Estudos eletroquímicos e teóricos sobre a oxidação de compostos orgânicos modelo no eletrodo de diamante dopado com boro: comportamento eletroquímico, mecanismos de oxidação e DFT

Abstract

The Electrochemical Oxidation is a kind of process that can occur directly at the anode from a direct transfer to the surface, or also by means of indirect oxidation by the generation of active oxygen species which can be physically adsorbed (in form of hydroxyl radical (● OH)), or chemically adsorbed (oxygen is present in oxide structure) on the electrode surface. this process is related to the type of anode material used and its electrocatalytic activity. However, this activity can also be impaired due to the formation of polymeric films, production of parallel oxidant reactions as well reaction of oxygen evolution. Among the most studied electrocatalytic material is diamond films doped with boron (BDD). the BDD electrode has excellent electrochemical properties such as stability at high current densities, corrosion stability, inert surface with low adsorption properties, and hardness. The high efficiency of the BDD for removal of organic compounds is attributed to their ability to produce a large amount of hydroxyl radicals by the electrolysis of water. These radicals have high reactivity with organic compounds, due to their weak interaction (weakly adsorbed) with the film BDD, they are also not selective and completely mineralize organic pollutants with a high current efficiency. However, some organic compounds are easy to degradation than others, as well as certain organic compounds also interact with the surface of BDD. Thus, because of the need to understand the chemical process at the molecular level, including computational theoretical studies that are of most interest, which are developed physico-chemical calculations arising from quantum chemistry, using Density Functional Theory (DFT). The DFT is systems with many electrons using functions representing the electron density of molecules in order to obtain electronic, atomic charges and derivatives of energy the potential energy surface of a chemical reaction, to evaluate the stability of the compounds and understand the reaction mechanisms followed and proposed. The objective of this work was the use of BDD to study the electrochemical behavior of organic compounds (hydroquinone, catechol, resorcinol, acetic acid, formic acid and oxalic acid) as well as the understanding of the degradation process of the same when in electrolysis. Moreover, computational studies on the behavior of chemical species across the BDD electrode with the intention of obtaining the organic compound interaction settings on the surface of the electrode or the understanding to unravel the interactions between strong oxidizing species in solution with organic compounds during its degradation.