Reversible Attachment of Platinum Alloy Nanoparticles to Nonfunctionalized Carbon Nanotubes

Abstract

The formation of monodisperse, tunable sized, alloyed nanoparticles of Ni, Co, or Fe with Pt and pure Pt nanoparticles attached to carbon nanotubes has been investigated. Following homogeneous nucleation, nanoparticles attach directly to non-functionalized singlewall and multiwall carbon nanotubes during nanoparticle synthesis as a function of ligand nature and the nanoparticle work function. These ligands do not only provide a way to tune the chemical composition, size and shape of the nanoparticles but also control a strong reversible interaction with carbon nanotubes and permit controlling the nanoparticle coverage. Raman spectroscopy reveals that the sp2 hybridization of the carbon lattice is not modified by the attachment. In order to better understand the interaction between the directly attached nanoparticles and the non-functionalized carbon nanotubes we employed first-principles calculations on model systems of small Pt clusters and both zig-zag and armchair singlewall carbon nanotubes. The detailed comprehension of such systems is of major importance since they find applications in catalysis and energy storage.Composites of metallic nanoparticles (NPs) and carbon nanotubes (CNTs) exhibit high catalytic activity for various chemical reactions [1][2][3][4][5][6] and have also been explored for hydrogen storage applications [7]. Recent reports include platinum [6,8,9] [19,20] and catalytic properties [21][22][23]. Beyond that, 1D alignment of NPs enables to modify the saturation magnetization and coercitivity through magnetostatic coupling [24][25][26]. A convenient way for 1D alignment is the attachment of NPs to CNTs, which is usually achieved by electrochemical deposition [27,28], the reduction of metallic salts in the presence of functionalized CNTs [15,29], or chemical vapor deposition [10], among others [30]. On the other hand, concerning the NP synthesis, the organometallic synthesis route provides nanocrystalline alloyed materials with precise size control and tunable composition in several systems [20,31,32]. Here, we report on the synthesis of alloyed N i x P t 1−x [20], Co x P t 1−x and F e x P t 1−x [32] NPs as well as pure P t [33] NPs and their attachment to non-functionalized singlewall (SWCNTs), multiwall carbon nanotubes (MWCNTs) and glassy carbon by their simple integration in the organometallic synthesis. The experimental procedure involves only a single synthetic step, whereby the crucial parameter for attachment was found in the correct balance of the ligands oleylamine (OA) and oleic acid (Oac).

Attachment of Colloidal Nanoparticles to Boron Nitride Nanotubes

“…Performing the ZnO synthesis at 115 °C resulted in BNNTs which are fully covered, as shown in Figure 3d These results show that it is possible to produce composites of BNNTs with attached PbSe, CdSe, or ZnO NPs by the same approach using oleate. To further investigate possibilities and limitations of NP-BNNT composite formation, we examined the transferability of the methods for the semiconducting NP-CNT composite formation developed in previous work 15,25 and the attachment of metal NPs 26 to BNNTs.…”

Attachment of Iron Oxide Nanoparticles to Carbon Nanotubes and the Consequences for Catalysis

“…[24][25][26] Carbon nanotube (CNT) supports are of growingi nteresti nr esearch owing to their chemical inertness and mesoporosity. [35][36][37][38] In the present work, the impact of carbon surface oxidation on the attachment of colloidal iron-oxide nanoparticles (Fe-NPs) to CNTsa nd their subsequentp romotion with Na + Sw as investigated. [30][31][32][33][34] The attachment of colloidal particles to support materials has so far not been researched abundantly;h owever,i th as been found that the support material can alter the behavior of the particlesd uring catalysis.…”

“…[30][31][32][33][34] The attachment of colloidal particles to support materials has so far not been researched abundantly;h owever,i th as been found that the support material can alter the behavior of the particlesd uring catalysis. [35][36][37][38] In the present work, the impact of carbon surface oxidation on the attachment of colloidal iron-oxide nanoparticles (Fe-NPs) to CNTsa nd their subsequentp romotion with Na + Sw as investigated. It was found that functionalizing the CNT support by oxidation (CNT-Ox) impeded attachment of the colloidal particles and led to the growth of the nanoparticles, which decreased the catalytic activity.T his showed that functionalization of the support is not alwaysbeneficial and can have adetrimental effect if colloidal particlesa re used.…”

Synthesis of Single-Walled Carbon Nanotube−Nanoparticle Hybrid Structures

“…Other surfactants such as oleylamine and oleic acid were used to synthesize SWNT-CoPt nanoparticle systems by coordination in a one pot-synthesis method (38). Although oleylamine was essential for the formation of stable Pt alloy nanoparticles, addition of excess oleylamine (>0.15mmol) to a sample with a high coverage of nanoparticles resulted in spontaneous detachment of the nanoparticles from the nanotubes.…”