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谢青季, Liang Tan, Qingji Xie, * Shouzhuo Yao*
Electroanalysis 2004, 16, No.19,-0001,():
-1年11月30日
The electrochemical redox processes of pyridoxine hydrochloride (VB6) at a poly (methylene blue) film modified glass carbon electrode (PMBE) in a phosphate buffer solution (PBS, pH 8.0) were studied by cyclic voltammetry. The VB6 electrode reaction with quasi-reversible characteristics was diffusion-controlled at low scan rates and adsorptioncontrolled at high scan rates. The anodic peak current positive to 0.6V (vs. SCE) was found to be proportional to the concentration of VB6 in the range of 0.010 to 1.03mg
Pyridoxine hydrochloride,, Spectroelectrochemistry,, Poly(, methylene blue), ,, Chemically modified electrode
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谢青季, Qingji XIE, † Youyu ZHANG, Xiaoming XIAO, Yanghui GUO, Xiangjun WANG, and Shouzhuo YAO
ANALYTICAL SCIENCES FEBRUARY 2001, VOL. 17,-0001,():
-1年11月30日
An electrochemical quartz crystal impedance system (EQCIS) was used to study the resonance behavior of an AT-cut 9-MHz piezoelectric quartz crystal (PQC) with its Au electrode partially immersed in KCl, Na2SO4 and NaClO4 aqueous solutions, respectively. An in situ determination of the immersed area and the height of the electrode was achieved by simultaneous measurements of the PQC electroacoustic admittance and the electrochemical impedance. The rising of the solution meniscus for a gold electrode partially immersed in aqueous solutions was found at oxygen reduction potentials and evaluated versus the electrolyte, electrolyte concentration, solution pH and oxygen concentration. The solution meniscus rising was explained based on a lowering of the contact-angle hysteresis and a continued collection of the water product at the solid-gas-solution interface during oxygen reduction.
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谢青季
,-0001,():
-1年11月30日
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谢青季, Xinman Tu, † Qingji Xie, *, †, ‡ Canhui Xiang, ‡ Youyu Zhang, † and Shouzhuo Yao†
J. Phys. Chem. B 2005, 109, 4053-4063,-0001,():
-1年11月30日
ance (PQCI) analysis was proposed as a novel multiparameter method for investigating the cyclic voltammetric growth of poly(o-phenylenediamine) (PoPD) thin films at Au electrodes in aqueous solutions of various pH values and the potentiostatic microetching (localized degradation) of these films in 0.10mol/L aqueous H2-SO4 for comparative examinations on polymer porosity and stability. Two potential-sweep ranges, -0.4 to 0.9 (I) and 0 to 0.9 (II) V versus SCE, and four solutions, acidic (A, 0.20mol/L H2SO4 + 0.10mol/L Na2-SO4; B, 0.10 mol/L H2SO4+ 0.20mol/L Na2SO4), neutral (C, 0.10mol/L PBS + 0.20mol/L Na2SO4, pH 7.2), and alkaline (D, 0.20mol/L NaOH+ 0.20mol/L Na2SO4) aqueous solutions, were selected for PoPD growth. The pH increase for the polymerization solution increased the molar percentage of polyaniline-like chains in PoPD, as quantified from the current peaks at 0.6 V versus a saturated calomel electrode (SCE) for the oxidation of -NH2 groups in as-prepared PoPD (grown from solutions C and D) during their redox switching in 0.10mol/L aqueous H2SO4 for the first time. The unusual PQCI responses observed at negative potentials (potential range I) in the first several potential cycles during the cyclic voltammetric growth of PoPD in acidic and neutral solutions have been reasonably explained as being due to the precipitation/dissolution of the poorly soluble phenazinehydrine charge-transfer complexes developed during redox switching of oligomers for the first time, which brought about much less compact PoPD films and their higher degradability than those grown in the same solution but over potential range II. SECM, scanning electron microscopy (SEM), and piezoelectric quartz crystal (PQC) frequency were used to estimate the sizes of etched microscale spots. In addition, the x-, y-, or z-axis movement of a Pt microelectrode of 25-μm diameter near the PQC electrode was found to influence negligibly the PQCI responses in 1.0mol/L aqueous Na2SO4 containing K4Fe(CN)6 up to 0.10mol/L, and a new protocol of dynamically electrodepositing silver microwires via the chemical-lens method was proposed for examining the local mass-sensitivity distribution on the PQC surface.
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谢青季, Zhijun Cao, Qingji Xie *, Meng Li, Shouzhuo Yao
Journal of Electroanalytical Chemistry 568 (2004) 343-351,-0001,():
-1年11月30日
A simultaneous EQCM-fluorescence method has been proposed as a novel and informative tool for the study of the adsorption/desorption and oxidation for vitamin B6 (pyridoxol) at a polycrystalline Au electrode in aqueous KOH. The oxidation of pyridoxol was irreversible and accompanied by a strong electrogenerated fluorescence emission peaking at 443nm when excited at 360nm. Theadsorption and desorption of the oxidation product were found in the double layer region and were discussed by analyzing the simultaneous fluorescence and EQCM data. In addition, the voltammetrically electrogenerated fluorescence is proposed as a new and sensitive method for assay of pyridoxol with satisfactory results.
Simultaneous EQCM-fluorescence study, Pyridoxol oxidation, Au electrode, Alkaline solution, Quantitative analysis
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