Pt–Co@Pt Octahedral Nanocrystals: Enhancing Their Activity and Durability toward Oxygen Reduction with an Intermetallic Core and an Ultrathin Shell
Minghao Xie, Zhiheng Lyu, Ruhui Chen, Min Shen, Zhenming Cao, Younan Xia
Abstract
Despite extensive efforts devoted to the synthesis of Pt–Co bimetallic nanocrystals for fuel cell and related applications, it remains a challenge to simultaneously control atomic arrangements in the bulk and on the surface. Here we report a synthesis of Pt–Co@Pt octahedral nanocrystals that feature an intermetallic, face-centered tetragonal Pt–Co core and an ultrathin Pt shell, together with the dominance of {111} facets on the surface. When evaluated as a catalyst toward the oxygen reduction reaction (ORR), the nanocrystals delivered a mass activity of 2.82 A mg–1 and a specific activity of 9.16 mA cm–2, which were enhanced by 13.4 and 29.5 times, respectively, relative to the values of a commercial Pt/C catalyst. More significantly, the mass activity of the nanocrystals only dropped 21% after undergoing 30 000 cycles of accelerated durability test, promising an outstanding catalyst with optimal performance for ORR and related reactions.