Synthesis and evaluation of nickel doped Co3O4 produced through hydrothermal technique

Abstract

The synthesis of undoped cobalt oxide and cobalt oxide with 4%nickel doping is studied in samples obtained through hydrothermal technique. After the final heat treatment at 300°C, X-ray diffraction analysis indicated the formation of cobalt spinel oxide with a complete replacement of nickel in the lattice. An average crystallite size of ~42 nm and ~31nm was found, as well as a particle size of ~ 20 nm and ~30 nm for Co3O4 and Co3-xNixO4, respectively. Structural parameters were established through Rietveld refinement with a good correspondence between the simulated and the experimental pattern with values of x2 = 1.25 and GOF = 0.90 for Co3O4. The energy band gap was found through UV-Vis spectroscopy in two different regions: Eg1 and Eg2 values vary between 1.54 and 2.04eV for samples doped with nickel. The SEM results indicated the formation of nanostructures with semi-cubic shape and irregular rods. Parameters such as crystal size, particle size, surface area, as well as morphology of the final product depend on doping.

Electrical, Magnetic, and Sensing Properties of Acetone in Co3–xNixO4-rGO Samples

“…For the nonannealed samples, the corresponding diffraction patterns can be found in another publication. 28 Both the annealed samples for the sensing pellets and the nonannealed samples exhibit diffraction peaks indicative of the spinel structure of Co 3 O 4 . Additionally, Figure 2 illustrates the diffraction peaks of silver, which was employed to create electrical contacts in the pellet used for the sensing experiments.…”

Analysis and evaluation of structural properties of Co3O4 microparticles obtained at low temperature

“…The synthesis of cobalt oxide compounds with adjustable physicochemical properties has become a recurrent research topic [29]. For the analysis of Co 3 O 4 , the description of the atomic positions in the spinel structure with the general formula AB 2 O 4 depends on the choice of the adjustment for the origin in the space group Fd3m to which most of the spinel compounds belong [30]. Consequently, two different combinations with point symmetries 43m and 3m are possible options for the origin of the unit cell, as observed in Table II with the values obtained for the compound Co 3 O 4 , where the Wyckoff positions indicate the junctions for the various sites of the lattice.…”

Recovery of Arenes from Polyethylene Terephthalate (PET) over a Co/TiO2 Catalyst

“…[30] For the calcined Co/TiO 2 catalyst, additional diffraction peaks appeared at 31.3, 44.8, 59.5, and 65.4°c orresponding to Co 3 O 4 . [31] The peak at 44.3°assigned to metallic Co 0 was noticed for the reduced Co/TiO 2 catalyst. [26b] Of note, the XRD pattern of TiO 2 after calcination and reduction did not change, indicating that the thermal treatments were below the temperature required for the phase transformation of anatase to rutile, which typically started at 600°C.…”