Adsorption Behaviors of Cobalt on the Graphite and SiC Surface: A First-Principles Study

Graphite and silicon carbide (SiC) are important materials of fuel elements in High Temperature Reactor-Pebble-bed Modules (HTR-PM) and it is essential to analyze the source term about the radioactive products adsorbed on graphite and SiC surface in HTR-PM. In this article, the adsorption behaviors of activation product Cobalt (Co) on graphite and SiC surface have been studied with the first-principle calculation, including the adsorption energy, charge density difference, density of states, and adsorption ratios. It shows that the adsorption behaviors of Co on graphite and SiC both belong to chemisorption, with an adsorption energy 2.971 eV located at the Hollow site and 6.677 eV located at the hcp-Hollow site, respectively. Combining the charge density difference and density of states, it indicates that the interaction of Co-SiC system is stronger than Co-graphite system. Furthermore, the variation of adsorption ratios of Co on different substrate is obtained by a model of grand canonical ensemble, and it is found that when the temperature is close to 650 K and 1700 K for graphite surface and SiC surface, respectively, the Co adatom on the substrate will desorb dramatically. These results show that SiC layer in fuel element could obstruct the diffusion of Co effectively in normal and accidental operation conditions, but the graphite may become a carrier of Co radioactivity nuclide in the primary circuit of HTR-PM.

[1]  Somers,et al.  Identification of the s-derived valence-electron level in photoemission from alkali-metal adlayers on aluminum. , 1988, Physical review letters.

[3]  Boettger,et al.  Interplanar binding and lattice relaxation in a graphite dilayer. , 1992, Physical review. B, Condensed matter.

[4]  E. Tok,et al.  Density functional theory study of Fe, Co, and Ni adatoms and dimers adsorbed on graphene , 2009 .

[5]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[6]  F. Marinelli,et al.  Density functional theory investigation of the diffusion and recombination of H on a graphite surface , 2003 .

[7]  Jian-Bo Deng,et al.  Density functional calculation of transition metal adatom adsorption on graphene , 2010 .

[8]  Lizhi Wang.  Adsorption of formaldehyde (HCOH) molecule on the SiC sheet: A first-principles study , 2012 .

[9]  D. Langreth,et al.  Van Der Waals Interactions In Density Functional Theory , 2007 .

[10]  N. A. Cordero,et al.  Interaction of lithium with graphene: An ab initio study , 2004 .

[11]  T. Liang,et al.  Adsorption and Electronic Structure of Sr and Ag Atoms on Graphite Surfaces: a First-Principles Study , 2013 .

[12]  S. Aydin,et al.  First-principles study of thiophene on β-SiC (0 0 1)-(2×1) surface , 2011 .

[13]  Citrin,et al.  Alkali metal adsorbates on W(110): Ionic, covalent, or metallic? , 1990, Physical review letters.

[14]  J. Almlöf,et al.  Chemisorption of aluminum atoms on a graphite surface: cluster convergence and effects of surface reconstruction , 1992 .

[15]  R. J. Baierle,et al.  First principles study about Fe adsorption on planar SiC nanostructures , 2014 .

[16]  W. Kohn,et al.  Self-Consistent Equations Including Exchange and Correlation Effects , 1965 .

[17]  E. Schröder,et al.  Adsorption of phenol on graphite(0001) and α-Al2O3(0001): Nature of van der Waals bonds from first-principles calculations , 2006 .

[18]  Elsebeth Schröder,et al.  Application of van der Waals density functional to an extended system: adsorption of benzene and naphthalene on graphite. , 2006, Physical review letters.

[19]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[20]  Liu Yuanzhong,et al.  Fission product release and its environment impact for normal reactor operations and for relevant accidents , 2002 .

[21]  T. Liang,et al.  Study of interaction between radioactive nuclides and graphite surface by the first-principles and statistic physics , 2013 .

[22]  G. Kresse,et al.  Ab initio molecular dynamics for liquid metals. , 1993 .

[23]  Y. Sano,et al.  Adsorption of hydrogen fluoride on SiC surfaces: A density functional theory study , 2012 .

[24]  Sung Ho Park,et al.  A first principles study of NO2 chemisorption on silicon carbide nanotubes , 2009 .

[25]  Jian-min Zhang,et al.  Structural and electronic properties of SiC nanotubes filled with Cu nanowires: A first-principles study , 2013 .

[26]  Norman,et al.  Determination of an adlayer bonding transition by surface extended x-ray-absorption fine-structure spectroscopy: Cesium adsorbed on Ag{111} , 1988, Physical review letters.

[27]  X. Sha,et al.  First-principles study of the structural and energetic properties of H atoms on a graphite (0001) surface , 2002 .

[28]  M. Katsnelson,et al.  Orbitally controlled Kondo effect of Co ad-atoms on graphene , 2009, 0911.2103.

[29]  Palmer,et al.  Electronic structure and phase transitions of submonolayer potassium on graphite. , 1992, Physical review. B, Condensed matter.

[30]  T. Liang,et al.  Adsorption behaviors of Cs and I atoms on the graphite surface by the first-principles , 2013 .

[31]  M. Scheffler,et al.  Initial adsorption of Co on Cu(001): A first-principles investigation , 2002 .

[32]  Chong-yu Wang,et al.  First-principles study of a single Ti atom adsorbed on silicon carbide nanotubes and the corresponding adsorption of hydrogen molecules to the Ti atom , 2007 .

[33]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[34]  M. Katsnelson,et al.  Adsorption of cobalt on graphene: Electron correlation effects from a quantum chemical perspective , 2012, 1206.1222.

[35]  Toigo,et al.  First-principles study of potassium adsorption on graphite. , 1993, Physical review. B, Condensed matter.

[36]  Ishida,et al.  Depolarization and metallization in alkali-metal overlayers. , 1990, Physical review. B, Condensed matter.

[37]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .