We proposed an empirical equation for a fine-structure constant: . Then, . where m<sub>p</sub> and m<sub>e</sub> are the rest mass of a proton and the rest mass of an electron, respectively. In...We proposed an empirical equation for a fine-structure constant: . Then, . where m<sub>p</sub> and m<sub>e</sub> are the rest mass of a proton and the rest mass of an electron, respectively. In this report, using the electrochemical method, we proposed an equivalent circuit. Then, we proposed a refined version of our own old empirical equations about the electromagnetic force and gravity. Regarding the factors of 9/2 and π, we used 3.132011447 and 4.488519503, respectively. The calculated values of T<sub>c</sub> and G are 2.726312 K and 6.673778 × 10<sup>-11</sup> (m<sup>3</sup>⋅kg<sup>-1</sup>⋅s<sup>-2</sup>).展开更多
Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite has been synthesized through electrochemical method and characterized by UV-Visible spectroscopy, XRD, SEM and EDAX data. U...Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite has been synthesized through electrochemical method and characterized by UV-Visible spectroscopy, XRD, SEM and EDAX data. UV-Visible spectroscopy measurements reveal that the Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite has maximum absorption at 353.04 nm and this peak position reflects the band gap of particles and it is found to be 2.51 eV which was calculated using Tauc plot. X-Ray diffraction (XRD) reveals crystaline size to be 49.85 nm which was calculated using Williamson-Hall (W-H) plot method. Photocatalytic degradation of acetic acid, chloroacetic acid and trichloroacetic acid has been studied by volumetric method using NaOH solution. Photocatalytic degradation of chloroacetic acid and acetic acid follows first order kinetics. The photodegradation efficiency for Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite was found to be ≈97.8%. A Taft linear free energy relationship is noted for the catalysed reaction with ρ* = 0.233 and indicating electron withdrawing groups enhance the rate. An isokinetic relation is observed with β = 358 K indicating that enthalpy factor controls the reaction rate. The result of this paper suggests the possibility of degradation of organic compounds, industrial effluants and toxic organic compounds by photodegradation process by ecofriendly Al<sub>2</sub>S<sub>3</sub>/ MoS<sub>2</sub>. The antibacterial activity of Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite was investigated. These particles were shown to have an effective bactericide.展开更多
The existence of inclusion influences the properties of aluminum alloy castings,from which the castings will face scrapping under severe condition.Great efforts on the inclusions in aluminum alloy were made and many i...The existence of inclusion influences the properties of aluminum alloy castings,from which the castings will face scrapping under severe condition.Great efforts on the inclusions in aluminum alloy were made and many inclusion assessment methods were put forward.However,most of the current methods are characterized by time consuming and expensive equipment cost,which limits the application in aluminum industry.Since the aluminum properties are sensitive to the inclusion,this paper tries to establish a new kind of inclusion assessment method.The inclusions were introduced to aluminum melts by adding aluminum scraps.The samples with different inclusion contents were prepared.The microstructure contained inclusions was observed.The inclusion was automatically identified with an image analyzer by setting different grey threshold value,and the inclusion content was obtained.The image analysis shows that inclusions wreck the continuity of the alloy matrix seriously,and the inclusion area percentage increases with the increasing of aluminum scraps.The high and low polarization measurements were conducted in 3.5 wt% NaCl aqueous solution at the temperature of 25 ℃.The electrochemical parameters of the testing materials,such as corrosion potential E k,corrosion current density I k and the linear polarization resistance R p,were obtained.The polarization measurement results show that the linear polarization resistances decrease,the corrosion potentials move towards more negative direction,and the corrosion current densities increase with the increasing of inclusion content.The theoretical analysis of the inclusion content and the corrosion current density was performed.The existence of inclusions makes the microstructure form corrosion microcells between the alloy matrix and inclusions.The impressed current can accelerate the current velocity or corrosion current density.The regression model of the inclusion contents vs.the corrosion current density was obtained.This model can be used to quantitatively analyze the inclusion content in aluminum alloys on the basis of inclusion sensitivity to the inclusion content.It is confirmed that the electrochemical method for inclusion assessment (EcMIA) is simple and reliable,which can provide a new solution for inclusion assessment in aluminum alloy.展开更多
A convenient method for methane(CH_(4))direct conversion to methanol(CH_(3)OH)is of great significance to use methane-rich resources,especially clathrates and stranded shale gas resources located in remote regions.The...A convenient method for methane(CH_(4))direct conversion to methanol(CH_(3)OH)is of great significance to use methane-rich resources,especially clathrates and stranded shale gas resources located in remote regions.Theoretically,the activation of CH_(4) and the selectivity to the CH_(3)OH product are challenging due to the extreme stability of CH_(4) and relatively high reactivity of CH_(3)OH.The state-of-the-art‘methane reforming-methanol synthesis’process adopts a two-step strategy to avoid the further reaction of CH_(3)OH under the harsh conditions required for CH_(4) activation.In the electrochemical field,researchers are trying to develop conversion pathways under mild conditions.They have found suitable catalysts to activate the C–H bonds in methane with the help of external charge and have designed the electrode reactions to continuously generate certain active oxygen species.These active oxygen species attack the activated methane and convert it to CH_(3)OH,with the benefit of avoiding over-oxidation of CH_(3)OH,and thus obtain a high conversion efficiency of CH_(4) to CH_(3)OH.This mini-review focuses on the advantages and challenges of electrochemical conversion of CH4 to CH_(3)OH,especially the strategies for supplying electro-generated active oxygen species in-situ to react with the activated methane.展开更多
Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice...Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.展开更多
The durability of reinforced concrete structures is greatly influenced by the corrosion of the reinforcement. In addition to air pollution related to the repair of corroded structures, chloride ions are the main facto...The durability of reinforced concrete structures is greatly influenced by the corrosion of the reinforcement. In addition to air pollution related to the repair of corroded structures, chloride ions are the main factors of corrosion of reinforced concrete structures. This study aims to valorize a clay inhibitor against reinforcement corrosion in reinforced concrete. This clay (Attapulgite) was incorporated into reinforced concretes at different percentages of substitution of calcined attapulgite (0%, 5% and 10%) to cement in the formulation. The corrosion inhibitory power of attapulgite is evaluated in reinforced concretes subjected to the action of chloride ions at different intervals in the NaCl solution (1 day, 21 days and 45 days) by electrochemical methods (zero current chronopotentiometry, polarization curves and electrochemical impedance spectroscopy). This study showed that in the presence of chloride ions, the composition based on 10% attapulgite has an appreciable inhibitory effect with an average inhibitory efficiency of 82%.展开更多
The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;h...The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.展开更多
Eu3+ is extracted at pH 6 with 5. 0×10-2 mol/L benzo-15-crown-5 in dichloromethane from 5. 0×10-2 mol/L aqueous solution of lithium picrate. The enriched extractability has been investigated. In a concentrat...Eu3+ is extracted at pH 6 with 5. 0×10-2 mol/L benzo-15-crown-5 in dichloromethane from 5. 0×10-2 mol/L aqueous solution of lithium picrate. The enriched extractability has been investigated. In a concentration range from 2. 4 ×10-4 to 1. 8 ×10-3 mol/L solution of europium nitrates, the enrichment coefficients are calculated with the phasc ratio (organic/aqueous) of 1: 5 or 4: 25. The ability of 0. 5 mol/L HNO3 as a back-extractant is discussed with the volume ratio [organic/(0. 5 mol/L HNO3)] of 1 : 3. Crown ether and picric acid exist in the back-extractivephase. Eu3+ is effectively separated from the organic phase by the electrochemical method. The separation efficiency is more than 84%. The optimum electrolysis time or cell voltage is obtained from the relation between the electrolysis current and the time or the voltage.展开更多
We discuss here essential aspects of the experimental supercapacitors characterization by a series of well-known electrochemical methods.We are motivated by a considerable number of publications that misreport procedu...We discuss here essential aspects of the experimental supercapacitors characterization by a series of well-known electrochemical methods.We are motivated by a considerable number of publications that misreport procedures and results.Authors often conceal or neglect essential information about the electrochemical analytical apparatus used and its configuration.The lack of such information may lead researchers,especially inexperienced ones,to misunderstand the procedures and results.Eventually,the misled electrochemical equipment configuration favors misinterpretation of data and low reproducibility rates.This paper aims to highlight these issues and clarify them.We explain fundamental concepts of some electrochemical analytical methods,such as cyclic voltammetry,galvanostatic charge-discharge,single potential step chronoamperometry,and electrochemical impedance spectroscopy,focusing on the supercapacitor field.Distinct configurations of electrical parameters are presented and discussed to highlight the effects of incorrect setup and uncover misleading results.We discuss how the electrochemical setup and data analyses matter in reliable data results for the supercapacitor.展开更多
Electrochemical chloride extraction is a promising technique for the rehabilitation of concrete structures under chloride induced corrosion. This study consists of an extensive literature review of this treatment incl...Electrochemical chloride extraction is a promising technique for the rehabilitation of concrete structures under chloride induced corrosion. This study consists of an extensive literature review of this treatment including application cases. It is found that the rate of chlorides removed is affected by the total charge passed, whereas increasing charge in a range between 1500 to 2000 Ah/m<sup>2</sup> increases the amount of chlorides removed and this can be more effective by increasing current density instead of duration of treatment. Bound chlorides are extracted during treatment and, water works better than Ca(OH)<sub>2</sub> as an electrolyte, possibly due to modifications on the concrete pore structure. Moreover, ECE is not efficient in repassivate structures but is efficient in its purpose of removing chlorides if treatment setup is well planned, which justifies the need for better international standards on the topic.展开更多
This work first investigates the corrosion-inhibiting behavior of montmorillonite K-10 on reinforcing steel. The corrosion-inhibiting power of the clay (Montmorillonite) is determined in a medium HCl (C = 1N) using fr...This work first investigates the corrosion-inhibiting behavior of montmorillonite K-10 on reinforcing steel. The corrosion-inhibiting power of the clay (Montmorillonite) is determined in a medium HCl (C = 1N) using free corrosion potential monitoring, Tafel potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results of this study showed a satisfactory corrosion-inhibiting efficiency of around 72.665% for the optimum content of 1%. This is due to the presence of a stable oxide layer that protects the metal against corrosion. To validate the concept of montmorillonite as a corrosion inhibitor in repair mortar, we now turn to the influence of montmorillonite on the mechanical properties of mortars in the hardened state. In this part, montmorillonite K-10 is added to the mortar by partial substitution of the cement by 5% and 10% of the cement mass. The aim of this study is to ensure that the addition of this clay to the mortar composition will not have a negative effect on its compressive and flexural strengths. The results of the compression and flexural tests showed that the presence of montmorillonite in the mortar improved flexural and compressive strengths for the different compositions studied.展开更多
Most reinforced concrete structures in seaside locations suffer from corrosion damage to the reinforcement, limiting their durability and necessitating costly repairs. To improve their performance and durability, we h...Most reinforced concrete structures in seaside locations suffer from corrosion damage to the reinforcement, limiting their durability and necessitating costly repairs. To improve their performance and durability, we have investigated in this paper Aloe vera extracts as a green corrosion inhibitor for reinforcing steel in NaCl environments. Using electrochemical methods (zero-intensity chronopotentiometry, Tafel lines and electrochemical impedance spectroscopy), this experimental work investigated the effect of these Aloe vera (AV) extracts on corrosion inhibition of concrete reinforcing bar (HA, diameter 12mm) immersed in a 0.5M NaCl solution. The results show that Aloe vera extracts have an average corrosion-inhibiting efficacy of around 86% at an optimum concentration of 20%.展开更多
Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducin...Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,' respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.展开更多
The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show ...The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show that both of the alloys have a typical single-phase hexagonal CaCus-type structure. The cell volume of the hylpo-stoichiometric alloy M1B4.85 is slightly larger than that of the stoichiometric alloy M1B5.0, although its lattice constant cla is smaller. Under 2 C discharging rate, i.e. 640 mA/g, the M1B4.85 has a discharge capacity of 320 mAh/g, which is higher than that of the M1Bs.o, 312 mAh/g. Nevertheless, the capacities of the M1B4.85 and the M1Bs.o decline 24.7% and 20.2% after 400 cycles, respectively. The relationship of electrochemical performances of the alloys with their structures is discussed.展开更多
The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with andwithout electroless plated Ni-P was investigated by electrochemical methods, in artificial Tyrode'ssolution. The results showed that Cu-Zn-...The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with andwithout electroless plated Ni-P was investigated by electrochemical methods, in artificial Tyrode'ssolution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode'ssolution. The anodic active current densities as well as electrochemical dissolution sensitivity ofthe electroless plated Ni-P Cu-Zn-Al SMA increased with NaCl concentration rising, pH of solutiondecreasing and environmental temperature uprising. X-ray diffraction analysis indicated that aftersurface modification by electroless plated Ni-P, an amorphous plated film formed on the surface ofCu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantlyimprove the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode's solution.展开更多
Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems a...Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems are essentially required due to lack of effective vaccine against dengue virus and the progressive spread of the dengue virus infection.The recent progress in developing micro-and nano-fabrication techniques has led to low cost and scale down the biomedical point-of-care devices.Starting from the conventional and modern available methods for the diagnosis of dengue infection,this review examines several emerging rapid and point-of-care diagnostic devices that hold significant potential for the progress in smart diagnosis tools.The given review revealed that an effective vaccine is required urgently against all the dengue virus serotypes.However,the rapid detection methods of dengue virus help in early treatment and significantly reduce the dengue virus outbreak.展开更多
The anode processes of carbon electrode in LiF-70%NdF3 melt were studied by electroanalytical techniques, including cyclic voltammetry(CV) and chronoamperometry(CA). Anode gases were analyzed by gas chromatography(GC)...The anode processes of carbon electrode in LiF-70%NdF3 melt were studied by electroanalytical techniques, including cyclic voltammetry(CV) and chronoamperometry(CA). Anode gases were analyzed by gas chromatography(GC) on-line during controlled-potential electrolysis. Two anode peaks were observed. The first process starting at 2.0 V vs Li+/Li was corresponded to the discharge of residual oxide ions, with the generation of CO and CO2. The discharge of fluoride ions occurred at the potentials higher than 4.3 V vs Li+/Li, with the generation of a small amount of CF4 and C2F6, accompanied by a sudden drop in current, marking the onset of the anode effect. The second process occurred when the potential exceeded 5.5 V vs Li+/Li, with the generation of a large amount of CF4 and C2F6. When the temperature was changed from 1173 to 1273 K, the current of the second process decreased, leading to a stable anode effect.展开更多
The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer's solution. The results showed that afte...The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer's solution. The results showed that after benzotriazole passivation, the corrosion resistance of the Cu-Zn-Al shape memory alloy was improved evidently. The anodic polarization current density of the passivated alloy decreased, the mass loss reduced, the anodic passivation accelerated, the anodic active dissolution was inhibited effectively, and the surface tarnishing was reswained. Infrared reflection spectrum test showed that Cu(Ⅰ)-benzotriazole or Cu(Ⅱ)-benzotriazole complex layer was formed on the surface of the Cu-Zn-Al shape memory alloy after passivation. This layer appeared plane, well adhesion, and presented homogeneous golden metallic luster. The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole is improved for the formation of an electrochemical stable baffle layer on passivated surface. This layer separates the metal substrate from the outside corrosion medium effectively and retards the corrosion process of dezincification.展开更多
Noble metallic nanocrystals are used in a wide variety of applications,such as catalysis,batteries,and bio-and chemical sensors.Most of the previous studies focus on the preparation of thermodynamically stable nanocry...Noble metallic nanocrystals are used in a wide variety of applications,such as catalysis,batteries,and bio-and chemical sensors.Most of the previous studies focus on the preparation of thermodynamically stable nanocrystals enclosed by low-index facets and discuss their corresponding catalytic properties.Recently,researchers have found that the nanocrystals with high-index facets(HIFs)are of more interest for electrocatalysis.Herein,we review recent key progress in the synthesis of noble metallic nanoparticles enclosed with HIFs and their facetdependent electrocatalytic behaviors.First,we introduce the concept of HIFs,and establish the correlation between their surface structure and catalytic activity.Then,we discuss various synthetic approaches for controlling the shapes and composition of the nanocrystals enclosed by HIFs.Afterwards,we showcase the enhanced electrocatalytic performance realized by HIF-based nanostructures.Finally,we provide guidance on how to improve the electrocatalysis by engineering HIFs on noble metallic nanocrystals.展开更多
The structures of the solar-thermal membranes always influence the performance of light absorption and salt resistance in desalination.Inspired by the hierarchical structure of the coniferous leaves with excellent sun...The structures of the solar-thermal membranes always influence the performance of light absorption and salt resistance in desalination.Inspired by the hierarchical structure of the coniferous leaves with excellent sunlight absorption in frigid regions,a coniferous leaf-like nickel black(L-Ni)membrane for desalination by solar-thermal energy conversion was prepared through electroplating method under a constant voltage.The light trapping effect of coniferous leaf-like structure led to the light absorption enhanced to 92%,the evaporation rate improved to 1.38 kg·m^(-2)·h^(-1),and the solar-vapor conversion efficiency of L-Ni membrane reaching up to 89.75%under 1 sun irradiation.The stability of the membrane was still excellent after 20 cycles desalination because the coniferous leaf-like structure could enhance the hydrophobicity(water contact angle:152°)of the L-Ni membrane,and it was beneficial to salt resistance.The promising performance of L-Ni membrane with coniferous leaf-like structure provides a possibility to replace the noble metal solar-thermal conversion materials.展开更多
文摘We proposed an empirical equation for a fine-structure constant: . Then, . where m<sub>p</sub> and m<sub>e</sub> are the rest mass of a proton and the rest mass of an electron, respectively. In this report, using the electrochemical method, we proposed an equivalent circuit. Then, we proposed a refined version of our own old empirical equations about the electromagnetic force and gravity. Regarding the factors of 9/2 and π, we used 3.132011447 and 4.488519503, respectively. The calculated values of T<sub>c</sub> and G are 2.726312 K and 6.673778 × 10<sup>-11</sup> (m<sup>3</sup>⋅kg<sup>-1</sup>⋅s<sup>-2</sup>).
文摘Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite has been synthesized through electrochemical method and characterized by UV-Visible spectroscopy, XRD, SEM and EDAX data. UV-Visible spectroscopy measurements reveal that the Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite has maximum absorption at 353.04 nm and this peak position reflects the band gap of particles and it is found to be 2.51 eV which was calculated using Tauc plot. X-Ray diffraction (XRD) reveals crystaline size to be 49.85 nm which was calculated using Williamson-Hall (W-H) plot method. Photocatalytic degradation of acetic acid, chloroacetic acid and trichloroacetic acid has been studied by volumetric method using NaOH solution. Photocatalytic degradation of chloroacetic acid and acetic acid follows first order kinetics. The photodegradation efficiency for Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite was found to be ≈97.8%. A Taft linear free energy relationship is noted for the catalysed reaction with ρ* = 0.233 and indicating electron withdrawing groups enhance the rate. An isokinetic relation is observed with β = 358 K indicating that enthalpy factor controls the reaction rate. The result of this paper suggests the possibility of degradation of organic compounds, industrial effluants and toxic organic compounds by photodegradation process by ecofriendly Al<sub>2</sub>S<sub>3</sub>/ MoS<sub>2</sub>. The antibacterial activity of Al<sub>2</sub>S<sub>3</sub>/MoS<sub>2</sub> nanocomposite was investigated. These particles were shown to have an effective bactericide.
基金supported by National Natural Science Foundation of China(Grant No.50864002)Guangxi Provincial Natural Science Foundation of China(Grant No.0991001)Natural Science Foundation of Guangxi University of China(Grant No.X071081)
文摘The existence of inclusion influences the properties of aluminum alloy castings,from which the castings will face scrapping under severe condition.Great efforts on the inclusions in aluminum alloy were made and many inclusion assessment methods were put forward.However,most of the current methods are characterized by time consuming and expensive equipment cost,which limits the application in aluminum industry.Since the aluminum properties are sensitive to the inclusion,this paper tries to establish a new kind of inclusion assessment method.The inclusions were introduced to aluminum melts by adding aluminum scraps.The samples with different inclusion contents were prepared.The microstructure contained inclusions was observed.The inclusion was automatically identified with an image analyzer by setting different grey threshold value,and the inclusion content was obtained.The image analysis shows that inclusions wreck the continuity of the alloy matrix seriously,and the inclusion area percentage increases with the increasing of aluminum scraps.The high and low polarization measurements were conducted in 3.5 wt% NaCl aqueous solution at the temperature of 25 ℃.The electrochemical parameters of the testing materials,such as corrosion potential E k,corrosion current density I k and the linear polarization resistance R p,were obtained.The polarization measurement results show that the linear polarization resistances decrease,the corrosion potentials move towards more negative direction,and the corrosion current densities increase with the increasing of inclusion content.The theoretical analysis of the inclusion content and the corrosion current density was performed.The existence of inclusions makes the microstructure form corrosion microcells between the alloy matrix and inclusions.The impressed current can accelerate the current velocity or corrosion current density.The regression model of the inclusion contents vs.the corrosion current density was obtained.This model can be used to quantitatively analyze the inclusion content in aluminum alloys on the basis of inclusion sensitivity to the inclusion content.It is confirmed that the electrochemical method for inclusion assessment (EcMIA) is simple and reliable,which can provide a new solution for inclusion assessment in aluminum alloy.
基金support from National Science Foundation of China(No.22075012).
文摘A convenient method for methane(CH_(4))direct conversion to methanol(CH_(3)OH)is of great significance to use methane-rich resources,especially clathrates and stranded shale gas resources located in remote regions.Theoretically,the activation of CH_(4) and the selectivity to the CH_(3)OH product are challenging due to the extreme stability of CH_(4) and relatively high reactivity of CH_(3)OH.The state-of-the-art‘methane reforming-methanol synthesis’process adopts a two-step strategy to avoid the further reaction of CH_(3)OH under the harsh conditions required for CH_(4) activation.In the electrochemical field,researchers are trying to develop conversion pathways under mild conditions.They have found suitable catalysts to activate the C–H bonds in methane with the help of external charge and have designed the electrode reactions to continuously generate certain active oxygen species.These active oxygen species attack the activated methane and convert it to CH_(3)OH,with the benefit of avoiding over-oxidation of CH_(3)OH,and thus obtain a high conversion efficiency of CH_(4) to CH_(3)OH.This mini-review focuses on the advantages and challenges of electrochemical conversion of CH4 to CH_(3)OH,especially the strategies for supplying electro-generated active oxygen species in-situ to react with the activated methane.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY12A01002)the National Natural Science Foundation of China(Grant Nos.11204058 and 21073162)the Hangzhou Dianzi University,China(Grant No.KYF09150603)
文摘Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.
文摘The durability of reinforced concrete structures is greatly influenced by the corrosion of the reinforcement. In addition to air pollution related to the repair of corroded structures, chloride ions are the main factors of corrosion of reinforced concrete structures. This study aims to valorize a clay inhibitor against reinforcement corrosion in reinforced concrete. This clay (Attapulgite) was incorporated into reinforced concretes at different percentages of substitution of calcined attapulgite (0%, 5% and 10%) to cement in the formulation. The corrosion inhibitory power of attapulgite is evaluated in reinforced concretes subjected to the action of chloride ions at different intervals in the NaCl solution (1 day, 21 days and 45 days) by electrochemical methods (zero current chronopotentiometry, polarization curves and electrochemical impedance spectroscopy). This study showed that in the presence of chloride ions, the composition based on 10% attapulgite has an appreciable inhibitory effect with an average inhibitory efficiency of 82%.
基金gratefully express their appreciation to National Natural Science Foundation of China(Nos.51974153 and U1960203)the Joint Fund of State Key Laboratory of Marine Engineering and University of Science and Technology Liaoning(SKLMEA-USTL-201707)the China Scholarship Council(201908210457).
文摘The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.
文摘Eu3+ is extracted at pH 6 with 5. 0×10-2 mol/L benzo-15-crown-5 in dichloromethane from 5. 0×10-2 mol/L aqueous solution of lithium picrate. The enriched extractability has been investigated. In a concentration range from 2. 4 ×10-4 to 1. 8 ×10-3 mol/L solution of europium nitrates, the enrichment coefficients are calculated with the phasc ratio (organic/aqueous) of 1: 5 or 4: 25. The ability of 0. 5 mol/L HNO3 as a back-extractant is discussed with the volume ratio [organic/(0. 5 mol/L HNO3)] of 1 : 3. Crown ether and picric acid exist in the back-extractivephase. Eu3+ is effectively separated from the organic phase by the electrochemical method. The separation efficiency is more than 84%. The optimum electrolysis time or cell voltage is obtained from the relation between the electrolysis current and the time or the voltage.
基金the financial support from the Brazilian funding agencies CNPq(310544/2019-0)FAPESP(2014/02163-7,2017/11958-1&2016/08645-9)+2 种基金FAPEMIG(Financial support for the LMMA/UFVJM Laboratory)CNPq(PQ-2 grant:Process 301095/2018-3)the support from Shell。
文摘We discuss here essential aspects of the experimental supercapacitors characterization by a series of well-known electrochemical methods.We are motivated by a considerable number of publications that misreport procedures and results.Authors often conceal or neglect essential information about the electrochemical analytical apparatus used and its configuration.The lack of such information may lead researchers,especially inexperienced ones,to misunderstand the procedures and results.Eventually,the misled electrochemical equipment configuration favors misinterpretation of data and low reproducibility rates.This paper aims to highlight these issues and clarify them.We explain fundamental concepts of some electrochemical analytical methods,such as cyclic voltammetry,galvanostatic charge-discharge,single potential step chronoamperometry,and electrochemical impedance spectroscopy,focusing on the supercapacitor field.Distinct configurations of electrical parameters are presented and discussed to highlight the effects of incorrect setup and uncover misleading results.We discuss how the electrochemical setup and data analyses matter in reliable data results for the supercapacitor.
文摘Electrochemical chloride extraction is a promising technique for the rehabilitation of concrete structures under chloride induced corrosion. This study consists of an extensive literature review of this treatment including application cases. It is found that the rate of chlorides removed is affected by the total charge passed, whereas increasing charge in a range between 1500 to 2000 Ah/m<sup>2</sup> increases the amount of chlorides removed and this can be more effective by increasing current density instead of duration of treatment. Bound chlorides are extracted during treatment and, water works better than Ca(OH)<sub>2</sub> as an electrolyte, possibly due to modifications on the concrete pore structure. Moreover, ECE is not efficient in repassivate structures but is efficient in its purpose of removing chlorides if treatment setup is well planned, which justifies the need for better international standards on the topic.
文摘This work first investigates the corrosion-inhibiting behavior of montmorillonite K-10 on reinforcing steel. The corrosion-inhibiting power of the clay (Montmorillonite) is determined in a medium HCl (C = 1N) using free corrosion potential monitoring, Tafel potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results of this study showed a satisfactory corrosion-inhibiting efficiency of around 72.665% for the optimum content of 1%. This is due to the presence of a stable oxide layer that protects the metal against corrosion. To validate the concept of montmorillonite as a corrosion inhibitor in repair mortar, we now turn to the influence of montmorillonite on the mechanical properties of mortars in the hardened state. In this part, montmorillonite K-10 is added to the mortar by partial substitution of the cement by 5% and 10% of the cement mass. The aim of this study is to ensure that the addition of this clay to the mortar composition will not have a negative effect on its compressive and flexural strengths. The results of the compression and flexural tests showed that the presence of montmorillonite in the mortar improved flexural and compressive strengths for the different compositions studied.
文摘Most reinforced concrete structures in seaside locations suffer from corrosion damage to the reinforcement, limiting their durability and necessitating costly repairs. To improve their performance and durability, we have investigated in this paper Aloe vera extracts as a green corrosion inhibitor for reinforcing steel in NaCl environments. Using electrochemical methods (zero-intensity chronopotentiometry, Tafel lines and electrochemical impedance spectroscopy), this experimental work investigated the effect of these Aloe vera (AV) extracts on corrosion inhibition of concrete reinforcing bar (HA, diameter 12mm) immersed in a 0.5M NaCl solution. The results show that Aloe vera extracts have an average corrosion-inhibiting efficacy of around 86% at an optimum concentration of 20%.
基金supported by the National Natural Science Foundation of China(No.21073111)the Natural Science Foundation of Shandong Province,China(No.ZR2010BQ029)
文摘Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuC14) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,' respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.
基金[This project was supported by the National Natural Science Foundation of China (No. 20373016), the Key Project of In-ternational Science and Technology Cooperation of MOST of China (No. 2005DFA60580), the Key Project of Guangdong Province (No. 2005B50101003), and the Excellent Young Teachers Program of MOE of China.]
文摘The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show that both of the alloys have a typical single-phase hexagonal CaCus-type structure. The cell volume of the hylpo-stoichiometric alloy M1B4.85 is slightly larger than that of the stoichiometric alloy M1B5.0, although its lattice constant cla is smaller. Under 2 C discharging rate, i.e. 640 mA/g, the M1B4.85 has a discharge capacity of 320 mAh/g, which is higher than that of the M1Bs.o, 312 mAh/g. Nevertheless, the capacities of the M1B4.85 and the M1Bs.o decline 24.7% and 20.2% after 400 cycles, respectively. The relationship of electrochemical performances of the alloys with their structures is discussed.
文摘The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with andwithout electroless plated Ni-P was investigated by electrochemical methods, in artificial Tyrode'ssolution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode'ssolution. The anodic active current densities as well as electrochemical dissolution sensitivity ofthe electroless plated Ni-P Cu-Zn-Al SMA increased with NaCl concentration rising, pH of solutiondecreasing and environmental temperature uprising. X-ray diffraction analysis indicated that aftersurface modification by electroless plated Ni-P, an amorphous plated film formed on the surface ofCu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantlyimprove the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode's solution.
基金supported by the Scientific Research Fund of the Shenzhen International cooperation projects under Grant Nos.(GJHZ20190819151403615)the Natural Science Youth Foundation of China(61801307).
文摘Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems are essentially required due to lack of effective vaccine against dengue virus and the progressive spread of the dengue virus infection.The recent progress in developing micro-and nano-fabrication techniques has led to low cost and scale down the biomedical point-of-care devices.Starting from the conventional and modern available methods for the diagnosis of dengue infection,this review examines several emerging rapid and point-of-care diagnostic devices that hold significant potential for the progress in smart diagnosis tools.The given review revealed that an effective vaccine is required urgently against all the dengue virus serotypes.However,the rapid detection methods of dengue virus help in early treatment and significantly reduce the dengue virus outbreak.
基金the National 973 Program (2007CB613301)the National Natural Science Foundation of China(50574012)
文摘The anode processes of carbon electrode in LiF-70%NdF3 melt were studied by electroanalytical techniques, including cyclic voltammetry(CV) and chronoamperometry(CA). Anode gases were analyzed by gas chromatography(GC) on-line during controlled-potential electrolysis. Two anode peaks were observed. The first process starting at 2.0 V vs Li+/Li was corresponded to the discharge of residual oxide ions, with the generation of CO and CO2. The discharge of fluoride ions occurred at the potentials higher than 4.3 V vs Li+/Li, with the generation of a small amount of CF4 and C2F6, accompanied by a sudden drop in current, marking the onset of the anode effect. The second process occurred when the potential exceeded 5.5 V vs Li+/Li, with the generation of a large amount of CF4 and C2F6. When the temperature was changed from 1173 to 1273 K, the current of the second process decreased, leading to a stable anode effect.
基金The project was financially supported by the State Key Laboratory for Corrosion and Protection of China.
文摘The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer's solution. The results showed that after benzotriazole passivation, the corrosion resistance of the Cu-Zn-Al shape memory alloy was improved evidently. The anodic polarization current density of the passivated alloy decreased, the mass loss reduced, the anodic passivation accelerated, the anodic active dissolution was inhibited effectively, and the surface tarnishing was reswained. Infrared reflection spectrum test showed that Cu(Ⅰ)-benzotriazole or Cu(Ⅱ)-benzotriazole complex layer was formed on the surface of the Cu-Zn-Al shape memory alloy after passivation. This layer appeared plane, well adhesion, and presented homogeneous golden metallic luster. The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole is improved for the formation of an electrochemical stable baffle layer on passivated surface. This layer separates the metal substrate from the outside corrosion medium effectively and retards the corrosion process of dezincification.
基金This work was financially supported by the Beijing Natural Science Foundation(JQ18005)the National Natural Science Foundation of China(NSFC)(No.51671003)+2 种基金National Basic Research Program of China(No.2016YFB0100201)the China Postdoctoral Science Foundation(No.2017M620518)Open Project Foundation of State Key Laboratory of Chemical Resource Engineering,the start-up supports from Peking University and Young Thousand Talented Program.
文摘Noble metallic nanocrystals are used in a wide variety of applications,such as catalysis,batteries,and bio-and chemical sensors.Most of the previous studies focus on the preparation of thermodynamically stable nanocrystals enclosed by low-index facets and discuss their corresponding catalytic properties.Recently,researchers have found that the nanocrystals with high-index facets(HIFs)are of more interest for electrocatalysis.Herein,we review recent key progress in the synthesis of noble metallic nanoparticles enclosed with HIFs and their facetdependent electrocatalytic behaviors.First,we introduce the concept of HIFs,and establish the correlation between their surface structure and catalytic activity.Then,we discuss various synthetic approaches for controlling the shapes and composition of the nanocrystals enclosed by HIFs.Afterwards,we showcase the enhanced electrocatalytic performance realized by HIF-based nanostructures.Finally,we provide guidance on how to improve the electrocatalysis by engineering HIFs on noble metallic nanocrystals.
基金The authors gratefully acknowledge the National Key R&D Program of China(Nos.2022YFB3903200 and 2022YFB3903203)the Natural Science Foundation of Jilin Province(No.20210101392JC).
文摘The structures of the solar-thermal membranes always influence the performance of light absorption and salt resistance in desalination.Inspired by the hierarchical structure of the coniferous leaves with excellent sunlight absorption in frigid regions,a coniferous leaf-like nickel black(L-Ni)membrane for desalination by solar-thermal energy conversion was prepared through electroplating method under a constant voltage.The light trapping effect of coniferous leaf-like structure led to the light absorption enhanced to 92%,the evaporation rate improved to 1.38 kg·m^(-2)·h^(-1),and the solar-vapor conversion efficiency of L-Ni membrane reaching up to 89.75%under 1 sun irradiation.The stability of the membrane was still excellent after 20 cycles desalination because the coniferous leaf-like structure could enhance the hydrophobicity(water contact angle:152°)of the L-Ni membrane,and it was beneficial to salt resistance.The promising performance of L-Ni membrane with coniferous leaf-like structure provides a possibility to replace the noble metal solar-thermal conversion materials.