Edge Chemistry of Armchair Graphene Nanoribbons Containing Sulfur Functional Groups: Towards an Understanding of the Spin‐Dependent Electrochemistry

Abstract

Numerous sulfur functional groups (35) attached to the edges of armchair graphene nanoribbons are investigated through the use of quantum mechanical calculations. Results for the band structure, formation energy, charge transfer, total hydrophilicity index, and electronic bandgaps are shown. The thiophene‐like functional group proved to be the most energetically stable, followed by the pyrrolic‐N‐sulfide. Typically, the sulfurized functional groups pulled out electrons from the ribbon, promoting p‐type doping. Ferromagnetic semiconducting behavior is found in thioketone, pyrrolic‐N‐sulfide, thiopyran‐like dioxide, and N‐thionyl aniline functional groups. Results for the valence band maximum and conduction band minimum energies demonstrate that thiopyran‐like dioxide is energetically favorable to remove spin‐down electrons, whereas thioketone is energetically favorable to catch spin‐down electrons. This fact gives insight into future spin‐dependent electrochemistry studies on functionalized graphite materials. Results for lithium adsorption demonstrate that the donated charge by lithium and interatomic distance between Li and the functional groups are strongly dependent on the nature of the functional group.

Nitrogen and Sulfur Incorporation into Graphene Oxide by Mechanical Process

“…Finally, G-T-BM samples exhibited electrocatalytic processes related to sulfur functionalization groups with N, O at the graphitic edges. [33][34][35] Based on previous reports, the G-T-BM electrocatalytic processes (blue line in Figure 11d) could be related to pyrrolic-N-sulfide, sulfhydryl oxidation (thiol) to thiolate reduction (thioketone), thiophene-like dioxide, and other oxidized sulfur ─SO functional groups. [36][37][38][39][40][41] To elucidate the role of urea and thiourea in the electronic properties of sp 2 carbon materials, we performed first-principles density functional theory (DFT) calculations on C 96 H 24 graphene sheets with zigzag edges.…”

“…Finally, G‐T‐BM samples exhibited electrocatalytic processes related to sulfur functionalization groups with N, O at the graphitic edges. [ 33–35 ] Based on previous reports, the G‐T‐BM electrocatalytic processes (blue line in Figure 11d) could be related to pyrrolic‐N‐sulfide, sulfhydryl oxidation (thiol) to thiolate reduction (thioketone), thiophene‐like dioxide, and other oxidized sulfur SO functional groups. [ 36–41 ]…”

Nitrogen–phosphorus doped graphitic nano onion-like structures: experimental and theoretical studies

“…They reported GNOs with diameters ranging from 200 to 600 nm. Graphitic materials have been doped with nitrogen, 18 boron, 19 sulfur, 20,21 beryllium, 22 and phosphorus. 23,24 The doping in graphitic materials can improve their electrochemical activity taking advantage of the different electronegativity of the dopants, which can polarize the adjacent atoms.…”