Nitrogen-Doping Chemical Behavior of Graphene Materials with Assistance of Defluorination

Abstract

Heteroatom-doping reactions are essential to achieve advanced graphene-based materials for energy and biological areas. Unfortunately, considerably less is known regarding the detailed reaction pathways up to now. Here, we focus on investigating the nitrogen (N) doping process of fluorinated graphene (FG) under the assistance of defluorination based on modified in situ Fourier transform infrared spectroscopy. It was demonstrated FG possesses a higher and more effective reactivity with ammonia in comparison with other graphene derivatives, which enable N-doping to proceed efficiently with assistance of defluorination even at a lower temperature (16.8 at. % of N at 300 °C and 19.9 at. % of N at 400 °C). Combining with Density functional theory, it was proved that, at the initial reaction step of N-doping, ammonia molecule attacked and substituted the C–F of FG by the new C-NH2. Sequentially, amino group was cyclized to the three-membered ring of ethylenimine. More importantly, the dissociation and migration of C–F bonds facilitates the dissociating of C–C bonds and the recombining of C–N bonds, thus significantly promoting the N atom in ethylenimine ring to transform to the pyridinic-N or graphitic-N in graphene skeleton.

Tunable Synthesis of Nitrogen Doped Graphene from Fluorographene under Mild Conditions

“…However, although a structurally well-defined graphene derivative was used as a substrate, allowing homogeneous doping, the pathway relied on established high temperature routes and yielded only low N content. It was also demonstrated that FG can undergo direct N-doping by ammonia gas which occurs simultaneously with defluorination at temperatures between 200 and 400 °C. , Density functional theory (DFT) calculations have revealed that the first reaction step involves nucleophilic substitution of fluorine atoms by amino groups, which can then undergo deprotonation and cyclization into aziridinic configurations. These could potentially be transformed into either pyridinic or graphitic N in the honeycomb carbon lattice.…”

Recent Advances in Fluorinated Graphene from Synthesis to Applications: Critical Review on Functional Chemistry and Structure Engineering

“…In addition to the aforementioned application fields, the application of FG in other aspects have also been preliminarily reported by investigators. [170,[218][219][220][221][222][223][224][225][226][227][228][229][230] Zhao et al's study indicated that FG with single-sided fluorination could be used as the metal-free electrocatalyst in ORR reactions. Through simulations, single-sided fluorinated graphene had a high spin density, which enhanced the adsorption of O 2 and promoted the 4e − reaction process with an excellent electrocatalytic activity.…”

“…In addition to the aforementioned application fields, the application of FG in other aspects have also been preliminarily reported by investigators. [ 170,218–230 ] Zhao et al. 's study indicated that FG with single‐sided fluorination could be used as the metal‐free electrocatalyst in ORR reactions.…”

Environmental Remediation Applications of Carbon Nanotubes and Graphene Oxide: Adsorption and Catalysis

“…CNTs are indeed a new class of material useful for environmental applications because of their cylindrical hollow structure, large surface area, high length to radius ratio, and hydrophobic wall and surface that can be easily modified [13].GO is one oxidized analog of graphene, recognized as the promising intermediate for obtaining the latter in large scale [14], since Brodie centuries ago first reported about the oxidation of graphite [15]. Three decades earlier, one atom-thin single layer of graphite was officially defined with the term graphene [16], structurally comprising sp 2 hybridized carbon atoms arranged in a honeycomb lattice, characterized by promising properties in terms of mechanical, electrical, and other [17][18][19]. Despite well-known properties, GO remains limited success in practical applications, mainly due to the difficulties in large-scale production of desired highlyorganized structure [20].…”