Carbon Deposition and Permeation on Nickel Surfaces in Operando Conditions: A Theoretical Study

TY Lei and JT Mao and XC Liu and AD Pathak and S Shetty and AP van Bavel and L Xie and R Gao and PJ Ren and D Luo and QY Liu and W Ma and CL Xu and XD Wen, JOURNAL OF PHYSICAL CHEMISTRY C, 125, 7166-7177 (2021).

DOI: 10.1021/acs.jpcc.0c11292

The carbon deposition and permeation on nickel surfaces were investigated from thermodynamic and kinetic aspects by using density functional theory (DFT), ab initio atomic thermodynamics, and classical molecular dynamics (MD) simulations. The resulting evolution of particle morphology, crystalline composition, and barriers of typical surface reactions were explored. The exposed facets of Ni show distinct thermodynamic and kinetic sensitivity to carbon deposition and permeation. Thermodynamically, with increasing carbon chemical potential, the carbon coverage and the surface energies of facets change, which leads to the evolving of the equilibrium morphology of Ni particles, favoring higher exposure of the (111) surface. MD simulations show that carbon deposition triggers surface reconstruction at high temperature, and the rate of carbon permeation increases with temperature. Kinetically, the permeation on most Ni surfaces is facile at relatively low temperature except for (111), which shows a threshold temperature of 800 K. Evaluation of a representative probe reaction (methane activation) shows that the reaction barrier and reaction energy increase with the degree of carbide formation, while no general trend is observed for the reverse reaction (CH3 + H). Our study provides an atomic level insight into the carbon deposition process on Ni surfaces and indicates that it is crucial to consider carbon deposition and permeation to understand the particle morphology, crystalline composition, and catalytic performances of Ni.

Return to Publications page