Shaped Pt-Ni nanocrystals with an ultrathin Pt-enriched shell derived from one-pot hydrothermal synthesis as active electrocatalysts for oxygen reduction

• Published in: Nano research Vol. 8; no. 5; pp. 1480 - 1496
• Main Authors: Gu, Jun, Lan, Guangxu, Jiang, Yingying, Xu, Yanshuang, Zhu, Wei, Jin, Chuanhong, Zhang, Yawen
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.05.2015; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemistry and Materials Science; Condensed Matter Physics; Materials Science; Nanocrystals; Nanotechnology; Research Article; X射线光电子能谱分析; 比活性; 氧还原反应; 水热合成; 电催化剂; 纳米晶体; 铂原子; 镍合金; Pt-NiPt-Ni alloy nanocrystals; aqueous-phase synthesis; dealloying; bimetallic catalysts; oxygen reduction reaction
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-014-0632-7

Alloy nanocrystals （NCs） of Pt with 3d transition metals, especially Ni, are excellent catalysts for the oxygen reduction reaction （ORR）. In this work, we, for the first time, demonstrated the water phase colloidal synthesis of Pt-M （M = Ni, Co and Fe） alloy NCs with tunable composition and morphology through a facile hydrothermal method. Pt-Ni alloy NCs synthesized with this method presented better ORR activity than commercial Pt/C catalysts. The X-ray energy dispersive spectra （EDS） mapping technique revealed that Pt-enriched shells existed on the as-synthesized Pt-Ni alloy NCs. About two atom thick layered Pt-enriched shells formed on Pts0Nis0 NCs and the thickness of the Pt-enriched shells increased as the Ni content increased. Furthermore, X-ray photoelectron spectroscopy analysis revealed that the oxidation level of the surface Pt atoms on the Pt-Ni alloy NCs decreased compared with monometallic Pt NCs, implying a decrease in the oxophilicity of the surface Pt atoms. Pt-Ni alloy NCs with lower oxophilicity of the surface Pt atoms give higher ORR activity. The most active alloy sample showed 13 times higher specific activity and six times higher mass activity at 0.9 V vs. a reversible hydrogen electrode when compared with commercial Pt/C. Pt-Ni alloy NCs also showed better durability than commercial Pt/C in long term ORR tests.