Density functional theory studies of methane dissociation on anode catalysts in solid-oxide fuel cells: Suggestions for coke reduction

We studied the dissociation of methane into adsorbed carbon and hydrogen atoms on various surfaces to gain insight into carbon coke formation on solid-oxide fuel cell anodes. Preferred adsorption sites and energies were calculated for CHxCHx (x=0,…,3x=0,…,3) and H on Ni and Cu (111) planar and (211) stepped surfaces, on CuNi and CuCo surface alloys, and on Ni(211) surfaces with step edge sites blocked by Au- and S-promoter atoms. Transition states and kinetic barriers were calculated on Cu(111) and Cu(211) and on the SNi(211) surface. Our results are in excellent agreement with existing experimental and theoretical studies, suggesting that copper anodes have very low activity and high resistance to coking, and that step-blocking on the nickel surface can increase the tolerance of nickel-based anodes to carbon coke formation.