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Atomic Transport at Charged Graphene: Why Hydrogen and Oxygen Are So Different
Author(s) -
Nguyen ManhThuong,
Phong Pham Nam
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201700484
Subject(s) - graphene , doping , diffusion , materials science , hydrogen , density functional theory , electron , adsorption , electron mobility , electrochemistry , chemical physics , nanotechnology , chemistry , computational chemistry , electrode , physics , optoelectronics , thermodynamics , organic chemistry , quantum mechanics
Atoms on charged graphitic carbon surface are relevant to various electrochemical problems, understanding the adsorption and diffusion of adatoms under charging conditions is essential towards using graphene‐like materials in electrochemistry. Using density functional calculations, we show that electron or hole doped graphene can strongly change the mobility of H and O adsorbed atoms. Interestingly, charge doping affects the diffusion of H and O in opposite ways, namely, electron doping increases/reduces, while hole doping reduces/increases the diffusion barrier of H/O respectively. Specifically, on neutral graphene the diffusion barriers of H and O are 1.01 and 0.74 eV, which are, upon a hole doping level of +5.9 × 10 13 cm −2 , 0.77 and 0.90 eV, and upon an electron doping level of −5.9 × 10 13 cm −2 , 1.36 and 0.38 eV. Thus, within the harmonic transition state theory, at room temperature, the diffusion rate of O can be decreased or increased by 470 or 1 × 10 6 times, while that of H can be increased or decreased by 1 × 10 4 or 7 × 10 5 times, respectively for the above hole or electron doping density. The difference between H and O atomic transport at charged graphene is interpreted in terms of the difference in geometric and bonding changes upon charge doping.