Polymerized carbon nitride nanobells

Abstract

Well-aligned carbon nitride nanotubes are fabricated by microwave plasma assisted chemical vapor deposition using iron as the catalyst. These nanotubes are linearly polymerized by carbon nitride nanobells with catalyst particles in the root, as revealed by high-resolution transmission electron microscopy. Carbon nitride nanotube film is analyzed by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Raman spectroscopy. Both XPS and AES reveal a nitrogen content of about 2% in the film. Raman spectroscopy exhibits a good crystallization of these carbon nitride nanotubes. Electron energy loss spectroscopy is used to study the local distribution of nitrogen in a single nanotube, which indicates that nitrogen prefers to locate at curved graphite sheets, at the top of the nanobells, and that incorporation of nitrogen results in the decrease of the crystallization. Based on these results, a growth model is proposed to explain this periodically stacked nanobell structure. In this model, we propose that graphite sheets only precipitate along the surface of catalyst particles and that lower growth rate at the top curve surface of the bell-like catalyst particle is the key factor influencing formation of this special microstructure. A heterojunction between a tubular carbon nanotube and a carbon nitride nanobell also has been fabricated by a two-step growth technique. And short carbon nitride nanotubes with a few nanobells or even just one nanobell are obtained by both physical and chemical methods. Furthermore, we studied the field emission properties and have obtained a threshold field of as low as about 1 V/μm. A novel side-emission mechanism has been proposed based on the special polymerized nanobell structures.

Nitrogen Doping Effects on Carbon Nanotubes and the Origin of the Enhanced Electrocatalytic Activity of Supported Pt for Proton-Exchange Membrane Fuel Cells

“…36 Pyridinic nitrogen is bonded to two carbon atoms and donates one p electron to the aromatic π system (C-NdC). [37][38][39] Nitrogen-doping in the pyridinic sites is believed to be responsible for both the wall roughness and the interlinked morphologies. 40 This is in good agreement with the TEM observations above.…”

“…Graphitic nitrogen is a nitrogen atom, which replaces a carbon atom within a graphite plane and is bonded to three carbon atoms ( ). [37][38][39] Oxidized nitrogen is oxidized pyridinic nitrogen, which is bonded to two carbon atoms and one oxygen atom ( ). [41][42][43][44] Molecular N 2 are nitrogen molecules adsorbed/intercalated at the carbon walls or trapped in the compartments, which has been confirmed by the X-ray absorption near-edge structure analysis 45 and scanning transmission X-ray microscopy.…”

Comparative study of BxNyCz nanojunctions fragments

“…Our previous works showed that incorporation of nitrogen zigzag nanotubes stabilizes some geometries 22,23 . In the case of carbon atoms substitution by boron and nitrogen atoms, our theoretical results showed that BN-pair substitution depends on the tube diameter.…”

“…Some studies have shown that heteroatoms (as boron and nitrogen) are met in defective regions of tubes 21 . In the case of nitrogen doping nanotubes, there are two results due the inclusion of this heteroatom: (i) the lone pair repulsion decreases the bond angle between nitrogen and carbon atoms which brings on structural stabilization; (ii) one pentagon with nitrogen simulates a carbon hexagon due the extra electron in the nitrogen atom which stabilizes the electronic structure of joint region [22][23] . Emission mechanisms, conduction, and rectification processes are not understood if they are measure from carbon nanostructures.…”

Conformational analysis and electronic structure of chiral carbon and carbon nitride nanotubes

“…Nitrogendoped carbon nanotubes render them n-type material regardless of tube chirality 39 , and nitrogen in doped carbon nanotubes acts as a donor. In particular, nitrogen-doped carbon nanotubes are effective field emitters [40][41][42][43] . CNx nanotubes have been demonstrated to show lower turn-on and higher current density than undoped carbon nanotubes 42 .…”