General Oriented Formation of Carbon Nanotubes from Metal–Organic Frameworks

Abstract

Carbon nanotubes (CNTs) are of great interest for many potential applications because of their extraordinary electronic, mechanical and structural properties. However, issues of chaotic staking, high cost and high energy dissipation in the synthesis of CNTs remain to be resolved. Here we develop a facile, general and high-yield strategy for the oriented formation of CNTs from metal-organic frameworks (MOFs) through a low-temperature (as low as 430 °C) pyrolysis process. The selected MOF crystals act as a single precursor for both nanocatalysts and carbon sources. The key to the formation of CNTs is obtaining small nanocatalysts with high activity during the pyrolysis process. This method is successfully extended to obtain various oriented CNT-assembled architectures by modulating the corresponding MOFs, which further homogeneously incorporate heteroatoms into the CNTs. Specifically, nitrogen-doped CNT-assembled hollow structures exhibit excellent performances in both energy conversion and storage. On the basis of experimental analyses and density functional theory simulations, these superior performances are attributed to synergistic effects between ideal components and multilevel structures. Additionally, the appropriate graphitic N doping and the confined metal nanoparticles in CNTs both increase the densities of states near the Fermi level and reduce the work function, hence efficiently enhancing its oxygen reduction activity. The viable synthetic strategy and proposed mechanism will stimulate the rapid development of CNTs in frontier fields.

Multidimensional Ordered Bifunctional Air Electrode Enables Flash Reactants Shuttling for High‐Energy Flexible Zn‐Air Batteries

“…As for the lat tice fringes in Figure 2h, they reveal the characteristic lattice spacing of 0.205 nm corresponding to Co (111) plane, which is also in accord with the XRD analysis ( Figure S9, Supporting Information). [18,19,37] These micropores and mesopores in MPZCC@CNT are expected to elongate oxygen molecules trapping periods and enhance its interactions with catalytically active sites. [35] The dif fusion of carbon atoms start around the Co nanoparticles embedded in nanoridges at high temperature, and then the supersaturation of the dissolved carbon atoms induces the for mation of CNTs.…”

Metal‐Organic Framework‐Derived Carbons for Battery Applications

“…Traditionally, PC can be obtained via various methods, such as the direct heat treatment of organic precursors, hard template or nanocast methods, and soft template methods. [22,26,[33][34][35] At present, a large number of studies indicate that zeolitic imidazolate framework-8 (ZIF-8), MOF-5, MIL-125 (Ti) (MIL = Materials of Institute Lavoisier), and ZIF-67 with excellent thermal stability and unique porous structures are the more commonly used MOF precursors (Scheme 1). [23,25,26] Metal-organic frameworks (MOFs) have drawn wide research interest as a novel class of porous materials that are crystalline materials consisting of metal ions and organic ligands.…”

“…However, the production of PC from these methods cannot be scaled-up because of certain barriers (disordered structure with wide size distributions, complicated processes, etc.). [22,26,[33][34][35] At present, a large number of studies indicate that zeolitic imidazolate framework-8 (ZIF-8), MOF-5, MIL-125 (Ti) (MIL = Materials of Institute Lavoisier), and ZIF-67 with excellent thermal stability and unique porous structures are the more commonly used MOF precursors (Scheme 1). [4,21,[27][28][29][30][31] Since the report on the MOF-templated synthesis of PC in 2008, [32] a large number of studies have been reported on the use of MOFs as suitable precursors/templates for carbon synthesis.…”

2D Metal–Organic Framework Derived CuCo Alloy Nanoparticles Encapsulated by Nitrogen‐Doped Carbonaceous Nanoleaves for Efficient Bifunctional Oxygen Electrocatalyst and Zinc–Air Batteries

“…[11,[67][68][69][70][71][72][73] Recently,Z heng and co-workers re-portedC u,Co@NC derivedf rom ZIF-67 and Cu(OH) 2 .I nstead of CuCo alloy nanoparticles,t he Cu and Co nanoparticles were separately but homogeneously distributed in NC framework. [11,[67][68][69][70][71][72][73] Recently,Z heng and co-workers re-portedC u,Co@NC derivedf rom ZIF-67 and Cu(OH) 2 .I nstead of CuCo alloy nanoparticles,t he Cu and Co nanoparticles were separately but homogeneously distributed in NC framework.…”