Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry （CV） curves and electrochemical impedance spe...Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry （CV） curves and electrochemical impedance spectroscopy （EIS）. The results reveal that the anodic behaviors and reaction kinetics of the two anodes vary a lot during the anodic polarization which indicate the formation and stabilization of anodic layer. Compared with conventional Pb-0.8%Ag anode, A1/Pb-0.8%Ag anode has longer time of anodic polarization. At the very beginning of anodic polarization, the two anodes all exhibit higher potential of oxygen evolution reaction （OER） since the reaction is controlled by the transformation step of intermediates. Then, its OER potential is largely diminished and OER rate is deduced from the formation and adsorption of the first intermediate （S-OHms）. In the prolonged anodie polarization, the anodie potential of A1/Pb-0.8%Ag gradually decreases and the final value is more stable than that of conventional Pb-0.8%Ag anode. On the anodic layer after 24 h of anodic polarization, the OER potential is controlled by the formation and adsorption of intermediate. The microstructures of A1/Pb-0.8%Ag and Pb-0.8%Ag anodes after 24 h of anodie polarization were analyzed by scanning electron microscope （SEM）.展开更多
The initial corrosion behavior of pure zinc in a simulated tropical marine atmosphere was investigated using gravimetric method,scanning electron microscope combined with energy dispersive spectroscopy(SEM-EDS),X-ray ...The initial corrosion behavior of pure zinc in a simulated tropical marine atmosphere was investigated using gravimetric method,scanning electron microscope combined with energy dispersive spectroscopy(SEM-EDS),X-ray diffractometry(XRD),Fourier transform infrared spectrometry(FTIR)and electrochemical impedance spectroscopy(EIS).The kinetics of corrosion process is a decelerating process following the empirical equation D=At^n(n<1).The protectiveness of the corrosion product layer could be attributed to the formation of simonkolleite,Zn5(OH)8Cl2·H2O,which could inhibit the rate determining step,namely charge transfer step,of the electrochemical corrosion process.A model of the evolution process of the product layers formed on zinc was proposed.In addition,the regularity of the corrosion rate of zinc as a function of the NaCl deposition rate can be described by a power function.展开更多
LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron micr...LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron microscopy (TEM),energy dispersive spectroscopy (EDS),charge-discharge cycling,cyclic voltammetry (CV),and electrochemical impedance spectroscopy (EIS).Uniform coated layer with a thickness of about 3 nm was observed on the surface of LiNi1/3Co1/3Mn1/3O2 particle by TEM.At 0.5C and 2C rates,1.5% (mass fraction) AlF3-coated LiNi1/3Co1/3Mn1/3O2/Li in 2.8-4.3 V versus Li/Li+ after 80 cycles showed less than 3% of capacity fading,while those of the bare one were 16.5% and 45.9%,respectively.At 5C rate,the capacity retention of the coated sample after 50 cycles maintained 91.4% of the initial discharge capacity,while that of the bare one decreased to 52.6%.EIS result showed that a little change of charge transfer resistance of the coated sample resulting from uniform thin AlF3 layer was proposed as the main reason why its rate capability was improved obviously.CV result further indicated a greater reversibility for the electrode processes and better electrochemical performance of AlF3-coated layer.展开更多
Calcium phosphate film was prepared by electrochemical deposition technology. Subsequently, the alkaline treatment process of calcium phosphate film in 0.1 mol/L NaOH solution was monitored on real time by the piezoel...Calcium phosphate film was prepared by electrochemical deposition technology. Subsequently, the alkaline treatment process of calcium phosphate film in 0.1 mol/L NaOH solution was monitored on real time by the piezoelectric quartz crystal impedance （PQCI） technique. The variations of morphology and composition for the alkaline treatment products were characterized by scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） and X-ray diffraction （XRD）, respectively. The dynamic variations of calcium phosphate can be characterized by the change of equivalent circuit parameters. The results show that the forming process of hydroxyapatite （HA） is composed of three stages： （1） acidic calcium phosphate dissolution; （2） phase transformation; and （3） HA formation. Furthermore, the correlative kinetic equations and parameters are obtained by fitting the static capacitance （C8）-time curves.展开更多
Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium ch...Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.展开更多
We develop a new spectroscopic method to quickly and intuitively characterize the coupling of two microwave-photon-coupled semiconductor qubits via a high-impedance resonator.Highly distinctive and unique geometric pa...We develop a new spectroscopic method to quickly and intuitively characterize the coupling of two microwave-photon-coupled semiconductor qubits via a high-impedance resonator.Highly distinctive and unique geometric patterns are revealed as we tune the qubit tunnel couplings relative to the frequency of the mediating photons.These patterns are in excellent agreement with a simulation using the Tavis-Cummings model,and allow us to readily identify different parameter regimes for both qubits in the detuning space.This method could potentially be an important component in the overall spectroscopic toolbox for quickly characterizing certain collective properties of multiple cavity quantum electrodynamics(QED)coupled qubits.展开更多
基金Project(51004056)supported by the National Natural Science Foundation of China
文摘Anodic behaviors and oxygen evolution kinetics of Pb-0.8%Ag and Al/Pb-0.8%Ag anodes during the initial 24 h zinc electrowinning were investigated with cyclic voltammetry （CV） curves and electrochemical impedance spectroscopy （EIS）. The results reveal that the anodic behaviors and reaction kinetics of the two anodes vary a lot during the anodic polarization which indicate the formation and stabilization of anodic layer. Compared with conventional Pb-0.8%Ag anode, A1/Pb-0.8%Ag anode has longer time of anodic polarization. At the very beginning of anodic polarization, the two anodes all exhibit higher potential of oxygen evolution reaction （OER） since the reaction is controlled by the transformation step of intermediates. Then, its OER potential is largely diminished and OER rate is deduced from the formation and adsorption of the first intermediate （S-OHms）. In the prolonged anodie polarization, the anodie potential of A1/Pb-0.8%Ag gradually decreases and the final value is more stable than that of conventional Pb-0.8%Ag anode. On the anodic layer after 24 h of anodic polarization, the OER potential is controlled by the formation and adsorption of intermediate. The microstructures of A1/Pb-0.8%Ag and Pb-0.8%Ag anodes after 24 h of anodie polarization were analyzed by scanning electron microscope （SEM）.
基金Project (201604046014) supported by Guangzhou Industry-University-Research Collaborative Innovation Alliance Special Program,ChinaProjects (51671197,51601199) supported by the National Natural Science Foundation of China
文摘The initial corrosion behavior of pure zinc in a simulated tropical marine atmosphere was investigated using gravimetric method,scanning electron microscope combined with energy dispersive spectroscopy(SEM-EDS),X-ray diffractometry(XRD),Fourier transform infrared spectrometry(FTIR)and electrochemical impedance spectroscopy(EIS).The kinetics of corrosion process is a decelerating process following the empirical equation D=At^n(n<1).The protectiveness of the corrosion product layer could be attributed to the formation of simonkolleite,Zn5(OH)8Cl2·H2O,which could inhibit the rate determining step,namely charge transfer step,of the electrochemical corrosion process.A model of the evolution process of the product layers formed on zinc was proposed.In addition,the regularity of the corrosion rate of zinc as a function of the NaCl deposition rate can be described by a power function.
基金Project(50542004) supported by the National Natural Science Foundation of ChinaProject(1960-71131100017) supported by Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability.The samples were characterized by X-ray diffractometry (XRD),transmission electron microscopy (TEM),energy dispersive spectroscopy (EDS),charge-discharge cycling,cyclic voltammetry (CV),and electrochemical impedance spectroscopy (EIS).Uniform coated layer with a thickness of about 3 nm was observed on the surface of LiNi1/3Co1/3Mn1/3O2 particle by TEM.At 0.5C and 2C rates,1.5% (mass fraction) AlF3-coated LiNi1/3Co1/3Mn1/3O2/Li in 2.8-4.3 V versus Li/Li+ after 80 cycles showed less than 3% of capacity fading,while those of the bare one were 16.5% and 45.9%,respectively.At 5C rate,the capacity retention of the coated sample after 50 cycles maintained 91.4% of the initial discharge capacity,while that of the bare one decreased to 52.6%.EIS result showed that a little change of charge transfer resistance of the coated sample resulting from uniform thin AlF3 layer was proposed as the main reason why its rate capability was improved obviously.CV result further indicated a greater reversibility for the electrode processes and better electrochemical performance of AlF3-coated layer.
基金Project(2005CB623901) supported by the Major State Basic Research and Development Program of China
文摘Calcium phosphate film was prepared by electrochemical deposition technology. Subsequently, the alkaline treatment process of calcium phosphate film in 0.1 mol/L NaOH solution was monitored on real time by the piezoelectric quartz crystal impedance （PQCI） technique. The variations of morphology and composition for the alkaline treatment products were characterized by scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） and X-ray diffraction （XRD）, respectively. The dynamic variations of calcium phosphate can be characterized by the change of equivalent circuit parameters. The results show that the forming process of hydroxyapatite （HA） is composed of three stages： （1） acidic calcium phosphate dissolution; （2） phase transformation; and （3） HA formation. Furthermore, the correlative kinetic equations and parameters are obtained by fitting the static capacitance （C8）-time curves.
基金supported by the National Natural Science Foundation of China ( Grant No 40876041)Science and Technology Basic Research Program of Qingdao (Grant No 09-1-3-16-jch)the National Key Technology Research and Development Program of China (Grant No 2007 BAB27B01)
文摘Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.
基金supported by the National Key Research and Development Program of China(2016YFA0301700)the National Natural Science Foundation of China(61922074,11674300,61674132,11625419 and 11804327)+2 种基金the Strategic Priority Research Program of the CAS(XDB24030601)the Anhui Initiative in Quantum Information Technologies(AHY080000)financial support by U.S.ARO through Grant No.W911NF1410346 and No.W911NF1710257。
文摘We develop a new spectroscopic method to quickly and intuitively characterize the coupling of two microwave-photon-coupled semiconductor qubits via a high-impedance resonator.Highly distinctive and unique geometric patterns are revealed as we tune the qubit tunnel couplings relative to the frequency of the mediating photons.These patterns are in excellent agreement with a simulation using the Tavis-Cummings model,and allow us to readily identify different parameter regimes for both qubits in the detuning space.This method could potentially be an important component in the overall spectroscopic toolbox for quickly characterizing certain collective properties of multiple cavity quantum electrodynamics(QED)coupled qubits.
