Enhancing C–C Bond Scission for Efficient Ethanol Oxidation using PtIr Nanocube Electrocatalysts

Abstract

Ethanol is a green, sustainable, and high-energy-density liquid fuel that holds great promise for direct liquid fuel cells (DLFCs). However, it remains highly challenging to develop electrocatalysts that selectively promote the C–C bond scission for the ethanol oxidation reaction (EOR). Here, we report the facile synthesis of PtIr alloy core–shell nanocubes (NCs) with Ir-rich shells as effective EOR electrocatalysts. We find that (100)-exposed Pt38Ir NCs with one-atom-thick Ir-rich skin exhibit unprecedented EOR activity, high CO2 selectivity, and long-term stability, while pure Pt NCs and Pt17Ir NCs (two-atom thick Ir-rich skin) show less activity and lower CO2 selectivity. We demonstrate that the Pt38Ir NCs electrocatalyst can deliver a current density up to 4.5 times higher than that of Pt/C with a lower EOR onset potential by 320 mV. Its CO2 current density at 0.85 V is 14 times higher than that of commercial Pt/C. We show that the enhanced EOR activity is mainly due to the Ir-rich PtIr(100) facet that not only favors the splitting of the C–C bond by strongly adsorbing the *CxHyO/CxHy species but also promotes the desorption of CO from the PtIr surface. This work highlights the critical role of surface atom layers on shape-engineered catalysts and demonstrates a strategy for the design of efficient EOR electrocatalysts.