Pt-Zn Nanocube for Enhanced Mass and Specific Activities in Ammonia Electro-Oxidation Reaction (AOR)

Abstract

Many studies have revealed that only platinum and iridium can selectively oxidize ammonia to nitrogen, as the two combines a good dehydrogenation capacity with a sufficiently low affinity for the poison Nads [1]. While platinum is expensive, one effective approach to reduce platinum loading and increase catalytic activity is alloying platinum with other metals and forming binary or ternary alloys. In one research, Jiang [2] introduced zinc into platinum and iridium electrode by electrodeposition and demonstrated an increase of ammonia electro-oxidation reaction (AOR) catalytic activity. In this study, Pt-Zn cubic nanoparticles were synthesized and loaded onto carbon black. The shape of Pt-Zn nanoparticles was mostly cubic illustrated by TEM images and the atomic ratio of Pt to Zn was around 4 to 1 according to ICP-OES. These Pt-Zn nanoparticles exhibited an improvement in AOR activity compared with cubic Pt nanoparticles and commercial Pt nanoparticles normalized to ECSA, termed specific activity, as shown in figure 1. The AOR peak current of Pt-Zn nanoparticles specific activity was 2.15*10-3 A/cm2 which is 1.1 and 17.1 times higher than cubic Pt and commercial Pt nanoparticles respectively. The possible reasons for increase of AOR activity will be discussed in detail. Reference [1] A. C. A. de Vooys, M. T. M. Koper, R. A. Van Santen and J. A. R. Van Veen, J. Electroanal. Chem., 2001, 506, 127–137. [2] J. Jiang, Electrochemistry Communications, 75 (2017) 52-55. Figure 1