Insights into the Pt/Rh(111) interface for direct ethanol fuel cells

摘要

Finding a highly efficient electro-catalyst for ethanol oxidation is the central issue in the use of direct ethanol fuel cells. Recently, fabricating interfacial sites between two phases has been reported as an effective approach to boost the heterogeneous catalytic activity. In this work, a comprehensive understanding of how the Pt/Rh(1 1 1) interface promotes ethanol electro-oxidation for direct ethanol fuel cells at atomic levels is gained by employing density functional theory (DFT) calculations. It is found that the Pt/Rh(1 1 1) interface including (1 1 1) x(1 1 0) and (1 1 1) x(1 0 0) could effectively convert ethanol to CH3CO* and the Rh(1 1 1) surface could activate water at low potentials (< 0.5 V) by forming several ordered surface oxygen-containing species adlayers. Moreover, OH* is identified to be an oxidant and CH3CO* oxidation rate on (1 1 1) x(1 1 0) is faster than that on (1 1 1) x(1 0 0). It is therefore suggested that the (1 1 1) x(1 1 0) interface over Pt/Rh(1 1 1) is the active site for catalyzing ethanol electro-oxidation into CH3COOH. These results highlight the significance of metal/metal interfaces and help screen such interfacial catalysts in the design of highly active catalysts for ethanol electro-oxidation reactions.