Free–templated synthesis of N–doped PtCu porous hollow nanospheres for efficient ethanol oxidation and oxygen reduction reactions

Abstract

Hollow metal–based nanoparticles usually possess improved electrocatalytic properties, but challenge in their tedious and complicated synthetic protocols. In this paper, a one–step template–free method is newly developed, whereby the N–doped PtCuCo polycrystalline nanospheres can be spontaneously transformed to the N–doped PtCuCo porous hollow nanospheres. Specifically, the Kirkendall voids form with the rapid removal of transition metals in the starting nanoparticles by a special diffusion–oxidation–complexation effect. The N–doped Pt7Cu hollow nanospheres with ultrathin porous shells are formed after removing the surface oxides. A large electrochemical surface area of 97.9 m2 gPt–1 is established with the formation of abundant open channels in the hollow nanospheres. With the synergetic effect of the introduction of Cu, N components and the high Pt utilization, the N–doped Pt7Cu porous hollow nanospheres demonstrate greatly enhanced electrocatalytic mass activities of 2.14 A mgPt–1 and 1.42 A mgPt–1 toward ethanol oxidation and oxygen reduction reactions, respectively.