Controllable Fabrication of Carbon Nanotube and Nanobelt with a Polyoxometalate-Assisted Mild Hydrothermal Process

Abstract

Carbon nanotubes, carbon nanobelts, and carbon nanoparticles can be prepared directly from active carbon powders by a polyoxometalates (POMs)-assisted mild hydrothermal process. After the hydrothermal reaction the POMs are changed into heteropoly blues, which can be converted into the POMs by a small amount of H2O2 solution.

Graphitic Carbon Nanocapsules: Scaled Preparation, Formation Mechanism, and Use as an Excellent Support for Methanol Electro‐oxidation

“…A typical transmission electron microscopy (TEM) image of GCNs derived from PAWBA-[Fe(CN) 6 ] 3-after carbonization at 1100°C and removal of the catalyst is shown in Figure 1. It can be seen that the sample consists of homogeneous hollow capsules with inner diameters of around 15 nm and outer diameters in the range of 30-40 nm (Figure 1a).…”

“…IR spectroscopy provided information on the changes to the organic functional group in the ion-exchange resin during the synthesis. Figure 5 shows the IR spectra of samples derived from the PAWBA-[Fe(CN) 6 ] 3-composite after carbonization at different temperatures. It can clearly be seen that the characteristic peaks of organic groups between 2000 and 3000 cm -1 disappear almost completely as the temperature is raised to 500°C, which indicates that the functional groups in PAWBA had decomposed and that the resin had been completely converted into amorphous carbon.…”

“…Raman spectroscopy also provided evidence for the formation of GCNs. Figure 6 shows the Raman spectra of samples derived from PAWBA-[Fe(CN) 6 ] 3-after carbonization at different temperatures. It is well known that the D band is closely related to the disorder-induced scattering that results from imperfections or the loss of hexagonal symmetry in the structure, whereas the G band arises from the vibration of sp 2 -bonded carbon atoms in a two-dimensional hexagonal lattice.…”

“…[1][2][3] Soon afterwards, the properties of novel carbon nanostructures such as nanocapsules, [4] nanofibers, [5] and nanobelts were also studied. [6] Of these structures it has emerged that graphitic carbon nanocapsules (GCNs) have a wide range of potential applications, for example, in lithium-ion batteries, [7] supercapacitors, [8] hydrogen storage, [9] and drug delivery. [10] Notably, the GCNs have attracted growing research interest for their use as catalyst supports of direct methanol fuel cells (DMFCs) due to their outstanding properties, such as low density, high specific surface area, superb corrosion resistance, excellent electronic transport properties as well as high thermal resistance, high chemical stability, and high rigidity.…”

“…Recently, the solid-state pyrolysis route, which involves the carbonization of carbon precursors containing transition-metal (e.g., Fe, Co, and Ni) graphitization catalysts, has attracted considerable attention for its advantages of easy handling, medium temperatures, and high yields. [15,[19][20][21][22] In previous studies we had developed an effective strategy for the synthesis of highly crystalline GCNs in high yields by a solid-state pyrolysis route using polyacrylic weak-base anion-exchange resin (PAWBA) and K 3 [Fe(CN) 6 ] as the carbon source and catalyst precursor, respectively. [23] Shen and co-workers have subsequently used a similar method for the preparation of graphitic carbon.…”