Influência da estrutura e morfologia de eletrodos de diamante dopados com boro nos processos redox de complexos derivados da Tiossemicarbazona

Abstract

This work presents a detailed study of boron-doped diamond electrodes with varying doping levels, considering their obtaining, morphology, structure and electrochemical application in the redox study of Thiosemicarbazones (TSCs). To this end, this work was carried out in three stages where, firstly, organic compounds were obtained by varying the structures at the terminal nitrogen of five ligands (HOBzD4H, HOBzD4methyl, HOBzD4dimethyl and HOBzD4ethyl) and then these were complexed with the metal Ni. After obtaining these compounds, they were characterized to prove that their structures were obtained. The compounds were characterized by Ultraviolet-Visible, Infrared and Nuclear Magnetic Resonance. The second stage consisted of obtaining microcrystalline diamond films doped with boron at five different doping levels (1000, 2000, 3000, 5000 and 8000 ppm B/C). These films were characterized morphologically, structurally and electrochemically with the aim of investigating the influence of their surface characteristics on electrochemical measurements. The films were characterized by Scanning Electron Microscopy, Raman Scattering Spectroscopy and X-ray Diffraction. The films were produced with well-defined microcrystalline morphology, exhibiting the grain size transition with increasing doping level, highlighting a diamond of good quality, with predominant crystallographic orientation in the (111) direction, presenting differences in the potential window for each electrode, differences in the background current and in the study of reversibility. These results formed the basis for the third stage of this Thesis, where electrodes with different dopings were applied in the redox study of the ligands HOBzD4H, HOBzD4methyl, HOBzD4dimethyl and HOBzD4ethyl and their respective complexes, using Cyclic Voltammetry. The third stage highlighted the 3000 ppm electrode as the best, due to its working range being within the working range of the organic compounds covered in this work, in addition to its low background current. The study of reversibility and its morphological and structural characteristics that favored the electrochemical study can also be highlighted as a result of choosing the 3000 ppm electrode.