Nano-gold (NG) modified glassy carbon electrodes (GCEs) were used for determination of epinephrine (EP) in the presence of high concentration ascorbic acid (AA) by cyclic voltammetry (CV). This modified electrode can...Nano-gold (NG) modified glassy carbon electrodes (GCEs) were used for determination of epinephrine (EP) in the presence of high concentration ascorbic acid (AA) by cyclic voltammetry (CV). This modified electrode can not only catalytically oxidize EP and AA, but also separate the catalytic peak potentials of EP and AA by about 183.5 mV. In pH = 7.0 ogisogate byffer solution, the linear range of epinephrine was 5 106 ~ 1 ?10-4 mol/L.展开更多
A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs ...A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseo- dymium oxide was successfully doped into the SnOz-Sb film by CV method. Due to the doped Pr, the oxygen evo- lution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct/C0（φ） was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.展开更多
Microwave radiation was applied to the detection of metamizole sodium by cyclic voltammetry. The electrochemical characteristics of metamizole sodium were studied by cyclic voltammetry at GC electrode under microwave ...Microwave radiation was applied to the detection of metamizole sodium by cyclic voltammetry. The electrochemical characteristics of metamizole sodium were studied by cyclic voltammetry at GC electrode under microwave radiation and a considerable current enhancement was observed for metamizole sodium in aqueous 0.05 mol/L H2SO4. Under the optional conditions, metamizole sodium was determined in the absence and presence of microwave activation. In the absence of microwave activation cyclic voltammogram of metamizole sodium shows good linear relationship in a concentration range of 8.0×10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 6.75× 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=12.973c-0.1905（R^2=0.9996, n=6）; in the presence of 80 W microwave activation cyclic voltammogram of metamizole sodiumin shows good linear relationship in a concentration range of 4.0× 10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 4,41 × 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=25.107c-0.1193（R^2=0.9973, n=7）. The current in the presence of 80 W microwave activation increases to about 2 orders of magnitude compared with that in the absence of microwave activation. The proposed method in the presence of microwave activation showed high selectivity and sensitivity, and the sampling of the disposal method is simple. The method was verified by the determination of Metamizole Sodium tablet with satisfactory results.展开更多
Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry i...Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry is applied and the overall performance of the active material is considerably enhanced.We discover that this treatment triggers the formation of Ni-Co-Cu ternary composite and optimizes the crystal structure of the untreated counterpart.The areal capacitance of the treated sample rockets up to 6.13 F cm^(-2)at 2 m A cm^(-2),almost 13 times higher than the untreated ones.Besides,the resistance is substantially reduced by cyclic voltammetry treatment.Moreover,the Coulombic efficiency and stability are concurrently elevated.The reasons behind this treatment are mulled over and reasonable hypothesis is suggested.This study provides a cheap and effortless way to reform the structures of as-obtained samples as well as vigorously raise the performance of current available materials.展开更多
To monitor the reaction between Ce^(4+) ion and Cl-ion at the electron level,an electrochemical experiment was designed in this work.Herein,the intermediate and final products that may be produced during the redox rea...To monitor the reaction between Ce^(4+) ion and Cl-ion at the electron level,an electrochemical experiment was designed in this work.Herein,the intermediate and final products that may be produced during the redox reaction are directly tracked by using cyclic voltammetry,and the influences of Ce^(4+) ion concentration,temperatu re and F-ion on the reduction peak potential of Ce^(4+) ion were investigated.The results show that Ce^(4+) ion reacts with Cl-ion through an irreversible reaction without any intermediate products,and the rate-determining step of the reaction is diffusion during the electrode reaction.The effects of temperature(20-40℃) and Ce^(4+) ion concentration(0.04-0.12 mol/L) on the reduction peak pote ntial of Ce^(4+) ion can be ignored,but the higher the molar ratio of F-to Ce^(4+)(0-3 mol/mol),the mo re easily the reduction of Ce^(4+) ion to Ce^(3+) ion occurs.Additionally,the Ce^(4+) ions are preferentially reduced by thiourea when thiourea is added in the HCl solution,and thiourea inhibits the oxidation of Cl-ions to Cl_(2) by forming a complex with Cl-ions.This work provides a theoretical basis for the role of thiourea in inhibiting Cl_(2) production and offers a new way to find new reductants.展开更多
Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show thatthere are no structUral defects exposed dire...Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show thatthere are no structUral defects exposed directly to the redox couple in solution, but EISexperiments indicate that collapsed sites exist in the monolayer. A method to estimate the degree ofdisorder in the Au/thiol monolayer surface is proposed by using admittance plane plot.展开更多
Superoxide ion was generated by the electrochemical reduction of oxygen at a platinum electrode in dimethylsulphoxide (DMSO). This work was focused on the nucleophilicity and scavenge of electrogenerated\|superoxide ...Superoxide ion was generated by the electrochemical reduction of oxygen at a platinum electrode in dimethylsulphoxide (DMSO). This work was focused on the nucleophilicity and scavenge of electrogenerated\|superoxide ion by cyclic voltammetry. The nucleophilic displacement reactions of superoxide ion with ethyl acetate and diethyl adipate were discussed and the reason for remarkable influence of diethyl adipate was elucidated. The scavenging activity of ascorbic acid was evaluated and the result allowed the conclusion that the scavenging ability of ascorbic acid is much lower in DMSO than in aqueous phase. UV\|spectrum of electrogenerated superoxide ion in DMSO exhibited a single absorption band with λ max at 275 nm, which certified further that the method of electrogeneration was reliable and superoxide ion was stable in DMSO.展开更多
Polymer capable of specific binding to Cu-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu-dipyridyl complex) was investigated by cyclic vo...Polymer capable of specific binding to Cu-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu-dipyridyl complex) was investigated by cyclic voltametric scanning using the carbon paste electrode modified by polymer particles in phosphate buffer solution. Factors that influence rebinding of the imprinted polymer were explored. The result demonstrated that the cyclic voltammetry was an efficient approach to explore interactions between template and imprinted polymers.展开更多
Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene actin...Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene acting as the test system. Compared with the traditional cyclic voltammetry utilizing symmetrical triangular waveform as the excitation one, the new method allows a simpler approach to mechanistic analysis of ultrafast chemical reactions coupled with a charge transfer. And perhaps more important, it also provides a way to eliminate the interference of the adsorbed product in dynamic monitoring. 2007 Zhi Yong Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of con...This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.展开更多
Manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel cells.Mn(Ⅲ) ions with e_(g) electron filling of-1 are the active sites for manganese-based electrocatalysts.However...Manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel cells.Mn(Ⅲ) ions with e_(g) electron filling of-1 are the active sites for manganese-based electrocatalysts.However,Mn(Ⅲ) sites may be disproportionated during electrochemical reactions,thus reducing the number of Mn(Ⅲ) active sites and decreasing the catalytic activity of manganese oxides.In this work,we developed a facile cyclic voltammetry method to monitor the evolution of Mn(Ⅲ) sites on a series of manganese oxides under "working" conditions.We proposed a descriptor S_(Mn(Ⅲ)) to describe the stability of Mn(Ⅲ).Our simulated and experimental results show that the higher is S_(Mn(Ⅲ)),the higher the active Mn(Ⅲ)density,and the higher the electrocatalytic activity of the manganese oxide electrocatalyst.展开更多
Cyclic voltammetry based on an electrochemical technique is one of the current methods that measure the developments of the electrochemical properties in biomaterial samples under conditions. Biomaterial structure was...Cyclic voltammetry based on an electrochemical technique is one of the current methods that measure the developments of the electrochemical properties in biomaterial samples under conditions. Biomaterial structure was changed by conductive material while these materials caused a connective network in whole of them and was able to transfer electrons inside of biomaterials. These changes in physical and chemical properties are investigated by analysis tools such as cyclic voltammetry (CV), X-radiation (XRF) and Ultraviolet-visible spectroscopy (UV-Vis). Bacterial cellulose is biodegradable, biosynthesis of A. xylinum which is a three-dimensional nano-network structure with a distinct tunnel and pore structure. In this study, the composite process produced electrically conducting bacterial cellulose pellicles containing well-dispersed and embedded multi-walled carbon nanotubes (MWCNTs) Ionic liquids (ILs), as observed in cyclic voltammetry (CV). For this purpose, we used a special tool, called OriginLab which is an industry-leading scientific graphing and data analysis software. The cyclic voltammetry graph presents the behavior of this composite which consists of a relationship between CNT dispersion, conductivity rate and changes in bacterial cellulose structure. The electrical conductivity of the cellulose/MWCNT composite was found different with respect to CNT dispersion. It was found that the incorporation process was a useful method not only for dispersing MWCNTs-ILs in an ultrafine fibrous network structure, but also for enhancing the electrical conductivity of the polymeric membranes.展开更多
Stevia crystal can be defined as a botanical herb that has good properties to use as a substitute for sugar.The electrochemical study has been utilized for the purpose of calculating the limited dosage of the safety t...Stevia crystal can be defined as a botanical herb that has good properties to use as a substitute for sugar.The electrochemical study has been utilized for the purpose of calculating the limited dosage of the safety that should be used in black tea by cyclic voltammetry(CV)technique using the nanosensor as a more effective glassy carbon electrode(GCE)and carbon nanotubes(CNTs).Stevia’s oxidation current peak has been 400 mV at 0.40 mmol/L concentration(i.e.28 mg/mL),and reduction current peaks at 600 and–600 mV.It leads to the conclusion that stevia is a limited concentration antioxidant component safe for use in black tea.Additionally,electro-chemical characteristics of the stevia compound in the black tea have been investigated at alkaline and acidic pH in order to give oxidizing behaviors in the alkaline medium,while in an acidic medium as an antioxidant agent in black tea.Other chemical properties such as different scan rates,reliability,and stability have also been investigated.展开更多
The interaction between DNA and the Eu(Phe) 3+ 3 complex ion has been studied by means of cyclic voltammetry and differential UV spectroscopy The results depicted an obvious decrease of peak current in CV plot...The interaction between DNA and the Eu(Phe) 3+ 3 complex ion has been studied by means of cyclic voltammetry and differential UV spectroscopy The results depicted an obvious decrease of peak current in CV plot after the reaction between the two species studied The observed peak potential separation was increased but the diffusion coefficient of Eu complex ion was decreased Hypochromicity was observed at 226 and 258 nm after the predicted interaction of them A preliminary interpretation is proposed for discussion展开更多
The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The r...The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The response of dopamine on imprinted electrode was much higher than that of other molecules, because of the existing of micro-cavities in polymeric film fitting with the size and shape of dopamine in the imprinted polymer. Experimental results showed that dopamine can be enriched by the imprinted film, therefore increasing the sensitivity of the sensor. The imprinted film could also efface the interference of ascorbic acid, indicating that dopamine can be determined with a large excess of ascorbic acid.展开更多
Saffron in aqueous solution was studied via electrochemical analysis with KCl as a supporting electrolyte using cyclic voltammetric technique to determine the redox current peaks at different concentration,pH and scan...Saffron in aqueous solution was studied via electrochemical analysis with KCl as a supporting electrolyte using cyclic voltammetric technique to determine the redox current peaks at different concentration,pH and scan rate(SR).It was found that an oxidation current peak appeared at potential+268 mV and two reduction current peaks at−282 and−850 mV.The oxidation current peak of saffron disappeared in alkaline medium at pH=12.An enhancement was observed in acidic medium at pH=6.Based on Randel equations and by using different scan rates,the diffusion coefficient(D_(f))for oxidation-reduction current peaks of saffron in KCl solution was determined with nearly equal values as of 1.87×10^(−5) and 1.12×10^(−5) cm^(2)/s,respectively.The results indicate a low detection limit of the different concentrations of saffron in KCl solution as determined from the calibration graph,and a high reliability revealed by the relative standard deviation(RSD).Stability of the GCE for oxidationreduction current peaks was recorded as±7.12%and±1.04%,respectively.展开更多
Cardamom oil is one of the active herbs used as a treatment in different diseases by the function of the blood serum components.Among the methods used for identification of function group which acted in the human body...Cardamom oil is one of the active herbs used as a treatment in different diseases by the function of the blood serum components.Among the methods used for identification of function group which acted in the human body,the method of electrochemical analysis using cyclic voltammetry was used to determine the effectiveness of cardamom by the oxidation-reduction reaction in the blood medium.Results showed that the cardamom compound presented peaks of oxidation-reduction in the blood serum medium of 0.8 and-0.65 V,respectively.The oxidation peak disappeared in alkaline pH;hence,the cardamom acted as anti-oxidative compound in alkaline medium and with ascorbic acid.But the oxidation peak was enhanced in acidic pH.Other electrochemical parameters of cardamom in blood serum medium were determined,including studies on different scan rates,reliability and stability.展开更多
A new modified ion selective electrode with carbon and metal oxide nanoparticles to increase sensitivity and selectivity to measure the trace concentration of heavy elements in solutions and pharmaceutical compounds.b...A new modified ion selective electrode with carbon and metal oxide nanoparticles to increase sensitivity and selectivity to measure the trace concentration of heavy elements in solutions and pharmaceutical compounds.by preparing the Nano-oxides of ZnO,CuO and MnO_(2) using a hydrothermal method.The temperature and pH of the electrode studied to select the best conditions.Where the voltmogram recorded a single signal in relation to the oxidation and reduction process of the zinc element by a reversable mechanism rever to one electron transmission and a quasi-reversable signal for the copper element,and irreversible signal for the manganese element resulting from the transmission of two electrons.The thermodynamic and kinetic factors were also studied and finally the standard mixture of the elements salt was detection to electrode sensitivity mutation the result show the new electrode can distinguish between the signals produced by the oxidation and reduction process of the three elements as the same time with three deferent peaks for oxidation and two peaks of redaction.展开更多
A new modified working electrode of glassy carbon electrode with nanoparticles of SiO_(2)(SiO_(2) nanoparticles/GCE)was prepared by mechanical attachment method.The modified electrode(SiO_(2) nanoparticles/GCE)was cha...A new modified working electrode of glassy carbon electrode with nanoparticles of SiO_(2)(SiO_(2) nanoparticles/GCE)was prepared by mechanical attachment method.The modified electrode(SiO_(2) nanoparticles/GCE)was characterised by electrochemical analysis using cyclic voltammetric technique to evaluate this electrode as nano-sensor.A standard solution of 1 mM K_(4)[Fe(CN)_(6)]with 1 M KCl as an electrolyte was used to study the redox current peaks of FeⅡ/FeⅢ ions on the modified electrode at different concentrations,scan rates,pH,determination of diffusion coefficient(Df),reliability and stability of the modified electrode.It was found the new nano-sensor(SiO_(2) nanoparticles/GCE)had enhancement for the oxidation and reduction current peak of FeII/FeIII ions of about 1.29 and 1.58µA,respectively.The current ration value of the new modified electrode was I_(pa)/I_(pc)=1.7 with the peak separation of ∆Epa-c=140 mV,which demonstrated that the new modified electrode acted in electrolyte as irreversible and heterogeneous reaction,had low detection limit,and enhanced the redox current peaks in acidic pH with good reliability and stability of nanoparticles on the surface of GCE.展开更多
基金The authors gratefully acknowledge financial support from the Natural Science Foundation of Anhui Province and the Natural Science Foundation of Anhui Education Committee.
文摘Nano-gold (NG) modified glassy carbon electrodes (GCEs) were used for determination of epinephrine (EP) in the presence of high concentration ascorbic acid (AA) by cyclic voltammetry (CV). This modified electrode can not only catalytically oxidize EP and AA, but also separate the catalytic peak potentials of EP and AA by about 183.5 mV. In pH = 7.0 ogisogate byffer solution, the linear range of epinephrine was 5 106 ~ 1 ?10-4 mol/L.
基金Supported by the National Natural Science Foundation of China(No.20706041)the Natural Science Foundation of Tianjin(No.09JCYBJC06500)
文摘A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseo- dymium oxide was successfully doped into the SnOz-Sb film by CV method. Due to the doped Pr, the oxygen evo- lution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct/C0（φ） was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.
基金Supported by the National Natural Science Foundation of China(No.20665001)the Natural Science Foundation of Guangxi Province,China(No.0832062)
文摘Microwave radiation was applied to the detection of metamizole sodium by cyclic voltammetry. The electrochemical characteristics of metamizole sodium were studied by cyclic voltammetry at GC electrode under microwave radiation and a considerable current enhancement was observed for metamizole sodium in aqueous 0.05 mol/L H2SO4. Under the optional conditions, metamizole sodium was determined in the absence and presence of microwave activation. In the absence of microwave activation cyclic voltammogram of metamizole sodium shows good linear relationship in a concentration range of 8.0×10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 6.75× 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=12.973c-0.1905（R^2=0.9996, n=6）; in the presence of 80 W microwave activation cyclic voltammogram of metamizole sodiumin shows good linear relationship in a concentration range of 4.0× 10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 4,41 × 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=25.107c-0.1193（R^2=0.9973, n=7）. The current in the presence of 80 W microwave activation increases to about 2 orders of magnitude compared with that in the absence of microwave activation. The proposed method in the presence of microwave activation showed high selectivity and sensitivity, and the sampling of the disposal method is simple. The method was verified by the determination of Metamizole Sodium tablet with satisfactory results.
基金the National Natural Science Foundation of China(Nos.21801200,21871217,U1905215 and 51872220)the Fundamental Research Funds for the Central Universities(Nos.WUT:2019IVB050,182459018 and 195201044)the Project of Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah,Saudi Arabia(No.FP-179-42)。
文摘Poor conductivity and rate capability are the obstacles faced by nickel-cobalt composites as electrode materials for supercapacitor application.Herein,simple electrochemical treatment conducted by cyclic voltammetry is applied and the overall performance of the active material is considerably enhanced.We discover that this treatment triggers the formation of Ni-Co-Cu ternary composite and optimizes the crystal structure of the untreated counterpart.The areal capacitance of the treated sample rockets up to 6.13 F cm^(-2)at 2 m A cm^(-2),almost 13 times higher than the untreated ones.Besides,the resistance is substantially reduced by cyclic voltammetry treatment.Moreover,the Coulombic efficiency and stability are concurrently elevated.The reasons behind this treatment are mulled over and reasonable hypothesis is suggested.This study provides a cheap and effortless way to reform the structures of as-obtained samples as well as vigorously raise the performance of current available materials.
基金Project supported by the National Key Research and Development Program of China (2020YFC1909104)Science and Technology Major Project of Guangxi (Guike AA18242022)+1 种基金Hebei Province Key Research and Development Plan Project (20374104D)。
文摘To monitor the reaction between Ce^(4+) ion and Cl-ion at the electron level,an electrochemical experiment was designed in this work.Herein,the intermediate and final products that may be produced during the redox reaction are directly tracked by using cyclic voltammetry,and the influences of Ce^(4+) ion concentration,temperatu re and F-ion on the reduction peak potential of Ce^(4+) ion were investigated.The results show that Ce^(4+) ion reacts with Cl-ion through an irreversible reaction without any intermediate products,and the rate-determining step of the reaction is diffusion during the electrode reaction.The effects of temperature(20-40℃) and Ce^(4+) ion concentration(0.04-0.12 mol/L) on the reduction peak pote ntial of Ce^(4+) ion can be ignored,but the higher the molar ratio of F-to Ce^(4+)(0-3 mol/mol),the mo re easily the reduction of Ce^(4+) ion to Ce^(3+) ion occurs.Additionally,the Ce^(4+) ions are preferentially reduced by thiourea when thiourea is added in the HCl solution,and thiourea inhibits the oxidation of Cl-ions to Cl_(2) by forming a complex with Cl-ions.This work provides a theoretical basis for the role of thiourea in inhibiting Cl_(2) production and offers a new way to find new reductants.
文摘Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show thatthere are no structUral defects exposed directly to the redox couple in solution, but EISexperiments indicate that collapsed sites exist in the monolayer. A method to estimate the degree ofdisorder in the Au/thiol monolayer surface is proposed by using admittance plane plot.
文摘Superoxide ion was generated by the electrochemical reduction of oxygen at a platinum electrode in dimethylsulphoxide (DMSO). This work was focused on the nucleophilicity and scavenge of electrogenerated\|superoxide ion by cyclic voltammetry. The nucleophilic displacement reactions of superoxide ion with ethyl acetate and diethyl adipate were discussed and the reason for remarkable influence of diethyl adipate was elucidated. The scavenging activity of ascorbic acid was evaluated and the result allowed the conclusion that the scavenging ability of ascorbic acid is much lower in DMSO than in aqueous phase. UV\|spectrum of electrogenerated superoxide ion in DMSO exhibited a single absorption band with λ max at 275 nm, which certified further that the method of electrogeneration was reliable and superoxide ion was stable in DMSO.
基金supported by the National Nalural Science Foundation of China(29975001)
文摘Polymer capable of specific binding to Cu-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu-dipyridyl complex) was investigated by cyclic voltametric scanning using the carbon paste electrode modified by polymer particles in phosphate buffer solution. Factors that influence rebinding of the imprinted polymer were explored. The result demonstrated that the cyclic voltammetry was an efficient approach to explore interactions between template and imprinted polymers.
基金We are grateful to the National Natural Science Foundation of China （No. 20173054）；the Natural Science Foundation of Ningbo City （No. 2006A610044）.
文摘Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene acting as the test system. Compared with the traditional cyclic voltammetry utilizing symmetrical triangular waveform as the excitation one, the new method allows a simpler approach to mechanistic analysis of ultrafast chemical reactions coupled with a charge transfer. And perhaps more important, it also provides a way to eliminate the interference of the adsorbed product in dynamic monitoring. 2007 Zhi Yong Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.
基金supported by the National Natu-ral Science Foundation of China(Nos.52071231,51722103)the Natural Science Foundation of Tianjin(19JCJQJC61900).
文摘Manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel cells.Mn(Ⅲ) ions with e_(g) electron filling of-1 are the active sites for manganese-based electrocatalysts.However,Mn(Ⅲ) sites may be disproportionated during electrochemical reactions,thus reducing the number of Mn(Ⅲ) active sites and decreasing the catalytic activity of manganese oxides.In this work,we developed a facile cyclic voltammetry method to monitor the evolution of Mn(Ⅲ) sites on a series of manganese oxides under "working" conditions.We proposed a descriptor S_(Mn(Ⅲ)) to describe the stability of Mn(Ⅲ).Our simulated and experimental results show that the higher is S_(Mn(Ⅲ)),the higher the active Mn(Ⅲ)density,and the higher the electrocatalytic activity of the manganese oxide electrocatalyst.
文摘Cyclic voltammetry based on an electrochemical technique is one of the current methods that measure the developments of the electrochemical properties in biomaterial samples under conditions. Biomaterial structure was changed by conductive material while these materials caused a connective network in whole of them and was able to transfer electrons inside of biomaterials. These changes in physical and chemical properties are investigated by analysis tools such as cyclic voltammetry (CV), X-radiation (XRF) and Ultraviolet-visible spectroscopy (UV-Vis). Bacterial cellulose is biodegradable, biosynthesis of A. xylinum which is a three-dimensional nano-network structure with a distinct tunnel and pore structure. In this study, the composite process produced electrically conducting bacterial cellulose pellicles containing well-dispersed and embedded multi-walled carbon nanotubes (MWCNTs) Ionic liquids (ILs), as observed in cyclic voltammetry (CV). For this purpose, we used a special tool, called OriginLab which is an industry-leading scientific graphing and data analysis software. The cyclic voltammetry graph presents the behavior of this composite which consists of a relationship between CNT dispersion, conductivity rate and changes in bacterial cellulose structure. The electrical conductivity of the cellulose/MWCNT composite was found different with respect to CNT dispersion. It was found that the incorporation process was a useful method not only for dispersing MWCNTs-ILs in an ultrafine fibrous network structure, but also for enhancing the electrical conductivity of the polymeric membranes.
文摘Stevia crystal can be defined as a botanical herb that has good properties to use as a substitute for sugar.The electrochemical study has been utilized for the purpose of calculating the limited dosage of the safety that should be used in black tea by cyclic voltammetry(CV)technique using the nanosensor as a more effective glassy carbon electrode(GCE)and carbon nanotubes(CNTs).Stevia’s oxidation current peak has been 400 mV at 0.40 mmol/L concentration(i.e.28 mg/mL),and reduction current peaks at 600 and–600 mV.It leads to the conclusion that stevia is a limited concentration antioxidant component safe for use in black tea.Additionally,electro-chemical characteristics of the stevia compound in the black tea have been investigated at alkaline and acidic pH in order to give oxidizing behaviors in the alkaline medium,while in an acidic medium as an antioxidant agent in black tea.Other chemical properties such as different scan rates,reliability,and stability have also been investigated.
文摘The interaction between DNA and the Eu(Phe) 3+ 3 complex ion has been studied by means of cyclic voltammetry and differential UV spectroscopy The results depicted an obvious decrease of peak current in CV plot after the reaction between the two species studied The observed peak potential separation was increased but the diffusion coefficient of Eu complex ion was decreased Hypochromicity was observed at 226 and 258 nm after the predicted interaction of them A preliminary interpretation is proposed for discussion
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 175 0 0 9) ,theDoctoralFoundationofEducationMinistryofChina (No .2 0 0 2 0 0 5 5 0 0 2 )andtheNaturalScienceFoundationofTianjin (No .0 3 3 60 3 5 11)
文摘The imprinted polymeric film was synthesized on the glass-carbon electrodes directly. The response to the template molecule-dopamine and other molecules with similar structure was measured by cyclic voltammetry. The response of dopamine on imprinted electrode was much higher than that of other molecules, because of the existing of micro-cavities in polymeric film fitting with the size and shape of dopamine in the imprinted polymer. Experimental results showed that dopamine can be enriched by the imprinted film, therefore increasing the sensitivity of the sensor. The imprinted film could also efface the interference of ascorbic acid, indicating that dopamine can be determined with a large excess of ascorbic acid.
文摘Saffron in aqueous solution was studied via electrochemical analysis with KCl as a supporting electrolyte using cyclic voltammetric technique to determine the redox current peaks at different concentration,pH and scan rate(SR).It was found that an oxidation current peak appeared at potential+268 mV and two reduction current peaks at−282 and−850 mV.The oxidation current peak of saffron disappeared in alkaline medium at pH=12.An enhancement was observed in acidic medium at pH=6.Based on Randel equations and by using different scan rates,the diffusion coefficient(D_(f))for oxidation-reduction current peaks of saffron in KCl solution was determined with nearly equal values as of 1.87×10^(−5) and 1.12×10^(−5) cm^(2)/s,respectively.The results indicate a low detection limit of the different concentrations of saffron in KCl solution as determined from the calibration graph,and a high reliability revealed by the relative standard deviation(RSD).Stability of the GCE for oxidationreduction current peaks was recorded as±7.12%and±1.04%,respectively.
文摘Cardamom oil is one of the active herbs used as a treatment in different diseases by the function of the blood serum components.Among the methods used for identification of function group which acted in the human body,the method of electrochemical analysis using cyclic voltammetry was used to determine the effectiveness of cardamom by the oxidation-reduction reaction in the blood medium.Results showed that the cardamom compound presented peaks of oxidation-reduction in the blood serum medium of 0.8 and-0.65 V,respectively.The oxidation peak disappeared in alkaline pH;hence,the cardamom acted as anti-oxidative compound in alkaline medium and with ascorbic acid.But the oxidation peak was enhanced in acidic pH.Other electrochemical parameters of cardamom in blood serum medium were determined,including studies on different scan rates,reliability and stability.
文摘A new modified ion selective electrode with carbon and metal oxide nanoparticles to increase sensitivity and selectivity to measure the trace concentration of heavy elements in solutions and pharmaceutical compounds.by preparing the Nano-oxides of ZnO,CuO and MnO_(2) using a hydrothermal method.The temperature and pH of the electrode studied to select the best conditions.Where the voltmogram recorded a single signal in relation to the oxidation and reduction process of the zinc element by a reversable mechanism rever to one electron transmission and a quasi-reversable signal for the copper element,and irreversible signal for the manganese element resulting from the transmission of two electrons.The thermodynamic and kinetic factors were also studied and finally the standard mixture of the elements salt was detection to electrode sensitivity mutation the result show the new electrode can distinguish between the signals produced by the oxidation and reduction process of the three elements as the same time with three deferent peaks for oxidation and two peaks of redaction.
文摘A new modified working electrode of glassy carbon electrode with nanoparticles of SiO_(2)(SiO_(2) nanoparticles/GCE)was prepared by mechanical attachment method.The modified electrode(SiO_(2) nanoparticles/GCE)was characterised by electrochemical analysis using cyclic voltammetric technique to evaluate this electrode as nano-sensor.A standard solution of 1 mM K_(4)[Fe(CN)_(6)]with 1 M KCl as an electrolyte was used to study the redox current peaks of FeⅡ/FeⅢ ions on the modified electrode at different concentrations,scan rates,pH,determination of diffusion coefficient(Df),reliability and stability of the modified electrode.It was found the new nano-sensor(SiO_(2) nanoparticles/GCE)had enhancement for the oxidation and reduction current peak of FeII/FeIII ions of about 1.29 and 1.58µA,respectively.The current ration value of the new modified electrode was I_(pa)/I_(pc)=1.7 with the peak separation of ∆Epa-c=140 mV,which demonstrated that the new modified electrode acted in electrolyte as irreversible and heterogeneous reaction,had low detection limit,and enhanced the redox current peaks in acidic pH with good reliability and stability of nanoparticles on the surface of GCE.
