Estudo teórico-computacional dos mecanismos eletrocatalíticos da oxidação da água por complexos de cobre(II) com ligantes macrocíclicos.

Abstract

In a contemporary world marked by environmental imbalance, the Energy Transition arises as a solution to mitigate the emission of pollutants from fossil fuels burning. Following this scenario, a promising alternative is, for example, the H2, whose production via water electrolysis faces challenges related to its anodic half reaction, thus evoking the use of catalysts -- e.g. copper(II) complexes bearing macrocyclic ligands -- that remain in constant improvement. For this, it's necessary to elucidate this mechanism, which means to identify the key intermediates and steps for reaction kinetics. Therefore, by means of computational tools, the present work focused on the theoretical study of the water oxidation's electrocatalysis by the coordination complex [Cu(14-TMC)]+2, based on experimental evidence to which the results yielded good correspondence. In this case, the O-O bond formation proceeds through a water nucleophilic attack coupled with a single electron transfer to the metal center or, alternatively, through a crossing point between quartet and doublet potential energy surfaces. Going further, the results of macrocyclic shrinkage were also investigated through [Cu(12-TMC)]2+'s catalysis. Despite of the similar values in terms of energy barrier, this ligand enables the coordination of two water molecules, which impacts the course of reaction. The results, based on electronic and structural fundaments, shed a light on the rational design of ligands aiming better catalytic performance for H2 production.