Decomposition of methanol activated by surface under-coordinated Pd on layered PdTe2.

The reactivity of layered PdTe2 toward methanol (CH3OH) decomposition was promoted by surface under-coordinated Pd (denoted as Pduc) generated by removing surface Te with controlled Ar ion bombardment. Methanol on the Pduc sites at surface Te vacancies decomposed through competing dehydrogenation and C-O bond cleavage processes; approximately 26% of methanol was converted to CHx* and 17% to CHxO* (* denotes adspecies; x = 2 and 3) as major intermediates at 180 K, leading to a reaction probability of >40% and an ultimate gaseous production of molecular hydrogen, formaldehyde, methane and water. The characteristic reactivity arose from both geometric and electronic effects-the hexagonal-lattice positioning and partial oxidation of the Pduc; its comparison with that of PtTe2 surface emphasized the critical role of electronic structures in determining the reactivity and selectivity. Notably, these reaction processes produced scarce C* as the intermediate CHx* was preferentially hydrogenated. Our results suggest that a PdTe2 surface with Pduc at surface Te vacancies can serve as an efficient catalyst toward methanol decomposition and against carbon poisoning.