Site requirements for the reactions of CH3SH and (CH3)2S2 on ZnO(101¯0)

Temperature programmed desorption (TPD) was used to investigate the adsorption and reaction of CH3SH and (CH3)2S2 on the nonpolar (101¯0) surface of ZnO. Methanethiol was found to dissociate on the (101¯0) surface to produce adsorbed methylthiolates. The primary reaction pathways for the methylthiolates were methyl group transfer between adjacent thiolates to produce (CH3)2S at 510 K, and transfer of methyl groups to surface lattice oxygen to produce adsorbed methoxides which were oxidized to CH2O at 525 K and adsorbed formate. Dimethyldisulfide was found to dissociate via cleavage of the S-S bond to form adsorbed methylthiolates. The reaction pathways for thiolates produced in this manner were similar to those produced from CH3SH except for an additional low-temperature pathway for the production of CH2O. Comparison of the results obtained in this study to our previous study of the reaction of CH3SH and (CH3)2S2 on ZnO(0 0 0 1) and published STM studies of ZnO(101¯0) and ZnO(0 0 0 1) indicates that step edges are the active sites for the reaction of thiols and disulfides on these surfaces.