Co@CoSb Core–Shell Nanorods: From Chemical Coating at the Nanoscale to Macroscopic Consolidation

Abstract

Core-shell magnetic anisotropic particles were prepared by reduction of Sb acetate at the surface of cobalt nanorods dispersed in a solution consisting of 1,2 tetradecanediol in oleylamine. X-ray diffraction and local EDS analyses revealed a thin β-CoSb shell with a controlled thickness ranging from 5 to 15 nm that depended on the Sb/Co molar ratio and the reduction temperature. The shell completely coats the rod surface but does not alter the shape anisotropy or the hcp structure of the cobalt cores, and the hard magnetic properties are preserved after coating with a coercivity higher than 3 kOe. Consolidated nanostructured materials that exhibit properties of permanent magnets were prepared by compaction of the core-shell Co@CoSb nanorods. The thin CoSb shell was very efficient for preventing the cobalt anisotropic core from sintering at high temperatures (up to 300°C) and high pressures (up to 1.5 GPa). These results indicate that the bottom-up approach is very promising for preparation of nanostructured hard magnetic materials.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

“…Not reported yet [39] Cu@Ni core-shell NWs / 3 Epitaxial growth of Ni shell onto Cu NWs Not reported therein [50] Fe 3 O 4 @RF@void@mSiO 2 yolk-shell MNCs / 4b Plasmolysis-inspired nanoengineering strategy Catalytic hydrogenation of 4-nitrophenol [79] Ni@void@SnO 2 yolk-shell MNCs / 4c Acid etching hydrothermal method Outstanding electromagnetic wave absorption [94] Fe 3 O 4 @SiO 2 core-shell MNCs / 5a Water-in-oil microemulsion Magnetic particle imaging (MPI) [99] Amine-functionalized Fe 2 O 3 -SiO 2 core-shell MNCs / 6 Three-step process Biomedicine (envisaged) [ 114] Fe 3 O 4 @C MNCs / 7a Solvothermal process Several applications [ 141] Au-Fe 3 O 4 heterostructures / 8a Growth of Fe 3 O 4 in the presence of Au seeds Biomedicine (envisaged) [ 185] Ag-Pt-Fe 3 O 4 heterotrimers / 8b Total-synthesis framework (seeds-based) Several applications [ 188] Fe 2 O 3 -based MNCs / 9 Ligand exchange and click chemistry Not reported [ 243] Au/Fe x O y -thiol, catechol Janus particles / 10 Multi-step process Biological applications, MRI [ 264] [RuCl(CO 3 )(𝜇-DOPA)]@maghemite MNCs / 11 Multi-step process CO release [ 270] NCMTs@Fe 3 O 4 @SiO 2 @C/Ni MNCs / 12 Multi-step process 4-NP catalytic reduction [ 320] HAP@Fe 3 O 4 @PDMS paper /13 Multi-step process Oil/water separation-wastewater treatment [ 368] Tea waste/Fe 3 O 4 MNCs / 14 Co-precipitation Cr(VI) removal [ 370] Fe 3 O 4 @SiO 2 @Ag MNCs / 15 Multi-step process Thiram pesticide detection [ 415] GR-Fe 3 O 4 -PEDOT-Au MNCs / 16a Multi-step process Penicillin detection [ 419] Au@MWCNTs-Fe 3 O4-PtTi / 16b Multi-step process Streptomycin detection [ 429] MBCPE/Fe 3 O 4 @Ag MNCs / 17 Multi-step process DNA detection [ 421] Au/Fe 3 O 4 /MoS 2 CAs MNCs / 18 Multi-step process Hg(II) detection [ 427] FeCo/GC MNCs / 19 Methane CVD MRI [ 124] SPION-PEG-based MNCs / 20 Therm. Decomp.…”

Core–shell nanostructures for better thermoelectrics

“…56 These core-shell structures possess multifunctional properties through integrating two different materials into one entity. Therefore, they are widely studied and used in various applications such as catalysis, [58][59][60][61][62][63] electronics, 64,65 biomedical applications, [66][67][68] photoluminescence, [69][70][71][72] sensors, 73 piezo-electrics, 74,75 magnetic applications, [76][77][78] energy storage, 79,80 solar cells, [81][82][83] and CO 2 capture. [84][85][86] Core-shell materials offer additional electronic modifications due to band-edge alignment at the interface between the core and shell.…”

From soft chemistry to 2D and 3D nanowire arrays with hard magnetic properties and permanent magnet applications

“…It was observed for example, that the Co NRs encapsulation with a thin carbon layer via treatment in organic solvents enhanced their thermal stability [54]. For compaction at high pressures, a thin layer of CoSb alloy was grown at the surface of cobalt nanorods by reduction of Sb acetate dispersed in a solution consisting of 1,2-tetradecanediol in oleylamine [55]. Figure 24 shows an example of a magnet prepared by compaction of core-shell Co@CoSb nanorods.…”

“…This value is lower than the energy product of aligned nanorods. An improvement in this value would require a better alignment of the Co@CoSb rods to increase the Mr/Ms and the squareness of the magnetization curve [55]. The issue of misalignment in the compacted materials was partially addressed by consolidations of pre-aligned cobalt rods pellets like those shown on Figure 25a.…”