Spectroscopic and Morphological Investigation of Co₃O₄Microfibers Produced by Electrospinning Process

Abstract

The Co oxide microfibers were synthesized using the electrospinning process and formed Co 3 O 4 microfibers after being calcined at high temperatures. The calcination temperature influenced the diameters, morphology, crystalline phase, and chemical environment of the fibers. The surface morphology of the obtained fibers was examined by using the scanning electron microscope (SEM). As the calcination temperatures increased from room temperature to 873 and 1173 K, the diameters of the cobalt oxide fibers decreased from 1.79 to 0.82 and 0.32 mm, respectively. The structure of the fibers was investigated with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The calcined Co 3 O 4 fibers had crystalline face-centered cubic (fcc) structure. The X-ray photoelectron spectroscopy (XPS) results revealed that increasing the calcination temperature promoted the formation of Co 2+ and Co 3+ species.

Formic Acid Modified Co3O4-CeO2 Catalysts for CO Oxidation

“…As shown in Figure 6A-C, for the Co 2p spectra, there is a main peak at 779.9 eV, which can be assigned to the species of Co 2+ and Co 3+ [18], while the satellite peak at 782.2 eV can be attributed to the Co 2+ species [19], suggesting that the Co species mainly exist as Co 3 O 4 , and this is consistent with the results from XRD. In Figure 6D,E for Ce 3d spectra, the peaks near 882.5 eV, 898.1 eV, 901.0 eV, and 916.5 eV can be attributed to Ce 3+ of Ce 3d 5/2 , while the peaks near 888.0 eV and 906.8 eV can be attributed to Ce 4+ of Ce 3d 3/2 [20,21] …”

“…As shown in Figure 6A-C, for the Co 2p spectra, there is a main peak at 779.9 eV, which can be assigned to the species of Co 2+ and Co 3+ [18], while the satellite peak at 782.2 eV can be attributed to the Co 2+ species [19], suggesting that the Co species mainly exist as Co3O4, and this is consistent with the results from XRD. In Figure 100 200 300 400 500 600 …”

Environment friendly hydrothermal synthesis of carbon–Co3O4 nanorods composite as an efficient catalyst for oxygen evolution reaction

“…The peak at 531.13 eV corresponds to organic C-O bond. The other peak at 234.07 eV is associated with the water absorbed onto the surface of the Co 3 O 4 nanorods [40] .…”

Doping cobalt hydroxide nanowires for better supercapacitor performance

“…2b. From the fitting of the high-resolution spectrum of the 2p 2/3 peak, the oxidation states of cobalt can be determined [30][31][32]. For pure cobalt hydroxide sample, a single peak centered $780.5 eV can be fitted to the spectrum, indicating an oxidation state of Co 2+ , as shown in Fig.…”