(Invited) Electrocatalytic Activity Towards ORR and Stability of Binary and Ternary Catalysts Based on Pt and Cu

Abstract

The catalytic activity of platinum can be enhanced by modifying Pt-NPs with transition metal atoms such as Ni, Fe, Co, Cr, Cu [1,2]. But, it has also been proposed that the addition of non-noble transition metals could involve a lower stability than pure platinum due to their dissolution [3,4] leading further to a loss of performances in PEMFC. Other authors have shown that the dealloying of the nanoparticle surface, leading to a core-shell structure having a Pt rich surface, could enhance the catalytic activity of binary or ternary Pt-based systems. On the one hand, gold was proposed to prevent platinum dissolution by raising the Pt oxidation potential [5,6], a property which could be interesting to enhance the stability of core-shell Pt-based catalysts with Pt rich surface. Moreover, it has also been shown that PtAu-based catalysts could exhibit similar or even higher catalytic activity towards ORR than pure platinum [7–9]. On the other hand, recent DFT calculation identified that copper containing Pt-based catalysts, such as PtAuCu core-shell structures, as displaying high expected ORR activity and also a stabilizing effect from the Au-Cu interaction [10]. For these reasons, PtxCu1-x/C and ternary PtxAuyCuz/C catalysts were synthesized by a microemulsion method and characterized by TGA, TEM, XRD, AAS, XPS and cyclic voltammetry in order to assess their metal loading, their microstructure and their bulk and surface compositions. The electrocatalytic activity towards ORR, the selectivity and the stability of catalysts were studied in acidic electrolyte using the rotating disc and the rotating ring disc electrode techniques. Acknowledgement: The financial support of the European Commission under the FP7 Fuel Cells and Hydrogen Joint Technology Initiative grant agreement FP7-2012-JTI-FCH-325327 for the SMARTCat project is gratefully acknowledged.