Navegando por Autor "Silva, Vinícius D."

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Role of oxygen vacancies on the energy storage performance of battery-type NiO electrodes
(Elsevier, 2020-05) Paskocimas, Carlos Alberto; Silva, Thayse R.; Silva, Vinícius D.; Ferreira, Luciena S.; Araújo, Allan Jedson Menezes de; Torres, Marco Antonio Morales; Simões, Thiago Araújo; Macedo, Daniel Araújo de
In this study, the influence of the surface oxygen vacancies on the energy storage performance of electrodes based on nickel oxide (NiO) nanoparticles was investigated. NiO samples were synthesized by three facile and low-cost syntheses routes: nitrate calcination, citrate, and combustion methods. The concentration of surface defects in NiO powders was determined using XPS analyses, which showed a higher amount of oxygen vacancies for the sample obtained by nitrate calcination. According to the cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves, NiO-based electrodes were classified as battery-like. CV results suggest that redox reactions are diffusion-controlled processes with a faster diffusion rate for the sample obtained by the nitrate calcination method. This is in accordance with the GCD and electrochemical impedance spectroscopy (EIS) results, with higher specific capacity and higher electrical conductivity (lower equivalent series resistance) for the sample obtained by nitrate calcination. The results indicate that oxygen vacancies play an important role in the electrochemical performance of battery-type NiO electrodes

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