Modulation of the thermodynamic, kinetic, and magnetic properties of the hydrogen monomer on graphene by charge doping

Abstract

The thermodynamic, kinetic and magnetic properties of the hydrogen monomer on doped graphene layers were studied by ab initio simulations. Electron doping was found to heighten the diffusion potential barrier, while hole doping lowers it. However, both kinds of dopings heighten the desorption potential barrier.The underlying mechanism was revealed by investigating the effect of doping on the bond strength of graphene and on the electron transfer and the coulomb interaction between the hydrogen monomer and graphene. The kinetic properties of H and D monomers on doped graphene layers during both the annealing process (annealing time t 0 =300 s) and the constant-rate heating process (heating rate α =1.0 K/s) were simulated. Both electron and hole dopings were found to generally increase the desorption temperatures of hydrogen monomers. Electron doping was found to prevent the diffusion of hydrogen monomers, while the hole doping enhances their diffusion. Macroscopic diffusion of hydrogen monomers on graphene can be achieved when the doping-hole density reaches 5.0 × 10 13 cm −2 . The magnetic moment and exchange splitting were found to be reduced by both electron and hole dopings, which was explained by a simple exchange model. The study in this report can further enhance the understanding of the interaction between hydrogen and graphene and is expected to be helpful in the design of hydrogenated-graphene-based devices.

Theoretical study of the dynamics of atomic hydrogen adsorbed on graphene multilayers

“…The electronic state thus induced will correspond to that of a nonmagnetic insulator for large concentrations [1][2][3][4][5], an antiferromagnet for intermediate concentrations [19], or a paramagnet for low concentrations [12]. At room temperature, which for practical applications is the most interesting case, both desorption and diffusion processes are, in principle, active [20][21][22][23][24][25][26][27][28][29][30]. If desorption rates are larger than diffusion ones, the sample will loose H from both sublattices, but at different rates.…”

“…This result does not qualitatively depend on the specific values of the migration and desorption barriers. For instance, upon changing the carrier concentration of the bilayer system, which, in turn, changes the magnitude of these barriers [29], we always obtain such temporary distribution of H, only the final fate of the atoms being affected. For hole doping, all atoms eventually form dimers or clusters while for electron doping (or no doping) all atoms eventually desorb.…”

Strain Effects in Gallium Nitride Adsorption on Defective and Doped Graphene: First-Principles Calculations

“…As shown in Figure 3a, the largest adsorption energy of the gallium adatom on Ga-doped graphene surface is −0.509 eV, which is only 0.16 eV (absolute value) larger than that on pristine graphene. These results can be explained by the fact that, after replacing the carbon atom, the gallium atom becomes an acceptor and thus easily interacts with the metal gallium [34,35]. As can be seen from Figure 3b, all the adsorption energies of the gallium adatom are reduced when they are adsorbed on N-doped graphene.…”

“…The results indicate that the incorporation of oxygen impurities makes it harder for the gallium atom to be adsorbed on the graphene, and even physical adsorption becomes very difficult. the gallium atom becomes an acceptor and thus easily interacts with the metal gallium [34,35]. As can be seen from Figure 3b, all the adsorption energies of the gallium adatom are reduced when they are adsorbed on N-doped graphene.…”

Selective Hydrogen Adsorption in Graphene Rotated Bilayers

“…32 At this point it is interesting to study the effect of doping on the chemisorption energy. 40 By adding electrons or holes the Fermi energy would move from the Dirac points where the density of states is zero, to energies where the density of states is larger and, eventually, at the van Hove logarithmic singularities, where the density of states is much larger. In Figure 6 we show the calculated density of states at the Fermi as a function of the extra charge.…”