Structural and catalytic properties of Ni–Co spinel and its composites

Abstract

Pure nickel-cobalt (Ni-Co) spinel and its two composites with active carbon and multi-walled carbon nanotubes (MWCNTs) were synthesized. X-ray diffraction confirmed the nickel cobaltites of cubic syngony and lattice constants for nanosized crystallites. Fourier transform infrared spectra confirmed an inverse spinel consisting of a tetrahedral site Co 2+ and octahedral sites Ni 2+ and Co 2+. Scanning electron microscopy images demonstrated a surface texture typical for spinels and agglomerates of composite particles with active carbon and MWCNTs. All the synthesized samples have a surface area and porosity that are sufficient for the flow of heterogeneous catalytic processes. The micropore volume of the composite with MWCNTs constituted only 4% of the total porosity, while this percentage represented 25% for the composite on the basis of active carbon. The high catalytic activity of Ni-Co spinel is proved in the model reaction of borohydride hydrolysis. To create composite spinel catalysts, active carbon showed itself to be a more efficient carrier for the catalytically active mass of spinel, as compared to MWCNTs.

Exploring the optical and electrical characteristics of CuO/CuCo2O4 composites

“…If only the Co 3+ ions had been observed at the B site, the octahedral band would have been single. Similar results were observed in the nickel cobaltite system fabricated by using a co-precipitation route [47]. The previous findings confirm migration of some Cu 2+ ions from B to A-site with the speculated formula as following:…”

Enhanced Electrochemical Properties and OER Performances by Cu Substitution in NiCo2O4 Spinel Structure

“…Conversely, if M atoms occupy half of the 16B sites, while Co atoms occupy the 8A sites and the left half of the 16B sites, then the structure is named inverse spinel. Therefore, it can be said that NiCo 2 O 4 has a typical inverse spinel structure [ 28 ]. Here, if a part of the Ni metal is replaced with Cu 2+ ions, the Cu 2+ ions do not occupy the Ni 2+ sites, but are substituted at the tetrahedral sites of Co 2+ , and the Co ions occupying the tetrahedral sites move to the octahedral sites of the empty Ni 3+ [ 29 ].…”

Cathode Material Designing and Characterization: Co3O4/N‐doped Porous Carbon for Asymmetric Supercapacitors

“…Co‐MOF has a sharp XRD pattern with peaks at 17.51°, 18.72°, and 27.11°, which is consistent with previous reports confirming its formation [39,40] . The XRD of Co 3 O 4 /N‐PC shows peaks at 19.0°, 31.2°, 36.7°, 44.7°, 59.1°, and 65.3° for Co 3 O 4 (#ICDD 00–043‐1003) corresponding to the cubic (111), (220), (311), (400), (511) and (440) planes, respectively, as well as peaks for carbon (#ICDD 0000–026‐1077) at 26.8° and 43.0° are attributed to (005) and (101) planes, respectively [41] . The calculated structural cell parameters are shown in Table 1.…”