Single-atom Pt and bimetallic Pt 3 Co are considered the most promising oxygen reduction reaction (ORR) catalysts, with a much lower price than pure Pt. The combination of single-atom Pt and bimetallic Pt 3 Co in a highly active nanomaterial, however, is challenging and vulnerable to agglomeration under realistic reaction conditions, leading to a rapid fall in the ORR. Here, a sustainable quasi-Pt-allotrope catalyst, composed of hollow Pt 3 Co (H-PtCo) alloy cores and N-doped carbon anchoring single atom Pt shells (Pt 1 N-C), is constructed. This unique nanoarchitecture enables the inner and exterior spaces to be easily accessible, exposing an extra-high active surface area and active sites for the penetration of both aqueous and organic electrolytes. Moreover, the novel Pt 1 N-C shells not only effectively protect the H-PtCo cores from agglomeration but also increase the efficiency of the ORR in virtue of the isolated Pt atoms. Thus, the H-PtCo@Pt 1 N-C catalyst exhibits stable ORR without any fade over a prolonged 10 000 cycle test at 0.9 V in HClO 4 solution. Furthermore, this material can offer efficient and stable ORR activities in various organic electrolytes, indicating its great potential for next-generation lithium–air batteries as well.