Thermal Strategy Optimization for Tailored Cobalt Oxide Nanofibers: Composition and Morphology Control

Abstract

This study investigates the effect of thermal treatment on the composition and morphology of cobalt oxide nanofibers synthesized via electrospinning. Cobalt acetate tetrahydrate and poly (vinyl alcohol) were used as precursors to produce cobalt acetate/poly(vinyl alcohol) nanofiber mats. The electrospun mats were subjected to various thermal treatments, including calcination in air at 500[Formula: see text]C, calcination under argon at 700[Formula: see text]C and 850[Formula: see text]C and treatment with water gas (CO and H[Formula: see text] at 180[Formula: see text]C. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were employed to characterize the nanofibers. The results demonstrated that the polycondensation tendency of cobalt acetate and the supportive properties of poly(vinyl alcohol) led to the maintenance of nanofibrous morphology across all thermal treatments. Calcination in air produced dense, highly crystalline Co 3 O 4 nanofibers. In contrast, calcination under argon at 700[Formula: see text]C resulted in an amorphous carbon matrix embedded with small cobalt-based nanoparticles, while at 850[Formula: see text]C, the nanofibers contained larger, highly crystalline cobalt nanoparticles. Thermal treatment with water gas transformed the nanofibers into nano-belts primarily composed of crystalline CoO and Co 3 O 4 , with minimal amorphous phase. This study highlights the critical influence of thermal treatment on the structural and compositional properties of cobalt-based nanofibers, offering insights for tailoring these materials for applications in catalysis, energy storage and electronic devices. The findings emphasize the potential of controlled thermal strategies to produce diverse cobalt-based nanostructures with distinct properties.