In situ detection of dopamine using nitrogen incorporated diamond nanowire electrode

[[abstract]]Significant difference was observed for the simultaneous detection of dopamine (DA), ascorbic acid (AA), and uric acid (UA) mixture using nitrogen incorporated diamond nanowire (DNW) film electrodes grown by microwave plasma enhanced chemical vapor deposition. For the simultaneous sensing of ternary mixtures of DA, AA, and UA, well-separated voltammetric peaks are obtained using DNW film electrodes in differential pulse voltammetry (DPV) measurements. Remarkable signals in cyclic voltammetry responses to DA, AA and UA (three well defined voltammetric peaks at potentials around 235, 30, 367 mV for DA, AA and UA respectively) and prominent enhancement of the voltammetric sensitivity are observed at the DNW electrodes. In comparison to the DPV results of graphite, glassy carbon and boron doped diamond electrodes, the high electrochemical potential difference is achieved via the use of the DNW film electrodes which is essential for distinguishing the aforementioned analytes. The enhancement in EC properties is accounted for by increase in sp2 content, new C–N bonds at the diamond grains, and increase in the electrical conductivity at the grain boundary, as revealed by X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure measurements. Consequently, the DNW film electrodes provide a clear and efficient way for the selective detection of DA in the presence of AA and UA.[[booktype]]紙

Role of PtO on the oxidation of Arsenic (III) at Pt RDE in 1M H2SO4 and 1M Na2SO4 through linear sweep voltammetry technique

Linear Sweep Voltammetry (LSV) has been conducted using platinum (Pt) disc electrode to investigate the effect of PtO on the Arsenic (III) oxidation. The changes of As(III) oxidation peak currents and peak potential in 1M H 2 SO 4 and 1M Na 2 SO 4 solutions have been evaluated. Effects of As(III) concentration, scan rate, rotation speed of the electrode on the oxidation of As(III) have been studied extensively. Oxidation peak current values increases linearly with the concentration, scan rate and electrode rotation speed in both of the media and the dependence plot goes through the origin, except in the case of square root of angular velocity and ip a in the Na 2 SO 4 solution. A sharp increase in the As(III) peak current values are found in 1M H 2 SO 4 but not in 1M Na 2 SO 4 medium because of the formation of PtO is higher than in sulphuric acid medium with in the potential range of interest. The PtO layer blocks the available surface area for the As (III) oxidation. Presence of the PtO layer, shifts the As(III) oxidation potential to less positive, suggesting the PtO layer some how facilitates the oxidation of As(III) reaction

Graphene Nanosheet-Wrapped Mesoporous La0.8Ce0.2Fe0.5Mn0.5O3 Perovskite Oxide Composite for Improved Oxygen Reaction Electro-Kinetics and Li-O2 Battery Application

A novel design and synthesis methodology is the most important consideration in the development of a superior electrocatalyst for improving the kinetics of oxygen electrode reactions, such as the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in Li-O2 battery application. Herein, we demonstrate a glycine-assisted hydrothermal and probe sonication method for the synthesis of a mesoporous spherical La0.8Ce0.2Fe0.5Mn0.5O3 perovskite particle and embedded graphene nanosheet (LCFM(8255)-gly/GNS) composite and evaluate its bifunctional ORR/OER kinetics in Li-O2 battery application. The physicochemical characterization confirms that the as-formed LCFM(8255)-gly perovskite catalyst has a highly crystalline structure and mesoporous morphology with a large specific surface area. The LCFM(8255)-gly/GNS composite hybrid structure exhibits an improved onset potential and high current density toward ORR/OER in both aqueous and non-aqueous electrolytes. The LCFM(8255)-gly/GNS composite cathode (ca. 8475 mAh g−1) delivers a higher discharge capacity than the La0.5Ce0.5Fe0.5Mn0.5O3-gly/GNS cathode (ca. 5796 mAh g−1) in a Li-O2 battery at a current density of 100 mA g−1. Our results revealed that the composite’s high electrochemical activity comes from the synergism of highly abundant oxygen vacancies and redox-active sites due to the Ce and Fe dopant in LaMnO3 and the excellent charge transfer characteristics of the graphene materials. The as-developed cathode catalyst performed appreciable cycle stability up to 55 cycles at a limited capacity of 1000 mAh g−1 based on conventional glass fiber separators

Nanoparticulate peroxidase/catalase mimetic and its application

10.1002/chem.201200643Chemistry - A European Journal18298906-8911CEUJ