Selective electrocatalytic hydrogenation of α,β-unsaturated ketone on (111)-oriented Pd and Pt electrodes

Abstract

In this paper, we study the electrocatalytic reduction of methyl vinyl ketone on Pt(111) and Pd-modified Pt(111) electrodes, as well as some of its expected hydrogenation derivatives and isolated functional moieties. The selectivity and Faraday efficiency have been calculated via sampling the catholyte solution after two hours of electrolysis. Furthermore, the adsorbates involved in the deactivation process on both surfaces were studied by means of potential opening experiments and in situ infrared spectroscopy. The Pd-modified Pt(111) electrode is very active (even mass transport limited) for the selective electrochemical hydrogenation of the C=C to 2-butanone, in the hydrogen underpotential deposition potential window (between 0 and 0.2 VRHE), with limited poisoning. Pt(111) is much less active, and poisons rapidly with adsorbed CO. The poison is formed from the C=C bond, not from the C=O moiety, as evidenced by the same poisoning occurring for ethylene. Further hydrogenation to the saturated alcohol happens at more negative potentials, but with 2-butenol as intermediate, not 2-butanone, as the latter species interacts too weakly with the (111) surface.