Abstract Currently, the search for a more economical alternative with adequate selectivity, sensitivity and reproducibility in the determination of metallic ions is important for the development of reliable methodologies for the determination of these contaminants. This work investigates a boron-doped micro/nano diamond electrode, with different morphology and structure compared to those discussed in the literature, for the detection of copper and iron in aqueous and ethanolic environments. Internal validation of the Square Wave Voltammetry was applied. The methodology was submitted to validation by: selectivity, linearity, precision (interday test), accuracy (percentage of recovery) and detection and quantification limits. The results indicated that this type of electrode showed good response to determinations in aqueous and ethanolic environments, with good selectivity, linearity, accuracy (recovery between 70% and 110%) and precision, presenting the best detection and quantification limits for the aqueous. The methodology using a boron-doped diamond micro/nano electrode was suitable for the determination of copper and iron metals in both matrices.

Morphological and microstructure properties of reticulated vitreous carbon (RVC) were analyzed by scanning electron microscopy (SEM), micro-Raman spectroscopy and x-ray diffraction (XRD) techniques as a function of heat treatment temperature (HTT). Samples produced in the HTT range of 1000 to 2400 K have demonstrated a strong dependence of HTT in their structural order mainly attributed to the presence of hydrogen and oxygen (heteroatoms), originated from precursor. In this range, the material is changed from pyropolymer to carbon. The polyfurfuryl alcohol precursor has furanic groups and its cure originates methylenical bonds and sulphur atoms. At HTT higher than 1300 K, these atoms are gradually liberated from the material generating a discrete structure ordering.

Semiconductor boron-doped CVD diamond films were prepared on Si substrates by the hot filament technique. The surface morphology analysis by SEM presented continuous and well faceted films. The samples were grown with different boron concentrations by controlling the B/C ratio in the feeding gas. Raman results showed a drastic change of diamond films for different doping levels. The characteristic line at 1332 cm-1decreases and shifts to lower energy as a function of the film resistivity. It was also observed a broad peak around 1220 cm-1 caused by the incorporation of boron in the diamond lattice. Photocurrent-voltage behaviour of undoped and boron-doped diamond electrodes was investigated in dark and UV visible irradiation. The voltammograms showed that doped electrodes illuminated with a xenon lamp exhibited currents significatively higher because of the increased conductivity. For undoped electrodes it was observed a small photocurrent for anodic and cathodic polarization in the order ofmuA for the potential range of +1.0 V and -1.0 V (Ag/AgCl), for 1.0 M KCl. Mott-Schottky plots studied the interfacial processes at diamond-electrolyte junction. The flatband potential Uf b was found between 0.6 and 0.8 V (Ag/AgCl) which varies with the presence of sp² -type carbon as an impurity. From the curve slope the acceptor concentrations were found in the range of 10(18) and 10(21) cm-3 .These values agree with the estimated concentration obtained by Raman measurements.