Tailoring electrical properties of graphene by nitrogen doping is currently of great significance in a broad area of advanced applications. Bonding configuration of nitrogen atoms in graphene plays a vital role in controlling its electrical, chemical, and optical properties. Here, we report for the first time a simple bottom-up synthesis of a novel cationic nitrogen-doped graphene (CNG) by a solution plasma (SP). A mixture of ionic liquid and organic solvent was used as starting precursor. CNG exhibited an orthorhombic structure possibly due to the presence cationic nitrogen in hexagonal graphene lattice. Nitrogen doping content was found to be as high as 13.4 atom %. Electrical characterization demonstrated that the CNG exhibited a p-type semiconducting behavior with superior electrical conductivity and carrier concentration. Such unique electrical characteristics of CNG are mainly attributed to the presence of cationic nitrogen with preserved planar structure.
An excellent corrosion protection for copper nanoparticles by nitrogen-doped few-layer graphene via solution plasma process.
Compared with conventional graphene, few-layer graphene is an easy-to-use material because of its interesting mechanical and chemical properties. Meanwhile, solution plasma (SP) represents a nonequilibrium discharge, which induces electron exchange similar to a catalyst. Thus, SP serves as an electron donor and acceptor between organic molecules and graphite flakes in a solution. Finally, electron exchange leads to the formation of few-layer graphene by peeling graphite flakes. Furthermore, CN-functionalized few-layer graphene (f-FLG) exhibits excellent stability and dispersibility because of the balance of attractive and repulsive forces, i.e., the van der Waals force between the planes and the electrostatic force of the nitrile functional groups on the edges. In this study, f-FLG was successfully synthesized by peeling graphite flakes via electron exchange induced by SP in an aqueous solution containing an ionic liquid (IL) (1-ethyl-3-methylimidazolium dicyanamide (EMIM-DCA)). X-ray diffraction measurements revealed that the intensity of the 002 diffraction of graphite and the crystallite size along the [001] direction decreased to about 5 nm after SP treatment, indicating the progress of graphite flake peeling. Furthermore, the purified product comprised three layers with a crystallite size along the basal plane of about 80 nm evaluated by the deconvolution of the Raman 2D band. X-ray photoelectron spectroscopy confirmed that the synthesized f-FLG contains 7.7 atom % nitrogen, and the IR spectrum revealed the presence of the CN functional group. To understand the peeling mechanism, the ionization potential (I P ) and electron affinity (E A ) of the IL in water, and the averaged electron excitation temperature (T e ) in plasma were estimated by ab initio molecular orbital calculations, cyclic voltammetry, and optical emission spectroscopy. An energy diagram of I P , E A , and T e shows that SP served to pump electrons for their circulation via EMIM-DCA and to remove electrons from graphite flakes and inject into f-FLG.
The exploration of novel carbon material systems has emerged as a promising strategy for yielding unique and unconventional functional properties. In this study, a cationic nitrogen-doped carbonwrapped single-walled carbon nanotube (CN−C@SWCNT) was synthesized for the first time via solution plasma (SP) by using an aniline aqueous solution with the SWCNT dispersion under ambient conditions. The reactive species produced from SP led to the formation of cationic nitrogendoped carbon (CN−C) completely wrapped around SWCNT. Raman spectroscopy, electron diffraction, and X-ray photoelectron spectroscopy confirmed the presence of cationic nitrogen. CN−C@SWCNT exhibited an excellent electrical conductivity of 120.30 S cm −1 . Room-temperature halleffect measurements revealed p-type semiconducting behavior for CN−C@ SWCNT, with a carrier concentration of 4.6 × 10 20 cm −3 . The electrical conductivity and carrier concentration of p-type CN−C@SWCNT were greater than those reported previously for carbon-based materials. The high electrical properties of CN−C@SWCNT were synergistically related to a conducting bridge between CN−C and SWCNT conducting domains and the presence of doped cationic nitrogen. The SP-synthesized CN−C@SWCNT demonstrates immense potential as an emerging class of p-type carbon materials in advanced electrocatalytic applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.