Carbon-supported Pt-M (M=Ni or Co) nanoparticles (NPs) have been intensively studied as oxygen reduction reaction (ORR) catalysts for the cathode of polymer electrolyte fuel cells. Under electrocatalytic conditions, these catalysts are known to degrade involving particle detachment, agglomeration and metal dissolution. To develop highly durable ORR electrocatalysts, these phenomena can be suppressed by strong metal/support interactions^[1,2] or even utilized as self-healing or sacrificial processes.

We present the ORR activity, durability and structural transformation of carbon-supported Pt-Ni nanowires (NWs) in the presence and absence of NPs.^[3] In the presence of NPs, NPs were dissolved, and NWs were converted to form branched nanostructures during potential cycles. Because the similar structural transformation of NWs occurred even in the absence of NPs, the structural transformation is an intrinsic phenomenon during potential cycles. Interestingly, the ORR activity increased and the Pt dissolution was suppressed during potential cycles in the co-presence of Pt-Ni NWs and NPs. The electronic and surface structures are also changed before and after potential cycles and will be discussed based on physicochemical measurements including in situ Pt L₃-edge X-ray absorption spectroscopy.

This work was supported by NEDO.

References

[1] M. Kato, K. Ogura, S. Nakagawa, S. Tokuda, K. Takahashi, T. Nakamura, I. Yagi, ACS Omega, 3, 9052–9059 (2018).

[2] M. Kato, R. Nakahoshiba, K. Ogura, S. Tokuda, S. Yasuda, K. Higashi, T. Uruga, Y. Uemura, I. Yagi, ACS Appl. Energy Mater., 3, 6768-6774 (2020).

[3] M. Kato, Y. Iguchi, T. Li, Y. Kato, Y. Zhuang, K. Higashi, T. Uruga, T. Saida, K. Miyabayashi, I. Yagi, ACS Catal., 12, 259-264 (2022).