Influência de aditivos na síntese hidrotermal de nanopartículas de Co3O4 para aplicações em evolução de hidrogênio

Abstract

Reducing particle size is a crucial factor in improving catalyst performance, as well as the presence of persistent defects or foreign species, since the physical properties of these materials are closely related to the presence of these foreign species in their crystal structure, shape, morphology and size of their crystals. However, it is difficult to introduce defects in ultrafine catalysts due to the surface tension and self-purification effect of nanoparticles. In this context, Co3O4 nanoparticles were synthesized together with chemical additives such as urea, ethylene glycol, hydrogen peroxide, among others, using the hydrothermal chemical route, in order to evaluate the impact that these impurities have on the structural and morphological behavior of these nanoparticles. The synthesized nanomaterials were characterized by thermogravimetric analysis, X-ray diffraction, Fourier transform infrared vibrational spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) and electrocatalysis tests to evaluate the hydrogen and oxygen evolution reactions. Through the tests, samples such as those synthesized with sodium borohydride and SDS, for example, showed a reduction in the second band gap, which indicates a greater favorability for electronic transitions, suggesting an increase in the photocatalytic and electrocatalytic activity of these samples.