Solution blow spun Co3O4 nanofibers as electrocatalyst for oxygen evolution processes

Abstract

In this study, Co3O4 nanofibers were produced using the solution blow spinning (SBS) method. The investigation focused on studying their structure, morphology, and electrocatalytic properties in relation to the oxygen evolution reaction (OER) in alkaline solution (KOH). Calcination at 600 °C resulted in Co3O4 fibers without the presence of secondary phases (NF600), while calcined fibers at 400 °C showed a Co3O4–CoO composite phase (NF400), confirmed by XRD. The size of the crystallites, determined through Rietveld refinement analysis of XRD patterns, ranged from 42.6 nm to 56.2 nm for the calcined fibers at 400 °C and 600 °C, respectively, confirming the nanometric scale of the cobalt oxide fibers. Morphological analyses confirmed the production of rough nanofibers with monomodal distribution, with mean diameter of 385 nm for NF600 and 485 nm for NF400. The EDS confirms the presence of the chemical elements of cobalt and oxygen, estimating their abundance in the sample. The XPS analysis showed that the concentration of oxygen vacancies and the presence of species with higher oxidation states (Co3+) were beneficial to improve OER. Nanofibers calcined at 600 °C showed an overpotential of 330 mV at 10 mA cm−2, more efficient Tafel kinetics and low resistance to charge transfer (0.37 Ω) when compared to nanofibers calcined at 400 °C (338 mV). This result demonstrates the competitive catalytic activity of cobalt oxide nanofibers produced by SBS compared to other systems mentioned in the literature. Therefore, this work offers a new perspective on the development of electrocatalysts based on the structure and properties of cobalt oxide electrodes by the SBS method.