Metal–polydopamine frameworks and their transformation to hollow metal/N-doped carbon particles

We present a new strategy for in situ transformation of metal-organic framework (MOF) crystals to hollow metal-organic structures through polycondensation of dopamine. The hollow metal-polydopamine (PDA) particles are formed by a coordination assembly of metal ions (Co and Zn) and PDA, inheriting the morphology of MOF (ZIF-67 and ZIF-8) crystals. The hollow porous metal/N-carbon particles morphosynthetically transformed from hollow metal-PDA particles exhibit excellent oxygen reduction electrocatalytic activity. The strategy presented here is promising for synthesizing hollow metal-organic polymer (metal-carbon) particles with diverse morphologies for energy and environmental applications.