Evolution of the Composition and Suspension Performance of Nitrogen-Doped Graphene

Abstract

Nitrogen functionalization of graphene enables it to be used for catalysis and targeted adsorption of biomolecules in both the solid state and in suspension. Thus, we sought to characterize the functional groups and suspension charge behavior of nitrogen-doped graphene (NDG) prepared in the absence of hydrazine, a highly toxic reagent. The hydrothermal reaction of graphite oxide (GO) with ammonia was shown to effectively remove oxygen and to restore the graphitic framework within the resulting NDG sheets. The enhanced graphitic character of the NDG materials was verified using X-ray photoelectron spectroscopy, thermogravimetic analysis, and electrical conductivity measurements. With six hours of reaction time (sample NDG-6), up to 9.6 wt % (7.1 atomic %) of nitrogen could be introduced into the graphene. All the NDG materials exhibited excellent dispersibility in water allowing their surface charge to be probed by measuring zeta potential (ζ) as a function of suspension pH. The NDG-6 material could hold surface charge ranging from ζ = −50 mV to ζ = +20 mV, which is, to the best of our knowledge, the widest range of surface charges measured on a colloidal graphene material.

Photoluminescence from amino functionalized graphene quantum dots prepared by electrochemical exfoliation method in the presence of ammonium ions

“…Recently, the chemical doping of GNs with heteroatoms like sulfur, boron and nitrogen has emerged due to its ability to provide fascinating optical and electronic characteristics. [8][9][10] Both dopant type and concentration have been considered as crucial factors to alter the band structure of graphene, i.e., the energy gap between valence and conduction bands. 10 Particularly, nitrogen-doping in carbon delivers a very promising potential in a variety of applications such as graphene quantum dots (GQDs).…”

N-doped carbon layer coated thermally exfoliated graphene and its capacitive behavior in redox active electrolyte

“…Nevertheless, heteroatom doping (nitrogen, boron [16], or sulfur [17]) on a carbon framework exhibits effective improvement by resolving the problems such as ameliorating rinse and increasing reactivity of carbon electrodes. Nitrogen doping can be achieved either through post-treatment with small molecular agents such as, urea [18] and ammonia gas [19] or via carbonization of nitrogen-rich polymer precursors, like polyacrylonitrile [20], methylated melamine resin [21], and polypyrroles [22]. Comparatively, the methods using post-treatment often resulted in the detachment of unstable functional groups, which seriously reduces the capacitive performance after multiple charge-discharge cycles.…”

Preparation, characterization, and physical properties of graphene nanosheets and films obtained from low-temperature expandable graphite

“…The absence of significant weight loss below 300°C reveals that the graphene powders did not incorporate large amounts of oxygen-containing functional groups [47]. The broad exothermic peak at 337°C may be related to the thermal decomposition of intercalating agents [48].…”