Rhombohedral Pd–Sb Nanoplates with Pd‐Terminated Surface: An Efficient Bifunctional Fuel‐Cell Catalyst

Abstract

Developing high-performance electrocatalysts for both ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) is essential for the commercialization of direct ethanol fuel cells (DEFCs), but it is still formidable challenging. Herein, for the first time we have successfully prepared a novel Pd-Sb hexagonal nanoplate for boosting both cathodic and anodic fuel cell reactions. Detailed structural characterizations reveal that the nanoplates have ordered rhombohedral phase of Pd8 Sb3 (denoted as Pd8 Sb3 HPs) with Pd-terminated surface. Significantly, the unique Pd8 Sb3 HPs can exhibit much enhanced activity towards the oxidation of various alcohols in alkaline media. In particular, Pd8 Sb3 HPs/C displays superior specific and mass activities of 29.3mA cm-2 and 4.5 A mgPd -1 towards EOR, which are 7.0 and 11.3 times higher than those of commercial Pd/C, and 9.8 and 3.8 times higher than those of commercial Pt/C, respectively, representing one of the best EOR catalysts reported to date. In-situ electrochemical ATR-SEIRAS measurements reveal that Pd8 Sb3 HPs/C can effectively promote the C2 pathway of EOR, which is the key to the improved activity. As further disclosed by the density functional theory calculations, the higher EOR intrinsic catalytic activity of Pd8 Sb3 HPs can be ascribed to the reduced energy barrier of ethanol dehydrogenation. In addition, Pd8 Sb3 HPs/C can also show superior performance to both commercial Pd/C and Pt/C in cathodic ORR. This work advances the controllable synthesis of Pd-Sb nanostructure, which give huge impetus to the design of high-efficiency bifunctional electrocatalysts for energy conversion and beyond. This article is protected by copyright. All rights reserved.