Nanomaterials for Fuel Cell Catalysis by Kenneth I. Ozoemena & Shaowei Chen

Author:Kenneth I. Ozoemena & Shaowei Chen
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

In addition, given that the lattice strain effect on the surface was considered as the main reason for the enhanced activity, another significant calculation was also conducted to find the relationship between the oxygen binding energy (denoted as AE in Fig. 7.9) and the lattice strain on the surface described as the ratio of lattice constant, as shown in Fig. 7.9. According to Fig. 7.9, the relationship is linear and the reduced lattice ratio on the surface is supposed to benefit the catalytic activity. It is also predicted that Fe would be a better alloy element than Co for interfacial engineering of Pd for a better catalytic performance, and the activity of Pd11Fe alloy may be as comparable to that of Pt since the oxygen binding energy on it is very close to that on Pt, based on the relationship. Such a prediction, as a matter of fact, was confirmed by Shao et al. [15]. They prepared a serial of Pd-Fe alloys with different atomic ratios and found a volcano relationship between the activity and the atomic ratio. It was reported that different alloying degree of Fe resulted in different Pd-Pd bond length, generating different lattice strain, further altering the d-band center position of the alloy, which determined the surface activity of the alloy. Moreover, the Pd3Fe was found to be very stable, methanol tolerated, and exhibit even higher activity than Pt.

Fig. 7.9Relationship between the AE of Oads and the strain ratio in the lattice constant of Pd, which may serve as a guideline for the design of Pd-alloy catalysts for ORR. Reprinted with permission from (Suo YG, Zhuang L, Lu JT: First-principles considerations in the design of Pd-alloy catalysts for oxygen reduction. Angew Chem Int Edit 2007, 46, 2862–2864. Copyright © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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