Facile Route for the Preparation of Ordered Intermetallic Pt3pb-Ptpb Core-Shell Nanoparticles and Its Enhanced Activity for Alkaline Methanol and Ethanol Oxidation
Authors: Matsumoto Futoshi , Gunji Takao , Tanabe Toyokazu , Kaneko Shingo , Ohsaka Takeo 
Published: February 2020

Recently, a new approach that avoids the problems inherent in disordered alloy catalysts has been proposed for highly active electrocatalysts for fuel cell applications [1]. In contrast with disordered alloys, intermetallic compounds with definite compositions and structures, such as PtPb and PtBi, exhibit excellent electrocatalytic performance towards FA oxidation in acidic solutions in terms of onset potential and current density [2]. Abruña et al. have examined the FA, MeOH, and EtOH oxidation activities with a wide range of intermetallic compounds (PtPb, PtBi, and Pt3Ti) in acidic media and found that the intermetallic compounds exhibit enhanced catalytic activity when compared with pure Pt [3]. In our previous study, we reported that PtPb and PtBi ordered intermetallic compounds exhibited higher electrocatalytic activity towards MeOH and EtOH oxidation in alkaline aqueous solutions than Pt, Pt-Ru alloy, and other Pt-based ordered intermetallic compounds [4]. In this paper, we report on the enhancement of the electrocatalytic activity of PtPb ordered intermetallic compounds towards MeOH and EtOH oxidation in alkaline aqueous solutions. To achieve this, carbon black (CB)-supported Pt3Pb(core)-PtPb(shell) intermetallic NPs (Pt3Pb-PtPb NPs/CB) were synthesized via a method (hereafter referred to as the “converting reaction method”) in which the CB-supported Pt NPs react with a Pb precursor in the presence of a reducing agent under microwave irradiation. In the converting reaction method, the Pb atoms were only observed in the PtPb NPs and not on the CB surfaces. In other words, Pb NPs were not formed on CB in the reaction with microwaves, indicating the selective reaction of Pb atoms with Pt NPs on the CB surfaces, as previously reported by Bauer and our group [5]. By controlling the amount of Pb atoms, the core-shell structure with Pt3Pb and PtPb intermetallic phases can be formed in a NP. The activities of Pt3Pb-PtPb NPs/CB were compared with those of the reference samples consisting of pure PtPb NPs/CB and Pt3Pb NPs/CB, which were prepared on the CB through the co-reduction reaction of the Pt and Pb precursors in the presence of a reducing agent and CB (hereafter referred to as the “co-reduction reaction method”). As mentioned above, previously, we have reported that PtPb and PtBi ordered intermetallic phases are the most promising electrocatalysts for MeOH and EtOH oxidations via the exhaustive screening of the ordered intermetallic phases for alkaline MeOH and EtOH oxidations [4]. In this research, our current results obtained with Pt3Pb-PtPb NPs/CB were compared with that of works mentioned above.

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