An etching approach to bimetal-doped hollow carbon nanospheres with boosted oxygen reduction reaction

Incorporation of two or more types of metallic atoms into carbon matrix is of particular interest in the fabrication of high performance electrode materials. This normally requires complex synthetic routes or intricate post-processing process. Moreover, the composition and morphology of the resultant carbon materials are uncontrollable. Herein, we show the first time that a bimetal ions (Sn 4+ and Fe 3+ ) etching method based on Kirkendall effect can transform boronate polymer assemblies into metallosupramolecular polymer hollow spheres, which can be carbonized into carbon shells comprising FeSn 2 alloy. The carbon shells display evidently improved activity towards oxygen reduction reaction with onset potential 0.94 V and half-wave potential 0.84 V vs. RHE, which are comparable to that of Pt/C. The as formed FeSn 2 alloy in the carbon matrix possesses characteristics of rich in electrons, excellent conductivity and high chemical activity. Our supramolecular approach is simple, and able to control both the composition and morphology of the carbon materials, which may afford a new strategy for the design of higher performance electrochemical catalysts.