Deuterium and deuterium sulfide adsorption on MoS 2(0001)

Abstract

The adsorption of deuterium and deuterium sulfide was studied on the MoS 2(0001) basal surface using temperature programmed desorption (TPD) and four-point surface conductivity measurements. Deuterium did not dissociatively adsorb to the basal MoS 2(0001) surface upon exposure, and thus was dissociated with a platinum wire during dosing. D 2 and D 2S were both observed as products following adsorption of dissociated D on the MoS 2(0001) surface. The presence of D 2S as a desorption product demonstrates that lattice sulfur was removed to form anion vacancies on the MoS 2(0001) surface. D 2S TPD experiments on an MoS 2 surface with anion vacancies showed both D 2S and D 2 as desorption products. The presence of D 2 in the D 2S TPD shows that some deuterium sulfide dissociatively adsorbs. Further, the amount of D 2 desorbing was found to decrease as a function of exposure, suggesting that D 2S was leaving sulfur behind to “heal” anion vacancies. The desorption traces resulting from both deuterium and deuterium sulfide exposures were very broad, and are thought to occur via the recombination of two different desorption states. The possible implications of these experiments to HDS catalytic systems are also discussed.