Unique Single‐Crystalline Beta Carbon Nitride Nanorods

Abstract

The discovery of the carbon nanotube has opened a challenging new field in materials, solid-state physics, and chemistry, offering a wide perspective for many possible applications.[1] The successful synthesis of functional ceramic micro-or nanostructures such as BN, [2,3] WS 2 , [4] MoS 2 , [5] In 2 O 3 , [6] TiO 2 , [7] and so forth has been reported. The theoretical prediction of a super-hard carbon nitride solid of composition C 3 N 4 (space group P6 3 /m) by Liu and Cohen [8] has directed the efforts of many experimental groups to synthesize this compound.[9±14] It has been extensively claimed that the carbon nitride compound could be formed in thin amorphous films by several methods such as shock-wave compression technology, pyrolysis of high nitrogen content precursors, diode sputtering, solvothermal preparation, pulsed laser ablation, and ion implantation. The hypothetical b-C 3 N 4 has the same crystal structure as b-Si 3 N 4 , with a hexagonal network of tetrahedrally (sp 3 ) bonded carbon and trigonal planar nitrogen (sp 2 ). Besides its predicted hardness, carbon nitride is also considered to be very promising in the fields of tribological and wear-resistance coating and optical and electronic engineering. [15±19] Although extensive studies on the synthesis and the characterization of carbon nitride materials have been reported, so far the nitrogen concentration of the formed carbon nitrogen compound is usually below the ideal composition for C 3 N 4 . Furthermore, the bonding between C and N tends to be of sp 2 -type character. An appropriate synthetic route to obtain the C 3 N 4 solid is still unknown. The difficulties in the synthesis of hard carbon nitrides are very likely related to their low thermodynamic stability with respect to the elements (C and N), indicated by a positive value of the enthalpies of formation. [20] Therefore, it will be particularly important to find effective and low-cost methods for synthesizing carbon nitride single crystals with a chemical composition of 3:4 for C/N. With this aim in view, we have recently succeeded for the first time in synthesizing single crystal b-C 3 N 4 nanorods in gram quantities via a simple route. As is known, the mechanochemical reaction may offer a possible method for materials synthesis under non-equilibrium condition with several advantages over conventional methods such as the production of non-aggregate and uniform particles in the nanometer scale range. [21,22] It may be used to drive a wide range of chemical reactions and can be performed under a controlled atmosphere to initiate solid±solid and solid±gas reactions to obtain special phases that could only be synthesized under extreme conditions such as high pressure and high temperature (HPHT), thus providing a low-cost method for synthesizing carbon nitride crystal. In this communication, nanostructured porous amorphous carbon powders with a high surface area and structural defects were firstly obtained by a high-energy mechanical process, then they were continually high-en...

One-dimensional nanomaterials synthesized using high-energy ball milling and annealing process

“…Without ball milling, SiOC nanowires are obtained at 1200 1C possibly because of the lack of sufficient activation energy. Some chemical reactions could take place even during the room temperature ball-milling process [43,49]. For example, nitriding reactions between B powder and NH 3 gas occurred during the ball-milling process with the formation of nanosized BN structures, which serve as nucleation structure for BN nanotube growth during the annealing [5].…”

“…This mechanism is supported by other experimental observations. Yin et al [43] first ball mill graphite in NH 3 up to ARTICLE IN PRESS 120 h, in which a nitriding reaction between graphite and NH 3 gas occurs with the formation of amorphous CN phase. The milled sample is annealed in the temperature range of 300-450 1C under a flow of NH 3 gas to produce b-CN nanorods.…”

Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

“…Several methods have been used to prepare nitrogen-doped CNTs with various amounts of doping (Guo et al 2004;Kouvetakis et al 1994;Oku and Kawaguchi 2000;Yin et al 2003) such as pyrolysis of nitrogen-containing materials with CNTs (Golberg et al 2000), D.C. Magnetron sputtering (Suenaga et al 1999), CVD (Liu et al 2010), aerosol method (Glerup et al 2003), etc. Among these methods, PECVD is one of the most effective approaches for doping the CNTs.…”

Large scale production of novel g-C3N4 micro strings with high surface area and versatile photodegradation ability

“…Moreover, the string-like morphology also had advantages over nanowires and nanotubes in lithiation and de-lithiation processes in lithium ion batteries. 33 Thus, an easy and scalable method is required to prepare g-C 3 N 4 with high surface area and specific morphology without using templates and toxic chemicals to make its application more practical in the fields of catalysis and energy storage.…”