Amines as dual function ligands in the two-phase synthesis of stable AuxCu(1−x) binary nanoalloys

Abstract

The synthesis of Au x Cu (1Àx) nanoalloys (NAs) by a two-phase method employing amines acting simultaneously as coordinating ligands, phase transfer agents as well as nanoparticle (NP) stabilisers, is presented. The value of x was varied between 0 and 1 and dodecylamine (DDA) and hexadecylamine (HDA) were used as ligands. The nanoparticles were characterised by elemental analysis, UV-vis and IR spectroscopies, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning TEM (STEM) and X-ray photoelectron spectroscopy (XPS). Alloying with Au imparts significant stability to Cu nanoparticles. Interestingly, some degree of surface segregation for Cu in the synthesised Au x Cu (1Àx) NAs is revealed from the TEM analysis, contrary to expectations based on previously calculated segregation energies. XRD analysis demonstrates a high degree of crystallinity of the cores although the crystallite sizes obtained from the Scherrer equation are smaller than TEM measurements. A mild heat treatment is sufficient to enhance the overall particle crystallinity resulting in crystallite size estimates from XRD comparable to those obtained from TEM.

Assessing the Electrochemical Stability Window of NASICON-Type Solid Electrolytes

“…Selected area electron diffraction (SAED) measurements confirmed the crystalline nature of Au and LAGP particles. The selected patterns show interplanar spacings of 2.36 Å for Au-(111) (Dilshad et al, 2012) and 3 S4A,B). Very few cavities are observed between the grains (except the ones created by the ion beam), confirming the good sintering of the particles.…”

Correlation between surface chemistry and magnetism in iron nanoparticles

“…When exposed to a hydrogen atmosphere, amido complexes are expected to release the corresponding amine in the course of the reaction, a class of ligands oen used in NPs synthesis and stabilization. [10][11][12][13] Contrarily coordination of amido ligands at the surface of NPs was only seldom discussed. 36 Here, DFT calculations showed that: (1) adsorption of the diphenylamido ligand is signicantly more favourable on the iron surface than that of DPA, (2) adsorption of the bis(trimethylsilyl) amido ligand is only slightly more favoured than that of HMDS and (3) adsorption energies of all amines are comparable.…”

“…When exposed to an hydrogen atmosphere, amido complexes are expected to release the corresponding amine in the course of the reaction, a type of ligand oen used to control the stability and morphology of NPs in colloidal solutions. [10][11][12][13] [Fe(N(SiMe 3 ) 2 ) 2 ] 2 has been reported by our group and others to afford iron NPs of controlled size and shape, and deprived of any surface oxidation, affording systems particularly adapted to investigate surface magnetism at the nanoscale. [14][15][16][17][18][19] Surface effects are best observed on NPs which display a high enough proportion of surface atoms, namely those having a size below 3 nm.…”

Template-less and surfactant-free solvent-driven direct synthesis of urchin-like gold nanoparticles in anisole

“…It is possible that with hexadecylamine and PVP, complexes of Au 3+ were formed in solution. Nitrogen ligand coordination compounds of Au 3+ have not been studied extensively [48]. Nagel and Beck [49] have reported that the reaction of AuCl 4 with n-butylamine led to the formation of the imine ClAuNH=R, by a ligand displacement reaction.…”