Structure Sensitivity of Acetophenone Reduction on Palladium-Modified Platinum Single-Crystal Electrodes

Abstract

The electrochemical reduction of acetophenone has been investigated in acidic conditions on the three low-index [namely (111), (110), and (100)] single-crystal platinum electrodes coated with an atomic monolayer of palladium. The adsorption and reactivity of some of the acetophenone derivatives, including benzene and acetone, within the same potential window have been compared in order to evaluate the individual reactivity of isolated functional groups and therefore possible reduction of byproducts. The selectivity and faradaic efficiency of the electrocatalytic hydrogenation (ECH) of acetophenone have been determined at selected potentials. The PdMLPt(110) is the most active surface for acetophenone hydrogenation with ca. 50% current efficiency; the other two facets are less active because of a self-poisoning process, the origin of which has not been fully resolved. The only product observed, on all three electrodes, is 1-phenylethanol. Benzene and acetone do not show significant reduction activity on these electrodes. Finally, we compare the activity trends of acetophenone and its derivatives toward ECH to those reported for platinum electrodes, showing that Pd is totally selective for the production of 1-phenylethanol, whereas Pt [especially Pt(100)] shows certain selectivity toward hydrogenolysis byproducts as well.