Ab initio model study on a water molecule between graphite layers

Ruuska, Henna; Pakkanen, Tapani A.

doi:10.1016/s0008-6223(02)00381-0

Cited by 32 publications

(19 citation statements)

References 24 publications

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“…The origin of the tribological phenomena derives from the interactions between atoms that belong to the surfaces, an understanding of which requires atomic-scale investigations. Previous molecular dynamics [25][26][27][28][29][30][31][32][33][34][35][36][37][38] and ab initio studies [39][40][41][42][43][44][45][46] have provided useful information about friction, providing friction coefficients in agreement with experimental observations. For h-BN, ab initio calculations give a friction coefficient of 0.226-0.265 [45], the experimental value being 0.23-0.25 [20].…”

Section: Introductionmentioning

confidence: 64%

Friction and a Tribochemical Reaction between Ice and Hexagonal Boron Nitride: A Theoretical Study

2008

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Friction between ice-Ih and hexagonal boron nitride (h-BN) has been determined by periodic ab initio calculations. Surfaces of ice-Ih and h-BN were brought into sliding contact, and the interaction energies were calculated as a function of interplanar distance and lateral displacement of the surfaces. The friction between the surfaces was calculated from the interaction energies, producing a friction coefficient of 0.140. Friction is further influenced at high loads by a tribochemical reaction between ice-Ih and h-BN.

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Section: Introductionmentioning

confidence: 64%

Friction and a Tribochemical Reaction between Ice and Hexagonal Boron Nitride: A Theoretical Study

2008

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“…On a smaller scale, an ultramicoporous matrix of mostly closed pores essentially consists of interconnected small polyaromatic clusters where heteroatoms are predominantly located along edges. Although individual water molecules measure only ~0.28 nm in diameter and can be adsorbed between graphite layers (e.g., Ruuska and Pakkanen, 2003), water does not easily penetrate the interlayer spacing of crystalline carbon structures into <0.4 nm diameter ultramicropores in high-rank coal, possibly due to individual water molecules' inability to maintain liquidity (Prinz and Littke, 2005). At the same time, the mobility of water within the carbonaceous ultramicoporous matrix is reduced by increasing surface hydrophobicity resulting from heteroatom removal and aromatization, although hydration of the exterior carbon surface of carbonaceous grains is facilitated by oxidation (e.g., Lerf et al, 2006), and the reduced polarity and viscosity of water at elevated temperatures facilitate the access of water to the carbonaceous matrix (Molina-Sabio et al, 2006).…”

Section: Proposed Model Of Progressive Metamorphism Of Organic Nitrogenmentioning

confidence: 99%

Organic nitrogen chemistry during low-grade metamorphism

Boudou

Schimmelmann

Ader

et al. 2008

Geochimica et Cosmochimica Acta

136

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-Most of the organic nitrogen (N org ) on Earth is disseminated in crustal sediments and rocks in the form of fossil nitrogen-containing organic matter. The chemical speciation of fossil N org within the overall molecular structure of organic matter changes with time and heating during burial. Progressive thermal evolution of organic matter involves phases of enhanced elimination of N org and ultimately produces graphite containing only traces of nitrogen. Long-term chemical and thermal instability makes the chemical speciation of N org a valuable tracer to constrain the history of sub-surface metamorphism and to shed light on the subsurface biogeochemical nitrogen cycle and its participating organic and inorganic nitrogen pools. This study documents the evolutionary path of N org speciation, transformation and elimination before and during metamorphism and advocates the use of XRay Photoelectron Spectroscopy (XPS) to monitor changes in N org speciation as a diagnostic tool for organic metamorphism. Our multidisciplinary evidence from XPS, stable isotopes, traditional quantitative coal analyses, and other analytical approaches shows that at the metamorphic onset N org is dominantly present as pyrrolic and pyridinic nitrogen. The relative abundance of nitrogen substituting for carbon in condensed, partially aromatic systems (where N is covalently bonded to three C atoms) increases exponentially with increasing metamorphic grade, at the expense of pyridinic and pyrrolic nitrogen. At the same time, much N org is eliminated without significant nitrogen isotope fractionation. The apparent absence of Rayleigh-type nitrogen isotopic fractionation suggests that direct thermal loss of nitrogen from an organic matrix does not serve as a major pathway for N org elimination. Instead, we propose that hot H, O-containing fluids or some of their components gradually penetrate into the carbonaceous matrix and eliminate N org along a progressing reaction front, without causing nitrogen isotope fractionation in the residual N org in the unreacted core of the carbonaceous matrix. Before the reaction front can reach the core, an increasing part of core N org chemically stabilizes in the form of nitrogen atoms substituting for carbon in condensed, partially aromatic systems forming graphite-like structural domains with delocalized π-electron systems (nitrogen atoms substituting for "graphitic" carbon in natural metamorphic organic matter). Thus, this nitrogen species with a conservative isotopic composition is the dominant form of residual nitrogen at higher metamorphic grade.

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“…With this in mind, water on graphite or graphene has been used as a model system with which to benchmark the water-carbon bond strength. [5][6][7][8][9][10][11][12] Traditionally, fused benzene rings (a finite cluster model) have been adopted, enabling the application of explicitly correlated quantum chemistry approaches. Adsorption energies from these approaches range from −100 meV to more than −200 meV, 5,7,9 with recent values being about −130 to −140 meV.…”

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confidence: 99%

Adsorption and diffusion of water on graphene from first principles

et al. 2011

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Water monomer adsorption on graphene is examined with state-of-the-art electronic structure approaches. The adsorption energy determinations on this system from quantum Monte Carlo and the random-phase approximation yield small values of <100 meV. These benchmarks provide a deeper understanding of the reactivity of graphene that may underpin the development of improved more approximate methods enabling the accurate treatment of more complex processes at wet-carbon interfaces. As an example, we show how dispersion-corrected density functional theory, which we show gives a satisfactory description of this adsorption system, predicts that water undergoes ultra-fast diffusion on graphene at low temperatures.

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Ab initio model study on a water molecule between graphite layers

Cited by 32 publications

References 24 publications

Friction and a Tribochemical Reaction between Ice and Hexagonal Boron Nitride: A Theoretical Study

Friction and a Tribochemical Reaction between Ice and Hexagonal Boron Nitride: A Theoretical Study

Organic nitrogen chemistry during low-grade metamorphism

Adsorption and diffusion of water on graphene from first principles

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