Site-Specific Controlled Growth of Coiled Lambda-Shaped Carbon Nanofibers for Potential Application in Catalyst Support and Nanoelectronics

Abstract

structure with chiral sub-components for experimental and application use as in site-specific growth of branched CNFs for nanoelectronics or local presentation of catalysts. MAIN TEXTCarbon nanotubes and -fibers can be grown in different types and shapes. [1][2][3][4] Branched carbon nanotubes (CNTs), i.e. structures such as Y-shapes, are of high interest due to their potential use in the field of nano-electrical devices. [4][5][6] Additionally, Y-shaped CNTs or carbon nanofibers (CNFs) can be used for mimicking hierarchical nanostructures found in nature, such as the nanostructures at the toes of Geckos, 7-9 enabling their climbing ability. CNTs and CNFs without branches are still used for mimicking the nanostructures of geckos for their use as dry adhesives, 10-14 but branched CNFs could potentially mimick structures more closely. Finally, the use of CNFs as catalyst support gathered high interest for improvement of catalytic activity. [15][16][17][18] Several approaches were presented to fabricate branched CNTs or CNFs. 5,19,28,29,[20][21][22][23][24][25][26][27] Another peculiar subset of carbon structures are wound-up CNFs/CNTs. These twisted structures are commonly referred to as coiled or helical CNFs/CNTs and are of particular interest for introducing chirality into the system. 4,[30][31][32][33][34][35] They found applications e.g. as highly efficient adsorbent for wastewater treatment. 36 While progress has been made on the bulk production of coiled CNFs, 4,33,37 despite the richness of approaches and obtained carbon structures, the growth of single CNT/CNF based nanostructures on defined positions and tuning their shape is still a tremendous challenge. In a previous study, we discovered a growths mode for lambda shaped CNFs (labelled ΛCNFs or λCNFs, dependent on their geometry) with two feet anchored to the growing substrate and optional a free standing head. 29 These nanostructures grow in an open