Jianhong Pei

Electrochemical study and flow-injection amperometric detection of trace NO2 at CuPtCl6 chemically modified electrode

A thin film of mixed-valent CuPtCl(6) is deposited on a glassy carbon electrode by continuous cyclic scanning in a solution containing 3x10(-3) M CuCl(2)+3x10(-3) M K(2)PtCl(6)+1 M KCl in the potential range from 700 to -800 mV. The cyclic voltammetry is used to study the electrochemical behaviors of nitrite on CuPtCl(6)/GC modified electrode and the electrode displays a good catalytic activity toward the oxidation of nitrite. The effects of the film thickness, pH, the electrode stability and precision have been evaluated. Experiments in flow-injection analysis are performed to characterize the electrode as an amperometric sensor for the detection of nitrite. The modified electrode shows a wide dynamic range, quite a low detection limit and short response time. The linear relationship between the flow-injection peak currents and the concentrations of nitrite is at a range of 1x10(-7)-2x10(-3) M with a detection limit of 5x10(-8) M.

A Novel Voltammetric Probe with Individually Addressable Gel-Integrated Microsensor Arrays for Real-Time High Spatial Resolution Concentration Profile Measurements

In this article, the development of a novel voltammetric system for real-time, high spatial resolution trace element concentration profile measurements at the sediment-water interface, or other interfaces, is reported. The heart of this system is a novel gel-integrated Hg-plated Ir-based 64 individually addressable microsensor arrays. The gel membrane minimizes fouling problems and insures high stability of the Hg semidrops. Measurements were performed simultaneously over the 64 lines using a powerful multiplexing system and a single potentiostat. The voltammetric probe and sensor have been described in detail. This voltammetric system has been characterized by running both cyclic voltammetry (CV) in hexacyanoferrate(III) solution using the gel-integrated Ir-based microsensor and square-wave anodic stripping voltammetry (SWASV) in Pb(II) and Cd(II) solution using the gel-integrated Hg-plated Ir-based microsensor. The results showed that reproducible and reliable simultaneous measurements can be obtained over the 64 individually addressable lines even with fast dynamic techniques such as SWASV. Moreover, theoretical and experimental data were in good agreement. Profiling capability has also been demonstrated.

Preparation, characterization and application of an electrode modified with electropolymerized CuPtCl6

Abstract We report the electropolymerization of K2PtCl6 on various electrode substrates by the cyclic scanning of the potential in the presence of CuCl2 and in the potential range between 700 and −800 mV (vs. SCE). Cu2+ was found to be a necessary ion for the formation and stabilization of the polymeric film. The potential range of the cyclic scanning was found to be crucial for the formation of the film. An energy dispersive X-ray spectrometry study of the modifier film indicates that it contains copper, platinum, and chloride ions, respectively. The scanning electron microscopy image reveals the formation of the nanometer-sized modifier particles dispersed on the substrate electrode. The electrochemical behavior of the modified electrode was studied in detail in electrolyte solutions containing various cations including Cu2+, H+, Fe3+, Cr3+. On the basis of these studies, a mechanism of the electropolymerization on the substrate surface was proposed which suggests for the modifier film a one-dimensional, polymeric, mixed-valent, and negative-charge-carrying platinum complex stabilized by the Cu2+/Cu+ as the counter ions. The composition of the modifier film is therefore proposed to be [CuPtCl6 · CuPtCl4]n, and denoted as CuPtCl6|GC to signify the necessary starting components. H+/H, Fe3+/Fe2+ and Cr3+/Cr2+ display remarkably reversible redox behavior at the CuPtCl6|GC electrode. The modified electrode also displays very good electrocatalytic activity in the oxidation of ascorbic acid, H2O2, S2O32−, and NO.

Preparation, characterization and application of an electrode modified with electropolymerized CuPtBr6 film

Abstract We report the electropolymerization of CuPtBr 6 film on the electrode substrate by cyclic scanning in 3×10 −3 M CuCl 2 +3×10 −3 M K 2 PtBr 6 +1 M KCl in the potential range from +700 to −800 mV (versus the saturated calomel electrode (SCE)). Several surface analysis techniques were used to characterize the film on the electrode surface. A sharp and intense diffraction peak in the X-ray diffraction (XRD) pattern indicates that the film has a high preferential orientation. The electrochemical behavior of the modified electrode was studied in detail in electrolyte solutions containing various cations. On the basis of these studies, a mechanism of electropolymerization was proposed which suggests for the modifier film a one-dimensional, polymeric structure formed from a negatively charged platinum compound, stabilized by Cu 2+ and Cu + as the counter ions. The composition of the modified film is proposed to be [CuPtBr 6 ·CuPtBr 4 ] n , and is denoted as CuPtBr 6 /glassy carbon (GC) to highlight the starting components. H + /H, Fe 3+ /Fe 2+ and Cr 3+ /Cr 2+ display remarkably reversible redox behaviors at the CuPtBr 6 /GC electrode. The modified electrode also displays good catalytic activity toward the oxidation of ascorbic acid, hydrogen peroxide, S 2 O 3 2− , and especially nitric oxide.

Amperometric glucose enzyme sensor prepared by immobilizing glucose oxidase on CuPtCl6 chemically modified electrode

A simple, sensitive, stable and low-cost glucose sensor with a fast response that operates under aerobic solution conditions is described. The electrode consisted of a CuPtCl6 modified film deposited on the surface of the glassy carbon electrode onto which the glucose oxidase was immobilized via cross-linking of glutaraldehyde in the presence of bovine serum albumin (BSA). The electropolymerized CuPtCl6 film was prepared by continuously cyclically scanning between 700 mV and –800 mV (vs. SCE) in a solution containing CuCl2 and K2PtCl6. The preparation and the performance of the enzyme electrode have been discussed. The effects of enzyme loading, pH, and the temperature have been studied. The experiments on interference and specificity have also been demonstrated. The enzyme electrode exhibits an excellent biocatalytic activity and stability. The enzyme electrode provides a linear response to glucose over a concentration range of 2×10–6 M to 1×10–3 M with a detection limit of 1×10–6 M.

Layer-by-layer Assembled Molecular films—III: Electrochemical Assembly and Electropolymerization of Noble Metal Complexes

Abstract A class of inorganic films based on electrochemically assembled Pt(IV/II) and Pd(IV/II) complexes were prepared. The films display very interesting electrocatalytic and electrochromic properties.