Conferência 5: Recent advances in carbon electrode materials and their application in electrochemistry

Boron-doped nanocrystalline diamond and nitrogen-incorporated tetrahedral amorphous carbon (ta-C:N) thin-films have emerged as next-generation electrodes that are useful for a variety of electroanalytical applications. The interesting electrochemical properties of boron-doped diamond are well established. ta-C:N materials are a diamond-like carbon that consist of a mixture of sp 2 and sp 3 -bonded carbon. They exhibit many of the excellent properties (wide potential window, low background current, good responsiveness without conventional pretreatment and microstructural stability) of boron-doped diamond but can be deposited (200-400 nm thickness) by physical vapor deposition near room temperature. In electroanalysis, specifically electrochemical detection coupled with flow injection analysis (FIA), ta-C:N electrodes offer significant improvements in the analytical detection figures of merit (linear dynamic range,limit of detection, response reproducibility and response stability) for analytes as compared to conventional sp 2 carbon electrodes (e.g., glassy carbon). They appear to be particularly useful for detecting analytes that require high positive potentials for oxidation due to the material’s microstructural stability. The electrodes also appear to be resistant to fouling. So far, there has been little research reported on the basic electrochemical properties of these electrodes in aqueous electrolytes and none in organic electrolyte/solvent systems. A focus of our current research is understanding how capacitance, molecular adsorption, and electron-transfer kinetics in aqueous and organic electrolytes solutions, as well as room temperature ionic liquids (RTILs), correlate with the material properties of ta-C:N films. In the presentation, we report on some material characterization of boron-doped diamond and ta-C:N thin-film electrodes, some electroanalytical performance data for the two electrodes for the analysis of tyrosine and tryptophan which require positive potentials for detection, and some preliminary data for the electrochemical behavior of the two electrodes in organic electrolyte solutions and RTILs.