Charge carrier exchange at chemically modified graphene edges: a density functional theory study

Abstract

Heteroatom doping on the edge of graphene may serve as an effective way to tune chemical activity of carbon-based electrodes with respect to charge carrier transfer in an aqueous environment. In a step towards developing mechanistic understanding of this phenomenon, we explore herein mechanisms of proton transfer from aqueous solution to pristine and doped graphene edges utilizing density functional theory. Atomic B-, N-, and O-doped edges as well as the native graphene are examined, displaying varying proton affinities and effective interaction ranges with the H 3 O + charge carrier. Our study shows that the doped edges characterized by more dispersive orbitals, namely boron and nitrogen, demonstrate more energetically favourable charge carrier exchange compared with oxygen, which features more localized orbitals. Extended calculations are carried out to examine proton transfer from the hydronium ion in the presence of explicit water, with results indicating that the basic mechanistic features of the simpler model are unchanged.

Nanoarchitectured Graphene‐Based Supercapacitors for Next‐Generation Energy‐Storage Applications

“…49 The influence of boron on the double‐layer capacitance was further explored by a density functional theory (DFT) study on the zigzag edges of doped graphene nanoribbons (ZGNR) to reveal the ability of charge carriers to absorb onto the B‐doped carbons. The results showed that the larger critical distance for proton binding is obtained in comparison with N‐ and O‐doped edges,50 indicating easier proton binding on B‐doped ZGNR, which correlates well with the higher interfacial capacitance for B‐doped carbons reported in previous literature 36. 41 In addition, the maximum proton binding onto the substituted ZGNR was demonstrated to follow the rule of [8‐ n ‐1], where n represents the number of valence electrons of the substituted atom on the adsorption edge site 51.…”

“…Similar to B doping, the incorporation of nitrogen changes the surface electronic property of graphene and enhances the double‐layer capacitance of the doped carbons. The DFT (density functional theory) study for the proton adsorption on the doped edges indicates that proton exhibits stronger interactions with N‐doped edges rather than B‐ or O‐doped edges,50 which may be ascribed to the increased basicity introduced by N‐containing functional groups on the surface 46. 64 Different from the case for O‐containing functional groups, which bear more acidic groups (e.g., carboxylic groups and lactones)65 than basic and neutral groups (e.g., phenols, ethers, and carbonyls) to render acidic surface nature on carbons, the presence of N‐containing functional groups introduces more basicity, especially for the ones containing high amounts of N‐6 and N‐5 due to their electron donor characteristics 37a.…”

The role of the defect on the adsorption and dissociation of water on graphitic carbon nitride

“…The diffusion of hydroxyl in water is by the way of formation the transitional structure with its neighbor water molecule. It is reported that N loaded graphene nanoribbon edges shows active proton affinity [58,59]. The structure of the defect site within g-C 3 N 4 sheet is similar to the N loaded graphene nanoribbon edges.…”

Origin of multiple band gap values in single width nanoribbons

“…Since 2007, hundreds of theoretical papers have been published on GNRs focused only on how to explain non-zero band gap in both the crystallographic orientations of GNRs based on different edge passivating patterns with different type of edge passivating elements. [21][22][23][24][25][26][27][28] , the multiple band gap values in the same width of nanoribbons remains unresolved. Therefore, in this work, we for the first time propose a resolution for the physical origin of multiple band gap values in single width nanoribbons, which would resolve the critical concern over the scalable production of pristine and/or hetero-structure nanoribbons with deterministic properties for plethora of applications.…”