of undercooling of the coolant increases. The degree of undercooling of the coolant, which is necessary for the growth of anodic film, is related to the degree of undercooling of the electrolyte, thickness of aluminum substrate, thickness of anodic film, natural parameters of bubble covering and current density. The microstructure and performance of the oxidation film could be controlled by the temperature of the coolant.
文摘Nickel nanowire and nanotube arrays as supports for Pt-Pd catalyst were prepared by elec- troless deposition with anodic aluminum oxide template. Pt-Pd composite catalyst was de- posited on the arrays by displacement reaction. SEM images show that the nickel nanowires have an average diameter of I00 nm and the nickel nanotubes have an average inner diameter of 200 nm. EDS scanning reveals that elemental Pt and Pd disperse uniformly on the arrays. Cyclic voltammetry study indicates that the nickel nanotube array loaded with Pt-Pd pos- sesses a higher electrochemical activity for ethanol oxidation than the nickel nanowire array with Pt-Pd.
基金The Key Project of Chinese Ministry of Education (No.108601)Major Projects of National Water Pollution Control and Management Technology (No.2009ZX07101-011)Specialized Research Fund for the Doctoral Program of Higher Education (No.20060286010)
文摘Boron-doped diamond （BDD） electrocatalysis is combined with photocatalysis using titanium dioxide （TiO2） as a catalyst to improve pollutant-oxidation efficiency. Phenol solution is chosen as model wastewater. Different methods involving BDD and/or TiO2 during the degradation processes are compared. Parameters such as the currency density and initial concentration are varied in order to determine their effects on the oxidation process. Moreover, the degradation kinetics of phenol is experimentally studied. The results reveal the superiority of series combination of BDD and TiO2, especially the treatment process of electrocatalysis and succedent photocatalysis, and the optimum working currency density for electrocatalysis is 25.48 mA/cm2. The removal rate decreases with the increase in the initial phenol concentration and the degradation reaction follows quasi-first-order kinetics equation.
基金financially supported by the National Natural Science Foundation of China(No.51271012)
文摘Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered in- termetallic particles were examined by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） after pretreatment. The anodic film was investigated by transmission electron microscopy （TEM）, and its corrosion resistance was analyzed by electrochemical impedance spectroscopy （EIS） and Tafel polarization in NaC1 solution. The results show that the size of A1-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the an- odic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.
基金financially supported by the National New Material Testing and Evaluation Platform Main Center Project(No.TC170A5SU-1)。
文摘Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The phosphor chromic acid weight loss method was used to evaluate the sealing effects.Using electron scanning microscopy(SEM),the surface and cross-sectional micromorphologies of the anodic oxidation films sealed by different fluorozirconate sealants were observed.The position and state of zirconium element distribution in the film hole were investigated by the further quantitative and distribution analysis of Zr element.This study provides an experimental evidence for the theoretical studies of fluorozirconate-sealed anodic oxidation films.It is shown that the fluorozirconate has good sealing effects and has a wide prospect for sealing the aluminum alloy samples.Its products were highly corrosion resistant,and were filled in the openings of the micropores in the oxide film.
基金This work was financially supported by the Natural Science Foundation of Jiangsu Province (No. BK2004129) the Aviation Science Foundation of China (No. 04H52059).
文摘Anatase titanium dioxide is an active photocatalyst, however, it is difficult to be immobilized on the substrate. The crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation. The film was then used for photocatalysis via the methyl orange degradation method. The effects of anodization voltage, pH value, TiO2 film area and degradation time on the photocatalyst were investigated respectively by UV-visible spectrum. It was indicated that the TiO2 film prepared by anodic oxidation at 140 V had the best photocatalysis capability and the degradation of methyl orange was accelerated with acid addition.
基金supported by the National Natural Science Foundation of China (No 50778172) the Funds for Creative Research Groups of China (No 50621804)
文摘The anodic oxidation of aqueous solutions containing dimethyl phthalate （DMP） up to 125 mg/L with sodium sulfate （Na2SO4） as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond （BDD） as anode. Electrolyses were carded out at constant current density （1.5-4.5 mA/cm^2）. Complete mineralization was always achieved owing to the great concentration of hydroxyl radical （-OH） generated at the BDD surface. The effects of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency were investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography （HPLC） revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography- Mass Spectrometry （GC-MS） and a general pathway for the electrochemical incineration of DMP on BDD was proposed.
文摘In this study,advanced oxidation processes(AOPs) such as anodic oxidation(AO),UV/H_2O_2 and Fenton processes(FP) were investigated for the degradation of salicylic acid(SA) in lab-scale experiments.Boron-doped diamond(BDD) film electrodes using Ta as substrates were employed for AO of SA.In the case of FP and UV/H_2O_2,most favorable experimental conditions were determined for each process and these were used for comparing with AO process.The study showed that the FP was the most effective process under aci...
基金financially supported by the National Natural Science Foundation of China (Nos. 2127222, 91213303, 21172205, J1030412)
文摘The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.
文摘Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this work. Constant voltage and constant current anodic oxidation were adopted with sulphuric acid used as the electrolyte, pure titanium as the anode and copper as the cathode. The morphology and structure of the porous film on the substrate were analyzed with the aid of Field Emission Scanning Electron Microscopy （FESEM） and X-ray Diffraction （XRD）. The effects of the parameters of anodic oxidation （such as voltage, the concentration of sulphuric acid, anodization time and current density） on the aperture and the crystalline phase of the TiO2 porous film were systematically investigated. The results indicate that the increase of current density facilitates the augment of the aperture and the generation of anatase and mille. In addition, the forming mechanism of anatase and mille TiO2 porous films was discussed.
文摘The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.
基金This work was financially supported by the National Natural Science Foundation of China(No.31971253)Beijing Municipal Health Commission(Nos.BMHC-2019-9,BMHC-2018-4 and PXM2020-026275-000002).
文摘Ti-Cu alloy has potential to be used in plastic surgery and dental implants due to its strong antibacterialproperties,high strength and good corrosion resistance.In this paper,Ti-5Cu was anodic-oxidized to enhance the surface compatibility.The influence of the oxidation on the corrosion resistance,antibacterial properties and biological properties was investigated.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)results showed that a double-layer oxide coating with dense inner layer and porous outside layer was formed on Ti-Cu sample.The oxide coating consisted mainly of TiO2,CuzO and small amount of CuO,improved the corrosion resistance of Ti-Cu alloy by one order of magnitude due to the formation of the dense oxide inner layer,but high Cu ion release was detected.The plate count results showed that the antibac-terial activity of Ti-Cu sample was improved to≥99%due to the comprehensive function of CuO and Cu_(2)O in the coating and Cu^(2+)release.Cell test results showed that thecoating exhibited good cell compatibility,the porous sur-face structure improved the adhesion of cells,and Cu ion release promoted the cell proliferation.
基金supported by the National Basic Research Program of China (No. 2011CB605602)
文摘Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface structures, surface morphology and residual mechanical properties were characterized. The crystallite size （La） of carbon fibers would be interrupted due to excessive electrochemical etching, while the crystallite spacing （d（002）） increased as increasing current density. The disordered structures on the surface of carbon fiber with rough surface increased at the initial oxidation stage and then removed by further electrochemical etching, which resulting in continuous increase of the extent of graphitization on the fiber surface. However, the electrochemical etching was beneficial to getting ordered morphology on the surface for carbon fiber with smooth surface, especially when the current density was lower than 1.77 A/m 2 . The tensile strength and tensile modulus could be improved by 17.27% and 5.75%, respectively, and was dependent of surface morphology. The decreasing density of carbon fibers probably resulted from the volume expansion of carbon fibers caused by the abundant oxygen functional groups intercalated between the adjacent graphite layers.
基金Funded by the National Natural Science Foundation of China(No.12175107)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(No.NY220030)
文摘The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.
基金Project(200501045) supported by Innovation Fund of Guangdong Province of China
文摘The electrochemical mechanism of anode oxidation of HCHO in electroless copper plating solution with N, N, N′, N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) was investigated by measuring cyclic voltammetry curves and anodic polarization curves. Three different oxidation peaks occur at the potentials of -0.62 V (Peak 1), -0.40 V (Peak 2) and -0.17 V (Peak 3) in the anode oxidation process of THPED-containing solution. The reaction at Peak 1, a main oxidation reaction, is the irreversible reaction of adsorbed HCHO with hydrogen evolution. The reaction at Peak 2, a secondary oxidation reaction, is the quasi-reversible reaction of adsorbed HCHO without hydrogen evolution. The reaction at Peak 3 is the irreversible oxidation of anode copper. The current density of Peak 1 increases gradually, that of Peak 2 remains constant and that of Peak 3 decreases with the increase of HCHO concentration. The current density of Peak 3 increases with the increase of THPED concentration and the complexation of THPED promotes the dissolution of anode copper.
文摘In order to analyze the influence of the anodizing process on the thermal load of an aluminum alloy piston,dedicated temperature tests have been carried out using the Hardness Plug method and the results for the anodized piston have been compared with those obtained separately for an original aluminum piston.In addition,numerical simulations have been conducted to analyze the temperature field and thermal stress distribution.Simulations and experiments show that the maximum temperature of the anodized piston is 16.36%and 5.4%smaller than that of the original piston under the condition of maximum torque and maximum power,respectively.The thermal stress of the temperature field of both pistons is within 50 Mpa,which meets the strength requirements of the material at high temperature.However,the area with significant thermal stress of the anodized piston is significantly smaller than that of the original piston.Combined with the fatigue analysis data,it can be seen that the safety factor of the anodized piston greater than 1.8 is 99.13%.Therefore,adopting the anodizing process not only reduces the piston thermal load,but also helps to extend its life and improve its reliability.
