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Reactions of PtX+ (X = F, Cl, Br, I) with methane have been investigated at the density functional theory (DFT) level. These reactions take place more easily along the low-spin potential energy surface. For HX (X = F, Cl, Br, I) elimination, the formal oxidation state of the metal ion appears to be conserved, and the importance of this reaction channel decreases in going as the sequence: X = F, Cl, Br, I. A reversed trend is observed in the loss of H2 for X = F, Cl, Br, while it is not favorable for PtI+ in the loss of either HI or H2. For HX eliminations, the transfer form of H is from proton to atom, last to hydride, and the mechanisms are from PCET to HAT, last to HT for the sequence of X = F, Cl, Br, I. One reason is mainly due to the electronegativity of halogens. Otherwise, the mechanisms of HX eliminations also can be explained by the analysis of Frontier Molecular Orbitals. While for the loss of H2, the transfer of H is in the form of hydride for all the X ligands. Noncovalent interactions analysis also can be explained the reaction mechanisms.

Theoretical calculations were performed to investigate the effect of potassium on carbon adsorption and deposition on the Co(111) surface. Cn species are expected, and the C2 dimer may be a critical elementary unit. Increasing the carbon coverage, some carbon atoms may diffuse into the subsurface. However, kinetically, the formation of Cn species is more favorable, and there is no driving force for carbon migrating into the subsurface. With increasing of the carbon concentration, the adsorbed carbons form carbon chains and then graphene sheets parallel to the surface. The potassium promoter has little effect on the most stable configurations but increases the adsorption energy, which can be explained by the decrease in the work function resulting from the electronic effects of the potassium promoter. Potassium promotes carbon deposition and carbonization of the cobalt surface to a certain extent. These results could provide useful information for carbon deposition and cobalt carbide formation.