Semiconducting single-walled carbon nanotubes synthesized by S-doping

Abstract

An approach was presented for synthesis of semiconducting single-walled carbon nanotubes (SWNTs) by sulfur (S) doping with the method of graphite arc discharge. Raman spectroscopy, UV-vis-NIR absorption spectroscopy and electronic properties measurements indicated the semconducting properties of the SWNTs samples. Simulant calculation indicated that S doping could induce convertion of metallic SWNTs into semiconducting ones. This strategy may pave a way for the direct synthesis of pure semiconducting SWNTs. Depending on their diameter and chirality, SWNTs can exhibit either metallic or semiconducting behavior. However, the chirality of nanotubes can not be controlled normally until now S-doped SWNTs were synthesized by arc discharge between two graphite electrodes in hydrogen atmosphere. The graphite electrodes were graphite rods of ~6 mm in diameter and made with high purity graphite, iron (5 at%) and S (0.1-2.0 at%).Briefly, the synthesis apparatus consists of graphite electrodes, a water-cooled trapወ and a DC power supply which is capable of providing the voltage of 150 V and the current of 100 A.During DC arc discharge process, the distance between the graphite electrodes was maintained about 2 mm. The optimum

Experimental evidence for the formation mechanism of metallic catalyst-free carbon nanotubes

“…Recently, we have obtained CNTs in the absence of metallic catalysts with chemical vapor depostion (CVD). This work not only shows our former suggestion [7], but also can obtain the so-called pure CNTs which show really properties of CNTs [15].…”

The synthesis of carbon nanomaterials using chlorinated hydrocarbons over a Fe-Co/CaCO3 catalyst

“…Modification of CNTs has thus led to the creation of new functional and construction materials. 11 Doping of the carbonaceous materials with non-carbon atoms, such as nitrogen, [12][13][14][15][16][17][18][19] boron, [20][21][22][23][24] sulphur, [25][26][27][28][29] oxygen [30][31][32][33][34][35][36] and halogens 11,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] has been explored over the past two decades. Modification of the carbon surface and electronic properties has also been explored but the effect of chlorine (Cl) on the morphology of carbon nanomaterials is not well established.…”

Covalent bromination of multi-walled carbon nanotubes by iodine bromide and cold plasma treatments

“…can be tailored by the covalent or not covalent functionalization with several heteroatoms or molecules [1][2][3][4][5][6]. Thus, the covalent bonding of oxygen to CNTs has been widely reported and these of nitrogen, sulfur and phosphorous have also been explored [7][8][9][10][11][12][13][14]. Also it has been reported the functionalization of carbon nanotubes with different halogens [15][16][17].…”