Suchergebnisse

A major challenge to turn the potential of carbon nanotubes (CNTs) into customer applications is to reduce or eliminate their toxicity. Taking into account health and safety concerns, intensified research efforts have been conducted to improve the biocompatibility of CNTs, including the development of new shortening and purification strategies. Ideally, the methods used for improving the biocompatibility of CNTs should not alter the electronic properties of CNTs. Herein, we report on the shortening of a sample containing single-walled and double-walled CNTs using steam and obtain new insights in the properties of the steam-treated CNTs. The present study shows that short CNTs (median length ca. 200 nm) can be obtained under the reported conditions. Raman analysis reveals that wider and outer nanotubes undergo more significant changes than the narrower and inner ones, especially after a prolonged steam treatment. ; The research leading to these results has received fundingfrom the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007–2013/under REA grant agreement n8 290023 (RADDEL). ICN2 ac-knowledgessupport from the Severo OchoaProgram(MINECO, Grant SEV-2013-0295), and M. Kalbacthe support from MSMTproject LL1301. M. Kierkowicz and E. Pach are enrolled in the PhD Program in Materials Science at UAB. ; Peer reviewed

Raman spectroscopy is undoubtedly the most frequently used technique for universal characterization of graphene and related materials. Quantification of parameters like disorder or strain is possible through analysis of particular Raman bands. However, under certain conditions, such evaluation can be jeopardized by—sometimes hidden—convolution of more overlapping effects. In this work, graphene functionalization by the common nitrobenzenediazonium salt under simultaneous biaxial tensile deformation induced by substrate swelling was investigated by Raman spectroscopy. As expected, the disorder-related D band appeared in the spectra documenting the covalent attack on the graphene lattice. However, the strain-induced shift of the graphene bands exposed additional peaks, masked at exactly the same positions as the unstrained graphene bands. The new bands were assigned to vibrations of the diazonium molecule and its decomposition products adsorbed on top of the functionalized graphene. The external strain thus provided means for more correct quantification of the lattice disorder. ; This work was funded by Czech Science Foundation (GACR 17-18702 S). We also acknowledge the support from the European Regional Development Fund; OP RDE; Project: "Carbon allotropes with rationalized nanointerfaces and nanolinks for environmental and biomedical applications" (No. CZ.02.1.01/0.0/0.0/16_026/0008382). This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic and The European Union - European Structural and Investments Funds in the frame of Operational Programme Research Development and Education - project Pro-NanoEnviCz (Project No. CZ.02.1.01/0.0/0.0/16_013/0001821). ; Peer reviewed