Diffusion Monte Carlo study of O2 adsorption on single layer graphene

Abstract

Diffusion Monte Carlo (DMC) calculations were performed for an accurate description of the nature of the O 2 adsorption on a single layer graphene. We investigated the stable orientation of O 2 at a specific adsorption site as well as its equilibrium adsorption energy. At equilibrium adsorption distances, an O 2 molecule was found to prefer a horizontal orientation, where the O-O bond is parallel to the graphene surface, to the vertical orientation. However, the vertical orientation is favored at the O 2 -graphene distances shorter than the equilibrium distance, which could be understood by the steric repulsion between O and C atoms. Contrary to previous DFT calculations, our DMC calculations show that the midpoint of a C-C bond (a bridge site) is energetically preferred for the O 2 adsorption to a center of a hexagonal ring (a hollow site). The lowest DMC adsorption energy was found at an intermediate point between a hollow and a bridge site, where the O 2 adsorption energy was estimated to be −0.142(4) eV that was in very good agreement with the recently-reported experimental value. Finally, we have found that O 2 is very diffusive on the surface of graphene with the diffusion barrier along a bridge-hollow-bridge path being as small as ∼ 11 meV.

The binding of atomic hydrogen on graphene from density functional theory and diffusion Monte Carlo calculations

“…56 The DMC calculations were performed using the branching scheme proposed by Zen et al (ZSGMA) 57 with a population control target of 8,192 walkers and a time step of 0.005 a.u., which represented a balance between computational cost and finite timestep error in previous work. 58 We define the binding energy as,…”

“…To bring these applications to fruition, a deeper understanding of the interaction of atoms and molecules with graphene is required, and, not surprisingly, this has been the subject of several experimental and theoretical studies. [1][2][3][4][5][6][7][8][9][10][11][12][13] The adsorption of H atoms on graphene has been the subject of multiple studies. 3,[10][11][12][13][14] It is known that there is both a weakly absorbed state in which barriers for diffusion are small and a much more strongly bound chemisorbed state.…”

“…DMC also has the advantages of being systematically improvable and being much less sensitive to the basis set employed than methods that work in the space of Slater determinants. DMC has been used to describe the adsorption of various species on graphene including O 2 4 , a water molecule 5,29 , and a platinum atom. 6 In a study of a physisorbed H atom on graphene, Ma et al found that different DFT functionals gave binding energies ranging from 5 to 97 meV, while DMC calculations gave a value of only 5 ± 5 meV.…”

Adsorption of singlet and triplet oxygen on B-doped graphene: adsorption and electronic characteristics

“…30,33 It is also suggested that Si-doped surfaces can be a metal-free catalyst for oxygen reduction reactions (ORRs). 33 Diffusion Monte Carlo (DMC) calculations were also performed for O 2 adsorption on single-layer graphene 31 to describe the adsorption's nature accurately. They have obtained adsorption energy of −0.142 eV, close to the experimental value of −0.15 eV.…”

“…Using the computational rstprinciples technique, Nakamura et al 26 found that oxygen atoms selectively adsorb on intrinsic graphene, forming epoxide rings and modifying structural and electrical characteristics. There have been a few experimental 5,[27][28][29] and theoretical attempts 13,16,[30][31][32][33][34][35][36][37] to explore the sensing of molecular dioxygen, O 2 , on pristine and doped graphene monolayers. Some earlier literature reveals attempts to make oxygen sensors 27,28 with monolayer graphene.…”