Glycerol electro-oxidation on bismuth-modified platinum single crystals

Herein we describe the role of Bi adatom irreversibly adsorbed on platinum single-crystal electrodes toward the oxidation of glycerol. Our results show that the presence of bismuth on the Pt(1 1 1) electrode improves the activity of the reaction, by preventing the adsorption of poisoning intermediates such as carbon monoxide, as well as the selectivity to dihydroxyacetone, while on the Pt(1 0 0)/Biir electrode, the presence of a strongly bound glycerol-related adsorbate and a small amount of linearly bonded carbon monoxide causes a decrease in the activity. Significantly, the presence of bismuth on Pt(1 0 0) does not change its tendency to produce only glyceraldehyde as the primary product of the oxidation of glycerol. The increase in the selectivity to DHA on Pt(1 1 1)/Biir is attributed to the interaction of the Bi adatom with the enediol intermediate, an adsorbed intermediate that exists on Pt(1 1 1) but not on Pt(1 0 0). The enediol is the key intermediate in the isomerization reaction between glyceraldehyde and dihydroxyacetone, and the stabilization of this intermediate by the interaction with the bismuth enhances the rate of the isomerization reaction toward the thermodynamically most stable isomer, namely dihydroxyacetone.