Templated synthesis of cobalt subnanoclusters dispersed N/C nanocages from COFs for highly-efficient oxygen reduction reaction

Development of nonprecious metal-based electrocatalysts with highly efficient oxygen reduction reaction (ORR) has increasingly attracted wide attention in energy conversion and storage systems. In this work, we stepwise grow cobalt chelated COF TpBpy (Co-TpBpy) on silica nanospheres to form core-shell SiO2@Co-TpBpy nanospheres. After calcination high temperatures and removing silica template, cobalt subnanoclusters dispersed in N-doped carbon (N/C) nanocages are obtained for ORR. As a result, the Co-TpBpy-800 nanocages exhibit highly efficient activity on electrocatalytic ORR with 0.831 V of half-wave potential and high stability. Moreover, DFT calculation verifies the resulting unique nanocages reveal an unconventional five-step ORR process in which it skips the intermediate OOH* because the oxygen dissociation and adsorption directly occur on the catalyst surface. The present work will help the development of highly-efficient nonprecious metal-based catalysts for various energy applications.