Cuihong Zhang

Silver oxide nanowalls grown on Cu substrate as an enzymeless glucose sensor.

Ag(2)O nanowalls consisting of densely packed nanoplates based on a Cu substrate were synthesized through a facile one-pot hydrothermal method. A new enzymeless glucose sensor of Cu-Ag(2)O nanowalls was fabricated. The Cu-Ag(2)O nanowalls showed higher catalysis on glucose oxidation than traditional Ag(2)O nanoflowers and Cu-Ag(2)O nanospindles. At an applied potential of 0.4 V, the sensor produced an ultrahigh sensitivity to glucose (GO) of 298.2 microA mM(-1). Linear response was obtained over a concentration range from 0.2 mM to 3.2 mM with a detection limit of 0.01 mM (S/N = 3). Satisfyingly, the Cu-Ag(2)O nanowalls modified electrode was not only successfully employed to eliminate the interferences from uric acid (UA) acid ascorbic (AA) and also fructose (FO) during the catalytic oxidation of glucose. The Cu-Ag(2)O nanowalls modified electrode allows highly sensitive, excellently selective, stable, and fast amperometric sensing of glucose and thus is promising for the future development of nonenzymatic glucose sensors.

Electrochemical determination of copper(II) using co-poly (cupferron and β-naphthol)/gold nanoparticles modified glassy carbon electrodes

A novel, simple and reliable method for the determination of trace copper on glassy carbon electrodes (GCEs) modified with co-poly(cupferron and β-naphthol)/gold nanoparticles (GNPs) is reported. The present work realized the application of principle of organic co-precipitation in solution into electrochemical analysis. First, the co-poly(cupferron and β-naphthol) was electrochemically deposited on the prepared GNPs/GCE by CV scanning in order to obtain co-poly(cupferron and β-naphthol)/GNPs/GCE. Then, the chelating ligand cupferron on the surface of the modified electrode and copper ion in the solution form the chelate complex (Cu(II)-Cpf), at the same time, the Cu(II)-Cpf was induced to be adsorbed by the carrier β-naphthol on the surface of the modified electrode by the principle of organic co-precipitation. Thus, the Cu2+ of the coprecipitated complexation can be detected at the co-poly(cupferron and β-naphthol)/GNPs/GCE. Therefore, preconcentration-separation and electrochemical detection of trace copper were simultaneously and synchronously carried through. After optimization, two linear responses were obtained in the concentration range from 9.0 × 10−10 to 4.5 × 10−8 M and 5.0 × 10−8 to 1.5 × 10−6 M, with a low detection limit of 5.0 × 10−11 M. This modified GCE does not present any significant interference from Cd2+, Ag+, Fe3+, Pb2+, Cr3+, Zn2+, NO3−, Cl−, SO42− and EDTA. No deterioration was observed in the electrode response during at least 3 weeks of successive measurements. And the modified electrode shows high selectivity, sensitivity and stability. The proposed method provides a new way for the separation, enrichment and electrochemical detection of trace copper ion.

A study of the separation, enrichment and determination of trace amounts of Hg2+ synchronously

A novel, simple and highly reliable method for the determination of trace amounts of mercury on a glassy carbon electrode (GCE) modified with a compound of crystal violet and multi-walled carbon nanotubes (CV+I−/MWCNTs) is reported. The principle of organic co-precipitation in solution was applied to the application of electrochemical analysis. First, the CV+/MWNTs modified electrode was immersed in solution with I−, CV+ and I− to form an ion association complex (CV+I−) as the carrier by the following reaction. Hg2+ was added into solution, where it reacted with I− to form HgI42−, then in the presence of CV+ an organic coprecipitator formed HgI42−·2CV+ by electrostatic adsorption. Finally, the HgI42−·2CV+ was adsorbed by the carrier CV+I− onto the surface of the modified electrode by the principle of organic co-precipitation. Meanwhile, trace mercury could be detected on the CV+I− and MWCNTs modified electrode (CV+I−/MWCNTs/GCE) by an electrochemical method. Therefore, preconcentration, separation and electrochemical detection of trace mercury were simultaneously and synchronously carried out. After optimization of the method, a linear response was obtained in the concentration range from 5.0 × 10−9 – 1.9 × 10−6 M, with a detection limit of 1.0 × 10−10 M. The modified electrode shows high selectivity, sensitivity and stability. This modified GCE does not present any significant interference from Cd2+, Cu2+, Ag+, Fe3+, Pb2+, Cr3+, Zn2+. No deterioration was observed in the electrode response during at least 3 weeks of successive measurements. The proposed method enables the separation, enrichment and electrochemical detection of trace mercury in aqueous solutions.