A cobalt-iron alloy thin-film electrode-based electrochemical hydrogen-phosphate-ion sensor was prepared by electrodepositing on an Au-coated Al2O3 substrate from an aqueous solution of metal-salts. The use of a cobal...A cobalt-iron alloy thin-film electrode-based electrochemical hydrogen-phosphate-ion sensor was prepared by electrodepositing on an Au-coated Al2O3 substrate from an aqueous solution of metal-salts. The use of a cobalt-iron alloy electrode greatly improved the hydrogen-ion sensor response performance, i.e., the sensor worked stably for more than 7 weeks and showed a quick response time of several seconds. Among the cobalt and iron alloy systems tested, the electrodeposited Co58Fe42 thin-film electrode showed the best EMF response characteristics, i.e., the sensor exhibited a linear potentiometric response to hydrogen-phosphate ion at the concentration range between 1.0 × 10–5 and 1.0 × 10–2 M with the slope of –43 mV/decade at pH 5.0 and at 30℃. A sensing mechanism of the Co-based potentiometric hydrogen-phosphate ion sensor was proposed on the basis of results of instrumental analysis.展开更多
The phosphate protective film and micro-galvanic corrosion of biological Mg-3Zn-xNd (x = 0, 0.6, 1.2) alloys were investigated by scanning and transmission electron microscopy, quasi-in-situ observation, scanning Kelv...The phosphate protective film and micro-galvanic corrosion of biological Mg-3Zn-xNd (x = 0, 0.6, 1.2) alloys were investigated by scanning and transmission electron microscopy, quasi-in-situ observation, scanning Kelvin probe force microscopy (SKPFM) and electrochemical tests. The results revealed the Mg-Zn-Nd phases formed in Mg-3Zn alloy contained with Nd. Adding Nd resulted in a significant decline in the cracks of the phosphate protective film and micro-galvanic corrosion of alloys, which were recorded by quasi-in-situ observation. In addition, the Volta potential difference of Mg-Zn-Nd/α-Mg (~ 188 mV) was lower than MgZn/α-Mg (~ 419 mV) and Zn-rich/α-Mg (~ 260 mV), and the corrosion rates of alloys markedly decreased after the addition of 0.6 wt% Nd. The improvement in corrosion resistance of Nd-containing alloys was mainly attributed to the following: (i) the addition of Nd reduced the Volta potential difference (second phases/α-Mg);(ii) the phosphate protective film containing Nd_(2)O_(3) deposited on the surface of the alloys, effectively preventing the penetration of harmful anions.展开更多
As a material with good corrosion resistance,5083 aluminum alloy has a great application prospect in marine environment.In this work,the corrosion characteristics of 5083 aluminum alloy in seawater containing phosphat...As a material with good corrosion resistance,5083 aluminum alloy has a great application prospect in marine environment.In this work,the corrosion characteristics of 5083 aluminum alloy in seawater containing phosphate were investigated with Potentiodynamic Polarization,Electrochemical Impedance Spectroscopy (EIS),Scanning Electron Microscope (SEM),Energy Dispersive Spectroscopy Analysis (EDSA),X-ray Photoelectron Spectroscopy (XPS) and Laser Confocal Microscope.The results indicated that the effects of phosphate in seawater were two-fold.Firstly,phosphate slightly accelerated the corrosion of 5083 in seawater in the early stage of corrosion.HPO_4~(2-)competed with OH~-in the adsorption process on the alloy surface,which weakened the contact between OH~-and Al~(3+)near the interface of the alloy,and inhibited the formation as well as the self-repair of the passive film,thus accelerating the activation dissolution process.Compared with the natural seawater,the charge transfer resistance of 5083 in the seawater containing phosphate decreased faster during the early stage of corrosion,and the corrosion current density i_(corr) was higher in seawater containing phosphate.On the other hand,the addition of phosphate would not affect the cluster distribution of the second phase of 5083 in seawater,but it changed the composition of the corrosion product layer and had an obvious inhibitory effect on the local corrosion of 5083 in seawater.After 16-day exposure,shallower and more sparsely distributed pits could be observed on the derusted surface of 5083 in the seawater containing phosphate,and the pitting coefficient in the seawater containing phosphate was significantly lower than that in natural seawater.The reduction of pitting tendency could be realized mainly through two ways.First,the HPO_4~(2-)adsorbed on the surface of the passive film in the early stage of corrosion and repeled the corrosive anions such as Cl~-.Second,phosphate participated in the construction of the Ca HPO_4 precipitation film,which acted as a barrier and protection.展开更多
Polyionic complex DHP-PDDA was prepared by reacting anionic surfactant dihexadecyl phosphate (DHP) with polycationic poly(diallyldimethyl ammonium) (PDDA). Thin films made from DHP-PDDA with incorporated hemoglobin (H...Polyionic complex DHP-PDDA was prepared by reacting anionic surfactant dihexadecyl phosphate (DHP) with polycationic poly(diallyldimethyl ammonium) (PDDA). Thin films made from DHP-PDDA with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemistry and other techniques.展开更多
This study investigated the behavior and molecular organization of synthetic artificial mimic molecules that resemble the following tetraether lipids: di-O-hexadecyl-glycero-3-phosphatidyl-glycerol (DHGPG) and bis-4-d...This study investigated the behavior and molecular organization of synthetic artificial mimic molecules that resemble the following tetraether lipids: di-O-hexadecyl-glycero-3-phosphatidyl-glycerol (DHGPG) and bis-4-dodecylphenyl-12-phosphate. These molecules were analyzed using Langmuir film balance, ellipsometry and atomic force microscopy. The monolayer Langmuir-Blodgett films of DHGPG and bis-4-dodecylphenyl-12-phosphate were stable on the solid surface silicon wafers. The ellipsometry and AFM results showed that monolayers Langmuir-Blodgett films of DHGPG and bis-4-dodecylphenyl-12-phosphate were present, and the thickness of the observed films varied from 1.2 - 5.0 nm.展开更多
文摘A cobalt-iron alloy thin-film electrode-based electrochemical hydrogen-phosphate-ion sensor was prepared by electrodepositing on an Au-coated Al2O3 substrate from an aqueous solution of metal-salts. The use of a cobalt-iron alloy electrode greatly improved the hydrogen-ion sensor response performance, i.e., the sensor worked stably for more than 7 weeks and showed a quick response time of several seconds. Among the cobalt and iron alloy systems tested, the electrodeposited Co58Fe42 thin-film electrode showed the best EMF response characteristics, i.e., the sensor exhibited a linear potentiometric response to hydrogen-phosphate ion at the concentration range between 1.0 × 10–5 and 1.0 × 10–2 M with the slope of –43 mV/decade at pH 5.0 and at 30℃. A sensing mechanism of the Co-based potentiometric hydrogen-phosphate ion sensor was proposed on the basis of results of instrumental analysis.
基金support by the National Natural Science Foundation of China(No.51961026).
文摘The phosphate protective film and micro-galvanic corrosion of biological Mg-3Zn-xNd (x = 0, 0.6, 1.2) alloys were investigated by scanning and transmission electron microscopy, quasi-in-situ observation, scanning Kelvin probe force microscopy (SKPFM) and electrochemical tests. The results revealed the Mg-Zn-Nd phases formed in Mg-3Zn alloy contained with Nd. Adding Nd resulted in a significant decline in the cracks of the phosphate protective film and micro-galvanic corrosion of alloys, which were recorded by quasi-in-situ observation. In addition, the Volta potential difference of Mg-Zn-Nd/α-Mg (~ 188 mV) was lower than MgZn/α-Mg (~ 419 mV) and Zn-rich/α-Mg (~ 260 mV), and the corrosion rates of alloys markedly decreased after the addition of 0.6 wt% Nd. The improvement in corrosion resistance of Nd-containing alloys was mainly attributed to the following: (i) the addition of Nd reduced the Volta potential difference (second phases/α-Mg);(ii) the phosphate protective film containing Nd_(2)O_(3) deposited on the surface of the alloys, effectively preventing the penetration of harmful anions.
基金supported by the National Natural Science Foundation of China (No. U1706221)。
文摘As a material with good corrosion resistance,5083 aluminum alloy has a great application prospect in marine environment.In this work,the corrosion characteristics of 5083 aluminum alloy in seawater containing phosphate were investigated with Potentiodynamic Polarization,Electrochemical Impedance Spectroscopy (EIS),Scanning Electron Microscope (SEM),Energy Dispersive Spectroscopy Analysis (EDSA),X-ray Photoelectron Spectroscopy (XPS) and Laser Confocal Microscope.The results indicated that the effects of phosphate in seawater were two-fold.Firstly,phosphate slightly accelerated the corrosion of 5083 in seawater in the early stage of corrosion.HPO_4~(2-)competed with OH~-in the adsorption process on the alloy surface,which weakened the contact between OH~-and Al~(3+)near the interface of the alloy,and inhibited the formation as well as the self-repair of the passive film,thus accelerating the activation dissolution process.Compared with the natural seawater,the charge transfer resistance of 5083 in the seawater containing phosphate decreased faster during the early stage of corrosion,and the corrosion current density i_(corr) was higher in seawater containing phosphate.On the other hand,the addition of phosphate would not affect the cluster distribution of the second phase of 5083 in seawater,but it changed the composition of the corrosion product layer and had an obvious inhibitory effect on the local corrosion of 5083 in seawater.After 16-day exposure,shallower and more sparsely distributed pits could be observed on the derusted surface of 5083 in the seawater containing phosphate,and the pitting coefficient in the seawater containing phosphate was significantly lower than that in natural seawater.The reduction of pitting tendency could be realized mainly through two ways.First,the HPO_4~(2-)adsorbed on the surface of the passive film in the early stage of corrosion and repeled the corrosive anions such as Cl~-.Second,phosphate participated in the construction of the Ca HPO_4 precipitation film,which acted as a barrier and protection.
基金the financial support from the National Natural Science Foundation of China (29975003).
文摘Polyionic complex DHP-PDDA was prepared by reacting anionic surfactant dihexadecyl phosphate (DHP) with polycationic poly(diallyldimethyl ammonium) (PDDA). Thin films made from DHP-PDDA with incorporated hemoglobin (Hb) on pyrolytic graphite (PG) electrodes were characterized by electrochemistry and other techniques.
文摘This study investigated the behavior and molecular organization of synthetic artificial mimic molecules that resemble the following tetraether lipids: di-O-hexadecyl-glycero-3-phosphatidyl-glycerol (DHGPG) and bis-4-dodecylphenyl-12-phosphate. These molecules were analyzed using Langmuir film balance, ellipsometry and atomic force microscopy. The monolayer Langmuir-Blodgett films of DHGPG and bis-4-dodecylphenyl-12-phosphate were stable on the solid surface silicon wafers. The ellipsometry and AFM results showed that monolayers Langmuir-Blodgett films of DHGPG and bis-4-dodecylphenyl-12-phosphate were present, and the thickness of the observed films varied from 1.2 - 5.0 nm.
