Understanding the growth mechanism of single-walled carbon nanotubes (SWCNTs) and achieving selective growth requires insights into the catalyst structure-function relationship. Using an in situ aberration-corrected environmental transmission electron microscope, we reveal the effects of the state and structure of catalysts on the growth modes of SWCNTs. SWCNTs grown from molten catalysts via a vapor-liquid-solid process generally present similar diameters to those of the catalysts, indicating a size correlation between nanotubes and catalysts. However, SWCNTs grown from solid catalysts via a vapor-solid-solid process always have smaller diameters than the catalysts, namely, an independent relationship between their sizes. The diameter distribution of SWCNTs grown from crystalline Co 7 W 6 , which has a unique atomic arrangement, is discrete. In contrast, nanotubes obtained from crystalline Co are randomly dispersed. The different growth modes are linked to the distinct chiral selectivity of SWCNTs grown on intermetallic and monometallic catalysts. These findings will enable rational design of catalysts for chirality-controlled SWCNTs growth.
technology, photoelectric devices, life science, energy conversion, and storage materials due to their strong physical and chemical properties. [1][2][3][4] Since the discovery of CNTs by Iijima in 1991, [5] researchers have carried out a lot of efforts to improve the synthesis process and performance characterization, as well as exploring the mechanism. At present, dozens of methods have been utilized to synthesize carbon nanostructures. [6][7][8] Studies have shown that catalysts, such Fe, Co, Ni, are significant in the growth process of carbon nanostructures, growth mode, e.g., basegrowth and tip-growth. [9][10][11][12][13][14][15][16][17] And during the growth process, the interface plays crucial roles in regulating the carbon nanostructures nucleation thermodynamics and growth kinetics, [18] ultimately governing the carbon material structure, such as GSs, [19] CNTs, [20][21][22][23] carbon nanofiber, [24] carbon hemispheres, [25] Janus structure, [26] and even controlling the carbon nanotube chirality distribution. At the same time, the catalyst particle size, external electric field, and the interaction force of the substrate contacted with the catalyst also affect the growth of carbon nanostructure. [27,28] For example, Gohier et. al. reported that the growth mode switches from "tip-growth" for large particles to "base-growth" for smaller ones with the catalysts of cobalt, nickel, and iron. [13] Saeidi presented the effect of interaction between AC electric field and metal cluster sitting at tip end of the CNT on tipgrowth of CNT in CVD theoretically. [28] He et. al. revealed the Co-MgO catalyst affords the tip-growth mode of CNTs growth, indicating a weak metal-support interaction, while the Co-SiO 2 catalyzes the CNTs growth by a base-growth mode. [12] Despite great progress in achieving different structure of carbon nanostructures, how the interface interaction affects controllable synthesis of carbon nanostructures still needs to be deeply revealed with in situ investigations.Aberration-corrected environmental transmission electron microscopy (ETEM) has the advantage of direct, real-time, and high resolution to characterize the materials and evolution process. [29][30][31][32][33][34] It has been used to take in situ images of catalyst and carbon nanostructures with high temporal and spatial resolution. Moreover, it is an effective method to study the evolution process of catalyst NPs and further elucidate the mechanism of nucleation and growth process of carbon nanostructures. [35][36][37][38][39][40][41][42] Controllable synthesis of carbon nanostructures is expected to achieve high electrical, optical, and mechanical performance for various applications. Despite great progress in this field, controllable synthesis of carbon nanostructures, i.e., graphite shells (GSs) and carbon nanotubes (CNTs), is still demanded to be deeply revealed. Here, a strategy is demonstrated to achieve GSs and bamboo CNTs by regulating the interface interaction via in situ pyrolysis of Co phthalocyanine (CoPc) in an enviro...
By heating cobalt phthalocyanine (CoPc), bearing the dual roles of supplying carbon atoms and metamorphosizing a graphitization‐catalyst, the time‐evolution of CoPc to an intriguing Co‐Co3C nano‐core enveloped by several graphitic layers are tracked, and out‐diffusion of carbon atoms from the core to fuel the growth of new outermost shell‐layers. More details can be found in article number 2001112 by Rongming Wang, Woon‐Ming Lau, and co‐workers.
Fe-doped NiS2 with different doping contents was one-pot synthesized through a solvothermal process utilizing a PEGylated deep eutectic solvent. The prepared samples could be used for efficient and stable oxygen evolution electrocatalysis.
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