The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,pred...The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,predicated on the assumption that the insertion/extraction of ions in the host materials is governed by diffusion.However,in practical scenarios,the electrochemical process might be dominated by interfacial reaction kinetics rather than diffusion.The present work derives analytical equations for electric current by considering the finite interfacial reaction kinetics and small overpotentials during PITT measurements and further studies the chemical stress field induced by the interfacial reaction-controlled ion insertion.The exchange current density(j_(0))can be ascertained using the analytical equation,which dictates the magnitude and decay rate of the electric current during a PITT process.The electric current decays more rapidly,and consequently,the lithium concentration reaches equilibrium faster for larger values of j_(0).The magnitude of the chemical stress is independent of j_(0) but depends on the overpotential.展开更多
A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode （DSPE） that was integrated with a portable smartphone-controlled ...A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode （DSPE） that was integrated with a portable smartphone-controlled potentiostat. The two carbon working channels of DSPE were first modified by electrodepositing of Prussian blue. The channels were then modified with acetylcholinesterase （ACHE） via Nation. The inhibition ratio of AChE was detected by comparing the electrical current of acetylthiocholine （ATCh） that was catalyzed by the enzyme electrodes with （channel 1） and without （channel 2） organophosphorus pesticide. Inhibition ratios were related with the negative logarithm of the organophosphorus pesticide （trichlorfon, oxamyl, and isocarbophos） concentrations at optimum experimental conditions （pH 6.9 of electrolyte, 0.2V working potential, 2.5μL AChE modification amount, and 15 min inhibition time）. The linear equations were 1%=32.301gC＋ 253.3 （R=0.9750） for isocarbophos, I% = 35.991gC＋ 270.1 （R = 0.9668） for chlorpyrifos, and 1% = 33.701gC＋ 250.5 （R = 0.9606） for trichlorfon. The detection limits were calculated as 10-7 g/mL. Given that the inhibition ratios were only related with pesticide concentration and not with pesticide species, the proposed electrodes and electrometer can rapidly detect universal organophosphorus pesticides and assess pesticide pollution.展开更多
A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential...A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential and convert the voltage for outPut; specific program runs in the PC to regulate and control the system. The effect of the proportion factor Kp on the control variation is researched through certain experiment. Two experiments, the control of electrolysis in constant poteniial and the determination of polarization curves, are designed to test and evaluate the effectiveness of the device. The experimemel results show that the variation between the actualanode potential and the target potential could be controlled to below 1 mV if Kp is set to an appropriate value.展开更多
This study aims to characterize the cavitation damage behavior of aluminum alloys in seawater and thus to enhance its cavitation resistance. Potentiostatic experiments were performed under various potential conditions...This study aims to characterize the cavitation damage behavior of aluminum alloys in seawater and thus to enhance its cavitation resistance. Potentiostatic experiments were performed under various potential conditions to determine the optimum protection potentials, at which cavitation damage was suppressed. A potential range was selected for the experiment from -2.2 to -1.4 V, which corresponded to the concentration and activation polarization regions on the cathodic polarization curve of the 5083-H116 alloy. After the experiments, the current density-time behavior was investigated, and the degree of surface damage was observed using three-dimensional microscopy and scanning electron microscopy （SEM）, The optimum protection potential was determined to be in the range of-l.9 to -1.5 V under which the cavitation damage was reduced significantly.展开更多
A low component count, microcontroller-based potentiostat circuit was developed through the use of operational amplifiers arranged in different feedback configurations. This was developed to alleviate the cost burden ...A low component count, microcontroller-based potentiostat circuit was developed through the use of operational amplifiers arranged in different feedback configurations. This was developed to alleviate the cost burden of equipment procurement in low-cost and budget applications. Simplicity was achieved in the design by the use of the microcontroller’s native functionalities and a low-cost R/2R resistor ladder digital-to-analogue converter. The potentiostat was used to investigate the Ni2+/Ni(s) redox couple in a 3-electrode cell with a silver/silver chloride reference electrode and graphite counter and working electrodes. Linear sweep voltammograms were ob-tained at scan rates of 10, 20, 30 and 40 mV/s. The analysis of the peak current versus (scan rate)1/2 plot indicated that the Ni2+/Ni(s) reduction, though conforming to the Randles-Sevcik equation, was a non-reversible redox reaction.展开更多
Designing transition metal nickel-cobalt-based battery-type electrode materials driven by anions is crucial for achieving rapid OH-ion transport under electrochemical activation conditions,thereby improving capacitanc...Designing transition metal nickel-cobalt-based battery-type electrode materials driven by anions is crucial for achieving rapid OH-ion transport under electrochemical activation conditions,thereby improving capacitance performance.Herein,borate anions are selected through theoretical calculations,and twodimensional(2D)defect-rich amorphous nickel-cobalt-based borate is synthesized via a facile chemical reduction method.Under potentiostatic modification,activated products(NCB-G-E)are obtained.In situ Raman spectra reveal that electron-deficient borate extracts electrons from metal centers,facilitating the oxidation state transition of Ni and Co.Theoretical calculations show that in situ adsorbed borate regulates the d-band centers of metal sites,enhancing OH^(-)intermediate adsorption.Meanwhile,borate anion adsorption accelerates the deprotonation and activation processes.Electrochemical tests demonstrate that NCB-G-E displays superior capacitance performance,with a high quality specific capacity of383.3 mA h g^(-1)and 65% retention rate at 30 A g^(-1),surpassing most nickel-cobalt-based electrodes.The assembled asymmetric supercapacitor presents an impressive energy density of 68.2 Wh kg^(-1)and good cycling stability.This work highlights the role of electron-deficient borate in tuning metal band structure and promoting oxidation state transition through synergistic defect advantages,offering new prospects for advanced battery-type energy storage materials.展开更多
In deaerated 0.05 M,0.1 M,0.2 M and 0.5 M K_(2)HPO_(4) solutions with pH 9.5,AZ31 magnesium(Mg)alloy was subjected to potentiostatic polarization at−0.8 VSCE to deposit a phosphate conversion coating.The morphology,st...In deaerated 0.05 M,0.1 M,0.2 M and 0.5 M K_(2)HPO_(4) solutions with pH 9.5,AZ31 magnesium(Mg)alloy was subjected to potentiostatic polarization at−0.8 VSCE to deposit a phosphate conversion coating.The morphology,structure,chemical composition,and protective performance of the conversion coating during the formation process were characterized.The results showed that amorphous Mg(OH)_(2) and MgHPO_(4) and crystallized KMgPO_(4)·6H2O(struvite-K)were successively deposited on the surface of AZ31 Mg alloy in the four solutions.MgHPO_(4) was converted from Mg(OH)_(2),while struvite-K was transformed from MgHPO_(4).The distribution of Mg(OH)_(2),MgHPO_(4) and struvite-K along the thickness of the coating difers with K_(2)HPO_(4) concentration.As the concentration of K_(2)HPO_(4) increased,the coating time was gradually shortened,and the coating was gradually thinned.Meanwhile,the ratio of the nucleation rate to the growth rate of struvite-K crystal nuclei increased,resulting in a decrease in the size of struvite-K crystal.When the concentration of K_(2)HPO_(4) increased from 0.05 to 0.1 M,the content of struvite-K increased,and the protective performance of the coating was enhanced.However,as the concentration of K_(2)HPO_(4) continued to increase to 0.5 M,the content of struvite-K and the protective performance of the coating decreased.展开更多
The coordination polymer poly（nickel-ethylenetetrathiolate） （poly（Ni-ett））, formed by nickel（Ⅱ） and 1,1,2,2-ethenetetrathiolate （ett）, is the most promising N-type organic thermoelectric material ever repor...The coordination polymer poly（nickel-ethylenetetrathiolate） （poly（Ni-ett））, formed by nickel（Ⅱ） and 1,1,2,2-ethenetetrathiolate （ett）, is the most promising N-type organic thermoelectric material ever reported; it is synthesized via potentiostatic deposition, and the effect of different applied potentials on the optimal performance of the polymers is investigated. The optimal thermoelectric property ofpoly（Ni-ett） synthesized at 0.6 V is remarkably greater than that of the polymers synthesized at 1 and 1.6 V, exhibiting a maximum power factor of up to 131.6μW/mK2 at 360 K. Furthermore, the structure-property correlation ofpoly（Ni-ett） is also extensively investigated. X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses revealed that the larger size of crystalline domains and the higher oxidation state of poly（Ni-ett） synthesized at 0.6 V possibly results in the higher bulk mobility and carrier concentration in the polymer chains, respectively, accounting for the enhanced power factor.展开更多
Electrochemical methods have been widely used in the chemical and pharmaceutical industries, which require accurate concentration measurements, chemical reaction detections and analyses. The electrochemical potentiost...Electrochemical methods have been widely used in the chemical and pharmaceutical industries, which require accurate concentration measurements, chemical reaction detections and analyses. The electrochemical potentiostat, the core element in electrochemical instruments, have been discussed as a hot topic addressing the difficulty of applying high-precision constant voltage and picoampere current measurements. Meanwhile, reliable potentiostats are in demand for complicated industrial environments with noises as well as requirements of remotemonitors. This paper describes a potentiostat for industrial glucose measurement that is not only accurate but also fault tolerant to guarantee high reliability in industrial environments. The instrument uses standard industrial communication protocols, proflbus, and a 4-20 mA current loop, for remote control and monitoring. Experimental results show that this design has 0.01% accuracy with 1 mV resolution for voltage applications and 0.01% accuracy with 1 pA resolution for current measurements. The design is also shown to be highly reliable in noisy environments.展开更多
The high-temperature requirement for liquid iron smelting via molten oxide electrolysis presents significant challenges.This study investigates the electrochemical reduction of Fe(Ⅲ)in a novel low-temperature electro...The high-temperature requirement for liquid iron smelting via molten oxide electrolysis presents significant challenges.This study investigates the electrochemical reduction of Fe(Ⅲ)in a novel low-temperature electrolyte,Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3),utilizing cyclic voltammetry and square wave voltammetry techniques.The results show that Fe(Ⅲ)reduction occurs in two steps:Fe(Ⅲ)+e^(−)→Fe(Ⅱ),Fe(Ⅱ)+2e^(−)→Fe,and that the redox process of Fe(Ⅲ)/Fe(Ⅱ)at the tungsten electrode is an irreversible reaction controlled by diffusion.The diffusion coefficients of Fe(Ⅲ)in the molten Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)in the temperature range of 1248–1278 K are between 1.86×10^(−6)cm^(2)/s and 1.58×10^(−4)cm^(2)/s.The diffusion activation energy of Fe(Ⅲ)in the molten salt is 1825.41 kJ/mol.As confirmed by XRD analysis,potentiostatic electrolysis at−0.857 V(vs.O_(2)/O_(complex)^(2-))for 6 h produces metallic iron on the cathode.展开更多
基金supported by the National Natural Science Foundation of China(No.12374003)the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515030256)the Shenzhen Science and Technology Program(Grant Nos.JCYJ20220531095208019 and GXWD20231129103124001).
文摘The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,predicated on the assumption that the insertion/extraction of ions in the host materials is governed by diffusion.However,in practical scenarios,the electrochemical process might be dominated by interfacial reaction kinetics rather than diffusion.The present work derives analytical equations for electric current by considering the finite interfacial reaction kinetics and small overpotentials during PITT measurements and further studies the chemical stress field induced by the interfacial reaction-controlled ion insertion.The exchange current density(j_(0))can be ascertained using the analytical equation,which dictates the magnitude and decay rate of the electric current during a PITT process.The electric current decays more rapidly,and consequently,the lithium concentration reaches equilibrium faster for larger values of j_(0).The magnitude of the chemical stress is independent of j_(0) but depends on the overpotential.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LQ17B050002)Analysis and Measurement Foundation of Zhejiang Province(No.2015C37068)
文摘A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode （DSPE） that was integrated with a portable smartphone-controlled potentiostat. The two carbon working channels of DSPE were first modified by electrodepositing of Prussian blue. The channels were then modified with acetylcholinesterase （ACHE） via Nation. The inhibition ratio of AChE was detected by comparing the electrical current of acetylthiocholine （ATCh） that was catalyzed by the enzyme electrodes with （channel 1） and without （channel 2） organophosphorus pesticide. Inhibition ratios were related with the negative logarithm of the organophosphorus pesticide （trichlorfon, oxamyl, and isocarbophos） concentrations at optimum experimental conditions （pH 6.9 of electrolyte, 0.2V working potential, 2.5μL AChE modification amount, and 15 min inhibition time）. The linear equations were 1%=32.301gC＋ 253.3 （R=0.9750） for isocarbophos, I% = 35.991gC＋ 270.1 （R = 0.9668） for chlorpyrifos, and 1% = 33.701gC＋ 250.5 （R = 0.9606） for trichlorfon. The detection limits were calculated as 10-7 g/mL. Given that the inhibition ratios were only related with pesticide concentration and not with pesticide species, the proposed electrodes and electrometer can rapidly detect universal organophosphorus pesticides and assess pesticide pollution.
文摘A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential and convert the voltage for outPut; specific program runs in the PC to regulate and control the system. The effect of the proportion factor Kp on the control variation is researched through certain experiment. Two experiments, the control of electrolysis in constant poteniial and the determination of polarization curves, are designed to test and evaluate the effectiveness of the device. The experimemel results show that the variation between the actualanode potential and the target potential could be controlled to below 1 mV if Kp is set to an appropriate value.
基金sponsored by the Cooperative Promotion Center of Science&Technology of Jeonnam Technopark and Ministry of Education,Science and Technology (MEST) through"The research&development support of Jeonnam southwest science park"
文摘This study aims to characterize the cavitation damage behavior of aluminum alloys in seawater and thus to enhance its cavitation resistance. Potentiostatic experiments were performed under various potential conditions to determine the optimum protection potentials, at which cavitation damage was suppressed. A potential range was selected for the experiment from -2.2 to -1.4 V, which corresponded to the concentration and activation polarization regions on the cathodic polarization curve of the 5083-H116 alloy. After the experiments, the current density-time behavior was investigated, and the degree of surface damage was observed using three-dimensional microscopy and scanning electron microscopy （SEM）, The optimum protection potential was determined to be in the range of-l.9 to -1.5 V under which the cavitation damage was reduced significantly.
文摘A low component count, microcontroller-based potentiostat circuit was developed through the use of operational amplifiers arranged in different feedback configurations. This was developed to alleviate the cost burden of equipment procurement in low-cost and budget applications. Simplicity was achieved in the design by the use of the microcontroller’s native functionalities and a low-cost R/2R resistor ladder digital-to-analogue converter. The potentiostat was used to investigate the Ni2+/Ni(s) redox couple in a 3-electrode cell with a silver/silver chloride reference electrode and graphite counter and working electrodes. Linear sweep voltammograms were ob-tained at scan rates of 10, 20, 30 and 40 mV/s. The analysis of the peak current versus (scan rate)1/2 plot indicated that the Ni2+/Ni(s) reduction, though conforming to the Randles-Sevcik equation, was a non-reversible redox reaction.
基金supported by the National Natural Science Foundation of China(22478422,22238012,and 22178384)Science Foundation of China University of Petroleum,Beijing(2462024QNXZ003)CHN Energy Investment Group(GJNY23-23)。
文摘Designing transition metal nickel-cobalt-based battery-type electrode materials driven by anions is crucial for achieving rapid OH-ion transport under electrochemical activation conditions,thereby improving capacitance performance.Herein,borate anions are selected through theoretical calculations,and twodimensional(2D)defect-rich amorphous nickel-cobalt-based borate is synthesized via a facile chemical reduction method.Under potentiostatic modification,activated products(NCB-G-E)are obtained.In situ Raman spectra reveal that electron-deficient borate extracts electrons from metal centers,facilitating the oxidation state transition of Ni and Co.Theoretical calculations show that in situ adsorbed borate regulates the d-band centers of metal sites,enhancing OH^(-)intermediate adsorption.Meanwhile,borate anion adsorption accelerates the deprotonation and activation processes.Electrochemical tests demonstrate that NCB-G-E displays superior capacitance performance,with a high quality specific capacity of383.3 mA h g^(-1)and 65% retention rate at 30 A g^(-1),surpassing most nickel-cobalt-based electrodes.The assembled asymmetric supercapacitor presents an impressive energy density of 68.2 Wh kg^(-1)and good cycling stability.This work highlights the role of electron-deficient borate in tuning metal band structure and promoting oxidation state transition through synergistic defect advantages,offering new prospects for advanced battery-type energy storage materials.
基金financially supported by the National Natural Science Foundation of China(No.52373322).
文摘In deaerated 0.05 M,0.1 M,0.2 M and 0.5 M K_(2)HPO_(4) solutions with pH 9.5,AZ31 magnesium(Mg)alloy was subjected to potentiostatic polarization at−0.8 VSCE to deposit a phosphate conversion coating.The morphology,structure,chemical composition,and protective performance of the conversion coating during the formation process were characterized.The results showed that amorphous Mg(OH)_(2) and MgHPO_(4) and crystallized KMgPO_(4)·6H2O(struvite-K)were successively deposited on the surface of AZ31 Mg alloy in the four solutions.MgHPO_(4) was converted from Mg(OH)_(2),while struvite-K was transformed from MgHPO_(4).The distribution of Mg(OH)_(2),MgHPO_(4) and struvite-K along the thickness of the coating difers with K_(2)HPO_(4) concentration.As the concentration of K_(2)HPO_(4) increased,the coating time was gradually shortened,and the coating was gradually thinned.Meanwhile,the ratio of the nucleation rate to the growth rate of struvite-K crystal nuclei increased,resulting in a decrease in the size of struvite-K crystal.When the concentration of K_(2)HPO_(4) increased from 0.05 to 0.1 M,the content of struvite-K increased,and the protective performance of the coating was enhanced.However,as the concentration of K_(2)HPO_(4) continued to increase to 0.5 M,the content of struvite-K and the protective performance of the coating decreased.
基金supported by the National Basic Research Program of China (2013CB632506)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12000000)+1 种基金Key Project of National Natural Science Foundation of China (51336009)National Natural Science Foundation of China (21290191, 21333011)
文摘The coordination polymer poly（nickel-ethylenetetrathiolate） （poly（Ni-ett））, formed by nickel（Ⅱ） and 1,1,2,2-ethenetetrathiolate （ett）, is the most promising N-type organic thermoelectric material ever reported; it is synthesized via potentiostatic deposition, and the effect of different applied potentials on the optimal performance of the polymers is investigated. The optimal thermoelectric property ofpoly（Ni-ett） synthesized at 0.6 V is remarkably greater than that of the polymers synthesized at 1 and 1.6 V, exhibiting a maximum power factor of up to 131.6μW/mK2 at 360 K. Furthermore, the structure-property correlation ofpoly（Ni-ett） is also extensively investigated. X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses revealed that the larger size of crystalline domains and the higher oxidation state of poly（Ni-ett） synthesized at 0.6 V possibly results in the higher bulk mobility and carrier concentration in the polymer chains, respectively, accounting for the enhanced power factor.
文摘Electrochemical methods have been widely used in the chemical and pharmaceutical industries, which require accurate concentration measurements, chemical reaction detections and analyses. The electrochemical potentiostat, the core element in electrochemical instruments, have been discussed as a hot topic addressing the difficulty of applying high-precision constant voltage and picoampere current measurements. Meanwhile, reliable potentiostats are in demand for complicated industrial environments with noises as well as requirements of remotemonitors. This paper describes a potentiostat for industrial glucose measurement that is not only accurate but also fault tolerant to guarantee high reliability in industrial environments. The instrument uses standard industrial communication protocols, proflbus, and a 4-20 mA current loop, for remote control and monitoring. Experimental results show that this design has 0.01% accuracy with 1 mV resolution for voltage applications and 0.01% accuracy with 1 pA resolution for current measurements. The design is also shown to be highly reliable in noisy environments.
基金Project(52074084)supported by the National Natural Science Foundation of China。
文摘The high-temperature requirement for liquid iron smelting via molten oxide electrolysis presents significant challenges.This study investigates the electrochemical reduction of Fe(Ⅲ)in a novel low-temperature electrolyte,Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3),utilizing cyclic voltammetry and square wave voltammetry techniques.The results show that Fe(Ⅲ)reduction occurs in two steps:Fe(Ⅲ)+e^(−)→Fe(Ⅱ),Fe(Ⅱ)+2e^(−)→Fe,and that the redox process of Fe(Ⅲ)/Fe(Ⅱ)at the tungsten electrode is an irreversible reaction controlled by diffusion.The diffusion coefficients of Fe(Ⅲ)in the molten Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)in the temperature range of 1248–1278 K are between 1.86×10^(−6)cm^(2)/s and 1.58×10^(−4)cm^(2)/s.The diffusion activation energy of Fe(Ⅲ)in the molten salt is 1825.41 kJ/mol.As confirmed by XRD analysis,potentiostatic electrolysis at−0.857 V(vs.O_(2)/O_(complex)^(2-))for 6 h produces metallic iron on the cathode.
