Synthesis of shape-controllable cobalt nanoparticles and their shape-dependent performance in glycerol hydrogenolysis

Abstract

Cobalt nanorods were synthesized in polyol with using Ir as the nucleation agent and sodium stearate as the surfactant. The aspect ratio of rods can be facilely mediated by Ir/Co molar ratios. During rod growth, the solid cobalt alkoxide and stearate intermediates formed at initial stages and acted as the reservoir to control Co 2+ reduction, followed by further mediating the rod growth. Stearate played the critical role in controlling the formation of rods by its selective and covalent coating on {10-10} planes, which induces the anisotropic growth through [0002] direction. The cobalt rods presented hcp phase in the center part and fcc phase in the conical tips because of growth rate difference in stages, showing the hybrid crystallographic property. The slow growth can also induce the formation of fcc spheres by altering the alkali amount in polyol. In glycerol hydrogenolysis, the hcp rods with the mainly exposed {10-10} planes revealed much higher activity and 1,3-propanediol selectivity than the fcc spheres, demonstrating the facet-dependent performance as solid catalyst. To our knowledge, this is the first example for producing 1,3-propanediol by using facet effect of cobalt nanomaterials. Nano-metal materials with different sizes and shapes showed recently the significant applications in catalysis, selective sensing and optical performance. [1][2][3][4] Among those, cobalt nanomaterials with well defined geometries gained considerable attention owing to its applications in high density data storage [5] , magnetic separation [6] and heterogeneous catalysis [7,8] . Generally, these cobalt nanomaterials possess different crystallographic planes and relatively discrete energy band, both of which show the distinct ability to absorb/activate reactant molecule and mediate their catalytic performance. On the other hand, the shape of cobalt nanomaterials presents orientation effect along exotic magnetic field, thus altering the magnetic properties. Comparing to the spherical nanoparticles, the one-dimensional cobalt nanowires showed the significantly enhanced magnetic performance with larger coercivity and higher blocking temperature. [9] Interestingly, the cobalt nanoparticles with larger sizes possessed higher activity and C 5+ hydrocarbons selectivity in Fischer-Tropsch Synthesis. [10] Moreover, due to the mainly exposed {100} planes of cobalt nanocubes, the activity was comparable to the spherical cobalt which is mainly exposed {111} planes, but the selectivity for C 10+ hydrocarbons was much higher than the latter one, demonstrating the facet-dependent catalytic performance. [11,12] Large numbers of strategies were employed to synthesize cobalt nanomaterials with well defined geometries. By using ordered mesoporous SiO 2 , ZrO 2 , carbon nanotube, polystyrene as the hard templates, [13][14][15][16] and polyvinylpyrrolidone (PVP), cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfonate (SDS) as the soft templates, [17][18][19] cobalt nanowires, nanocubes and hollow spheres can be synthesized. In the pre...

Synthesis of cobalt nanodumbbells and their thermal stability under H2, H2/CO and O2 atmospheres

“…However, in both cases it would have been interesting to monitor the size/shape of the nanorods after the different thermal treatments and reaction in order to discard shape changes (if any) and a misinterpretation of the results. The Co 0 -hcp nanorods with mainly {10-10} planes exposed have been investigated in the glycerol hydrogenolysis and found to be more active than Co 0 -fcc spheres, demonstrating the facet-dependent performance [28]. The authors showed TEM micrographs of spent cobalt materials and observed that the surface of the rods became rough although their 1D shape was retained, evidencing the robustness of the materials dispersed in a 10 % glycerol solution under 200 °C and 3.0 MPa of H 2 for 16 h.…”

“…Figure 1 shows TEM micrograph of the as synthesised cobalt nanoparticles. These nanoparticles have been described previously as hexagonal rods with two conical heads (dumbbell-shaped) [28,34,35] with length of 68±12 nm and diameter of the ends (28±3 nm)…”

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

“…The crystallite sizes calculated from the (10-10), (0002) and (10)(11) line broadening in the Co 50 @(Co 0.5 Sb 0.5 ) 50 sample that was annealed at different temperatures are shown in figure 7. The corresponding XRD patterns are provided in the supplementary information (Fig.…”

“…(b) Evolution of the (0002) and (10-10) crystallite sizes of the hcp Co and (10-11),(10)(11)(12) and(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) crystallite sizes of the β-CoSb as a function of the Sb content.…”

Nanomedicine in Central Nervous System (CNS) Disorders: A Present and Future Prospective

“…54 Easy functionalization property and good biocompatibility of modified molecule are the key requirements to select an effective route for prepare different sized NP. 55 Drug delivery through gold nanoparticles (AuNP) gives a versatile platform for effective drug delivery. Doxorubicin coated AuNP have reported making enhanced drug accumulation by overcoming multidrug resistance (MDR) in cancer treatment.…”