Desenvolvimento de eletrocatalisadores metálicos de baixo custo (Ni, Cu e Zn) para redução de CO2
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Data
2025-01-30
Autores
Barcelos, Marcela Miranda
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Universidade Federal do Espírito Santo
Resumo
Due to a series of environmental problems resulting from the burning of fossil fuels, it has led to an increase in CO2 emissions into the atmosphere, and it is clear that alternatives need to be considered. For example, electrochemical reduction of CO2 (RECO2) appears as a promising alternative to mitigate the impacts of high CO₂ emissions into the atmosphere. Therefore, the objective of this work is to investigate the metallic electrocatalysts of Cu, Ni and Zn for electrochemical reduction of CO2. In order to characterize morphological modifications of the metallic electrodes, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) techniques were used. The results of the XRD analyses revealed that the surface treatments did not alter the structure of the materials. The electrochemical polishing process of copper led to a mostly homogeneous morphology. On the other hand, the ultrasonic process in organic solvent allowed the increase of the roughness of the nickel and zinc electrodes, obtaining a heterogeneous morphology due to the surface reorganization of the materials. The electrochemical studies were performed using Linear Scanning Voltammetry (LSV), the potentiodynamic polarization technique and Electrochemical Impedance Spectroscopy (EIS). The EIS was performed at two different potentials: −0.4 V and −0.6 V vs. Ag/AgCl. The EIS results allowed the identification of substantial changes that occurred before and after the treatment of the electrodes. For the Cu and Ni electrodes, the EIS data indicate greater kinetics, i.e., lower charge transfer resistance. For the Zn electrode, the results indicate that there was competition in the hydrogen evolution reaction (HER). The LVS showed that the Cu and Ni electrodes showed a high current density for the electrochemical reduction reaction of CO2. It was observed that the uniform metallic copper surface acts as an inhibitor of the HER, resulting in a decrease in the overpotential and an increase in the current density for the CO2 reduction reactions. The nuclear magnetic resonance results obtained after the chronoamperometry experiments (constant potential of −2.0 V vs. Ag/AgCl in K2CO3 0.5 mol L–1 for 2 h) indicated the formation of some products from RECO2 such as: ethane, acetone and acetate. These results demonstrate the great potential of these electrocatalysts for the electrochemical reduction of CO2.
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Palavras-chave
Eletrodos de cobre , Níquel e zinco , Redução de CO2