Towards an Efficient and Stable Pt-alloy Electrocatalyst for Direct Isopropanol Fuel Cell
Résumé
The growing concern over liquid organic hydrogen carriers (LOHCs) has made direct isopropanol (IPA) fuel cells (DIFCs) an attractive technology. DIFCs do not to emit CO2 while producing only acetone 1 . Interestingly, acetone can be reused for the hydrogenation of LOHCs via hydrogen transfer between acetone and IPA. However, the IPA electrooxidation faces a problem with deactivation over Pt/C catalyst at high potentials 2 . Developing Pt-alloy catalysts is an alternative approach to solve the issue. We synthesized PtSn, PtRu and PtSnRu using a simple polyol method. TEM images and EDX mapping (Fig.1A) confirmed the crystal structure characteristics and elemental distribution of PtRu and PtSn. Each nanoparticle (NP) clearly incorporates a homogenous solid solution rather than individual metal NPs. Additionally, the synthesis process can successfully control the mean NP size with a variation of ± 2 nm. Cyclic voltametries (CV, Fig.1B) show that Ru-containing samples are the most active for IPA oxidation below 0.3 V. The overall charge derived from the chronoamperometry (CA) experiments confirm this finding at 0.3 V (Fig.1 D). The overall charge is maximal at 0.7 V for Pt-alloys and 0.6 V for the Pt-only sample (Fig. 1D). While PtSn produces the highest charge at high potentials, PtSnRu sample combines the effects of Sn and Ru on the IPA oxidation. Moreover, CA experiments at 0.8 V (Fig 1C) show a slightly better stability of PtSn and PtSnRu (higher current densities at the end of the CA). Sn addition might be responsible for overcoming the poisoning effect by showing faster acetone desorption kinetics. These results emphasize the paramount importance of Pt-alloy materials for tailoring active and stable electrocatalyst for DIFCs. Acknowledgements The authors thank the French National Agency for funding the SAFHYR project (grant N° ANR-21- CE50-0045). References [1] G. Sievi, D. Geburtig, T. Skeledzic, P. Khanipour, Energy Environ. Sci. 12. (2019) 2305J. [2] Hauenstein P., Seeberger D., Electrochem. Comm. 9. (2020) 106786.