THE REACTIVITY OF SULFUR-CONTAINING MOLECULES ON NOBLE-METAL SURFACES .3. ETHANETHIOL ON AU(110) AND AG(110)

The adsorption of ethanethiol on clean and partially sulfided Au(110) and Ag(110) surfaces has been investigated using temperature programmed reaction spectroscopy. In all cases a portion of the adsorbed ethanethiol undergoes S-H bond cleavage below 350 K to form ethyl thiolate; H-2 and H2S are evolved between 150 and 350 K. Ethyl thiolate decomposes above 400 K on Ag(110) to yield ethylene, together with ethane and some dihydrogen. On Au(110) ethyl thiolate decomposes in the same temperature range to evolve a mixture of ethylene, ethane, ethanethiol and diethyl sulfide. The evolution of sulfur-containing molecules from thiolate decomposition is novel and appears to be unique to gold. On both surfaces the decomposition kinetics are dependent on surface sulfur coverage.