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

Abstract

The reactivity of layered PdTe₂ toward methanol (CH₃OH) decomposition was promoted by surface under-coordinated Pd (denoted as Pd_uc) generated by removing surface Te with controlled Ar ion bombardment. Methanol on the Pd_uc sites at surface Te vacancies decomposed through competing dehydrogenation and C–O bond cleavage processes; approximately 26% of methanol was converted to CH_x* and 17% to CH_xO* (* 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 Pd_uc; 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 CH_x* was preferentially hydrogenated. Our results suggest that a PdTe₂ surface with Pd_uc at surface Te vacancies can serve as an efficient catalyst toward methanol decomposition and against carbon poisoning.