Distinctive electronic structure, unusual magnetic properties and large enhancement in SERS of 1D gallium nanoribbons achieved by doping calix[6]arene

Abstract

The present work provides a novel route for forming one-dimensional (1D) gallium (Ga) nanoribbon materials with a host molecule calix[6]arene (CA-6) as a template by a facile, one-step and low temperature chemical bath method. Field-emission scanning electron microscopy and transmission electron microscopy showed that the uniform 1D Ga nanoribbon material (Ga-a) can be constructed only in the presence of CA-6, and the formation of ribbon structures is highly dependent on doping ratios and deposition times. Our data indicate that the unusual effect of CA-6 is due to a combination of two factors: a high density of OH groups in the outer surface of its cavity and an appropriate cavity diameter. Especially, the uniform 1D Ga nanoribbon material exhibits a distinct electronic structure and very rare magnetic behaviour when compared to those 3D Ga materials obtained by means of other host molecules: calix[4]arene, g-cyclodextrin and 18-crown-6. For example, of all the Ga materials, the uniform 1D nanoribbon material has the lowest electron density of Ga core levels in light of X-ray photoelectron spectroscopy analysis. This result suggests that there is a stronger molecule-atom interaction between Ga atoms and CA-6 molecules compared with those in other host-guest systems. More importantly, the uniform 1D Ga nanoribbon material exhibits a magnetic transformation from a diamagnetic to a paramagnetic state under the influence of an applied field, which is completely different from those of all the 3D Ga materials and all the irregular Ga nanoribbon materials. Such a transformation is novel in metals and particularly useful in the chemistry of materials since it allows dramatic modifications of magnetic properties of metal nanocrystals. Finally, a strong surfaceenhanced Raman scattering of the uniform 1D Ga nanoribbon material has been observed for organic molecules adsorbed on their surface. Taken together, we believe this work opens a new channel for development of 1D metal-based nanomaterials.

Increased Water Solubility of Molybdenum Trioxide Induced by <em>&beta;</em>-Cyclodextrin

“…Our data (see Fig. S10) reveal that the carbon-oxygen stretch, ethylamine 39 Importantly, the intensities of these bands obtained from a silica substrate are much weaker than that with BGP, indicating that BGP has a significant SERS activity for R6G and CV. Such a SERS enhancement can be explained by its small particle size and high specific surface area.…”

Gallium/gold composite microspheres fixed on a silicon substrate for surface enhanced Raman scattering

“…There are many ower patterns in the surface of the microsphere, which was not observed in the surface of Ga microspheres prepared by other methods. 39 The ower patterns may be caused by the uneven surface of the microsphere. The EDX spectrum in Fig.…”

“…There are many flower patterns in the surface of the microsphere, which was not observed in the surface of Ga microspheres prepared by other methods [39]. The inset is the high-magnification SEM image of a single Ga microsphere.…”

“…[34][35][36][37] Many methods including chemical vapour deposition have been developed to fabricate Ga nano-or micro-structures with various morphologies such as nanoparticles, nanoribbons, nano-or micro-spheres. [38][39][40][41] In this work, Ga microspheres partly embedded in Si substrate were prepared by a chemical vapour deposition method and used as a template to fabricate Au nanoparticle-decorated Ga (Ga/Au) composite microspheres. As-prepared Ga/Au composites are suitable for applying in real applications because of the immobilization of Ga/Au microspheres on Si substrate.…”

Vertical silver nanorod growth as a surface-enhanced Raman scattering

“…Various methods for the fabrication of SERS have been reported in the literature [2][3][4] since the structural shapes or the distance between molecules determine its Raman sensitivity. The sensitivity of SERS, thus strongly depends on the shape, size, and periodic array of their materials such as nanoparticles [5,6], nanobelts [7], nanoribbons [8,9], and nanorods [10][11][12][13] due to the change of absorption and scattering rates on surface. The major problem with the sensitivity scaling-up is in the development of fabrication technology for stability and reproducibility of SERS substrates.…”