Highly Dispersed Mo Sites on Pd Nanosheets Enable Selective Ethanol-to-Acetate Conversion.

The fermentation of biomass allows for the generation of major renewable ethanol biofuel that has high energy density favorable for direct alcohol fuel cells in alkaline media. However, selective conversion of ethanol to either CO or acetate remains a great challenge. Especially, the ethanol-to-acetate route usually demonstrates decentoxidation current density relative to the ethanol-to-CO route that contains strongly adsorbed poisons. This makes the total oxidation of ethanol to CO unnecessary. Here, we present a highly active ethanol oxidation electrocatalyst that was prepared by in situ decorating highly dispersed Mo sites on Pd nanosheets (MoO/Pd) via a surfactant-free and facile route. We found that ∼2 atom % of Mo on Pd nanosheets increases the current density to 3.8 A mg, around 2 times more active relative to the undecorated Pd nanosheets, achieving nearly 100% faradic efficiency for the ethanol-to-acetate conversion in an alkaline electrolyte without the generation of detectable CO, evidenced by in situ electrochemical infrared spectroscopy, nuclear magnetic resonance, and ion chromatography. The selective and CO-free conversion offers a promising strategy through alcohol fuel cells for contributing comparable current density to power electrical equipment while for selective oxidation of biofuels to useful acetate intermediate for the chemical industry.