Enhancement of Selective Decomposition: Adsorption anf Reaction of Methanethiol on Carbon-Covered W(001)

Article abstract of DOI:10.1021/j100015a044

Selective decomposition of methanethiol (CH3SH) on carbon-covered W(001) to produce mathane is enhanced by 75percent compared to the clean surface.The maximum enhancement requires only 0.25 monolayers (ML) of preadsorbed C.On a surface percovered with 0.8 ML of C, the methane desorbs in peaks at 460 and 550 K compared to 360 K on the clean surface, suggesting a greater stability in the C-S and C-H bonds.Increased intramolecular bond stability is confirmed by the temperature dependence of the S 2p and C ls soft X-ray photoemission.Methyl thiolate, CH3S, forms upon adsorption at 100 K.Chemisorbed methanethiol, which is not stable on the clean surface, is also observed between 100 and 300 K.The chemisorbed thiol decomposes to form additional thiolate.The thiolate reacts along three competing pathways.It undergoes rehydrogenation and desorbs as methanethiol, it selectively decomposes to form desorbed methane and adsorbed S, or it totally decomposes to form S, C, and desorbed H2.