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

Abstract

Developing high‐performance electrocatalysts for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is essential for the commercialization of direct ethanol fuel cells, but it is still formidably challenging. In this work, a novel Pd–Sb hexagonal nanoplate for boosting both cathodic and anodic fuel cell reactions is prepared. Detailed characterizations reveal that the nanoplates have ordered rhombohedral phase of Pd8Sb3 (denoted as Pd8Sb3 HPs). The Pd8Sb3 HPs exhibit much enhanced activity toward the oxidation of various alcohols. Particularly, Pd8Sb3 HPs/C displays superior specific and mass activities of 29.3 mA cm−2 and 4.5 A mgPd−1 toward the 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 attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) measurements reveal that Pd8Sb3 HPs/C can effectively promote the C2 pathway of the EOR. As revealed by density functional theory calculations, the high EOR activity of the Pd8Sb3 HPs can be ascribed to the reduced energy barrier of ethanol dehydrogenation. Additionally, Pd8Sb3 HPs/C also shows superior performance in the ORR. This work advances the controllable synthesis of the Pd–Sb nanostructure, giving huge impetus for the design of high‐efficiency electrocatalysts for energy conversion and beyond.

A universal synthesis of ultrathin Pd-based nanorings for efficient ethanol electrooxidation

“…Based on the calculated free energy profiles, it is observed that the second dehydrogenation of ethanol (*CH 3 CHOH → *CH 3 COH) was the rate-determining step (RDS) of the C 2 -path of the EOR. 54–56 Notably, PdBi exhibits a lower free energy demand (0.51 eV) in the RDS relative to that of pure Pd (0.88 eV), verifying that the incorporation of Bi atoms can thermodynamically promote the RDS and thus the C 2 pathway in the EOR. This can be attributed to the redistribution of electron charge and the optimized electronic structure of Pd arising from the alloyed Bi.…”

Wet-chemistry synthesis of two-dimensional Pt- and Pd-based intermetallic electrocatalysts for fuel cells

“…16c shows the CVs of Pd 8 Sb 3 HNP/C, commercial Pd/C, and Pt/C in 0.5 M NaOH containing 0.5 M ethanol with a sweep rate of 50 mV s −1 . 76 A lower onset potential and larger current intensity of Pd 8 Sb 3 HNP/C were observed in comparison with commercial Pd/C and Pt/C, suggesting better anodic electrooxidation activity. Pd 8 Sb 3 HNP/C shows the highest SA of 29.3 mA cm −2 and MA of 4.5 A mg Pd −1 .…”

“…7(a and b). 76 The HAADF-STEM-EDX mappings in Fig. 7b show that the Pd and Sb elements are distributed evenly throughout the whole HNPs.…”

Killing Two Birds with One Stone: Upgrading Organic Compounds via Electrooxidation in Electricity-Input Mode and Electricity-Output Mode

“…The OUR of organic compounds in fuel cells seems to be another fascinating strategy for electrosynthesis for both chambers (with oxygen being reduced to hydroxy peroxide) and electricity. Up to now, various alcohols (e.g., ethanol, ethylene glycol, isopropanol, glycerol and Furfural) [ 32 , 34 , 35 , 36 , 37 ] have been demonstrated to have great potential for effectively upgrading fuel cells. Besides fuel cells, upgrading organic compounds can also be realized in other devices, such as zinc–air batteries [ 33 ].…”