Shape Control of Platinum Nanoparticles

Abstract

The synthesis of shape controlled platinum nanoparticles has been investigated through an organometallic approach starting from the complex Pt2(dba)3 and using a long alkyl chain amine, hexadecylamine (HDA), as stabilizer. The influence of the experimental parameters (reactive gas and solvent nature, stabilizer/metal ratio, reactants concentration, temperature) on the shape of the Pt nanoparticles has been studied. Various shaped platinum nanostructures such as isolated nanoparticles, dendrites or crystalline nanowires were obtained, depending on the reaction conditions. This method takes profit of the mild conditions of chemistry in solution and allows obtaining regular nanostructures, most of them being homogeneous in shape as well as in size (isolated nanoparticles) or diameter/length (nanowires). Transmission electron microscopy and wide‐angle X‐ray scattering were used as characterization techniques. Beside the Knight‐shift effect of platinum, NMR solution investigations clearly evidenced the coordination of the amine at the Pt particles surface and its mobility. This mobility, increased when H2 is used as reactive gas for the precursor decomposition, favors the particles coalescence into nanowires. This phenomenon is also favored by the “soft” template character of the amine in particular in toluene solution.

Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts

“…Indeed, as expected from previous works 7,23a the IR spectrum of such NPs, recorded immediately after the synthesis, presented two characteristic bands for COt and COb at 2041 and 1859 cm –1 , respectively which remained essentially unchanged when these are exposed to CO (see ESI, Fig. S24†).…”

Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts

“…Indeed, as expected from previous works 7,23a the IR spectrum of such NPs, recorded immediately after the synthesis, presented two characteristic bands for COt and COb at 2041 and 1859 cm –1 , respectively which remained essentially unchanged when these are exposed to CO (see ESI, Fig. S24†).…”

Solution synthesis of antiferromagnetic manganese nanoparticles

“…The absence of resonance for isolated Mn@HDA results from the slow tumbling of the NPs in solution, as previously observed for Ru and Pt NPs 28,29 and may also be enhanced in this case by the magnetic properties of the Mn NPs. When adding 1 and 2 equiv.…”

Organometallic Nanoparticles Ligated by NHCs: Synthesis, Surface Chemistry and Ligand Effects

“…Therefore, as the size of the particles decreased, the CO signal was shifted to a lower frequency, being almost suppressed when the size was ca. 1.2 nm (Figure 11b), as previously observed in analogous smaller Pt [80,81] and RuPt [82] systems. The coordination of the NHC ligand on Pd NPs was also proved by the observation of Knight shift in the carbenic carbon by Asensio et al [57].…”

Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts

“…Indeed, as expected from previous works 7,23a the IR spectrum of such NPs, recorded immediately after the synthesis, presented two characteristic bands for COt and COb at 2041 and 1859 cm –1 , respectively which remained essentially unchanged when these are exposed to CO (see ESI, Fig. S24†).…”

Solution synthesis of antiferromagnetic manganese nanoparticles

“…The absence of resonance for isolated Mn@HDA results from the slow tumbling of the NPs in solution, as previously observed for Ru and Pt NPs 28,29 and may also be enhanced in this case by the magnetic properties of the Mn NPs. When adding 1 and 2 equiv.…”

Organometallic Nanoparticles Ligated by NHCs: Synthesis, Surface Chemistry and Ligand Effects

“…Therefore, as the size of the particles decreased, the CO signal was shifted to a lower frequency, being almost suppressed when the size was ca. 1.2 nm (Figure 11b), as previously observed in analogous smaller Pt [80,81] and RuPt [82] systems. The coordination of the NHC ligand on Pd NPs was also proved by the observation of Knight shift in the carbenic carbon by Asensio et al [57].…”

Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts

“…Indeed, as expected from previous works 7,23a the IR spectrum of such NPs, recorded immediately after the synthesis, presented two characteristic bands for COt and COb at 2041 and 1859 cm –1 , respectively which remained essentially unchanged when these are exposed to CO (see ESI, Fig. S24†).…”

Solution synthesis of antiferromagnetic manganese nanoparticles

“…The absence of resonance for isolated Mn@HDA results from the slow tumbling of the NPs in solution, as previously observed for Ru and Pt NPs 28,29 and may also be enhanced in this case by the magnetic properties of the Mn NPs. When adding 1 and 2 equiv.…”

Organometallic Nanoparticles Ligated by NHCs: Synthesis, Surface Chemistry and Ligand Effects

“…Therefore, as the size of the particles decreased, the CO signal was shifted to a lower frequency, being almost suppressed when the size was ca. 1.2 nm (Figure 11b), as previously observed in analogous smaller Pt [80,81] and RuPt [82] systems. The coordination of the NHC ligand on Pd NPs was also proved by the observation of Knight shift in the carbenic carbon by Asensio et al [57].…”