Core-shell Co/CoNx@C nanoparticles enfolded by Co-N doped carbon nanosheets as a highly efficient electrocatalyst for oxygen reduction reaction

The enhancement of oxygen reduction reaction (ORR) catalytic activity of non-precious metal catalysts is extremely desirable but still full of challenges. Here, a novel hybrid, core-shell Co/CoNx@C nanoparticles enfolded by Co-N doped carbon nanosheets was successfully prepared by a facile two-step method, including the formation of well-curved porous carbon nanosheets by a facile sintering of trisodium citrate dehydrate and subsequent introduction of cobalt and nitrogen doping. Owing to the distinctive architecture and the synergistic effects between crystalline Co/CoNx@C nanoparticles and non-crystalline CoNxCy active sites, the resultant Co-N-PC catalyst exhibits an outstanding electrocatalytic activity towards ORR in alkaline media with a half-wave potential of 0.833 V (vs. RHE) and a higher limiting current density of 5.70 mA cm(-2), which is superior to commercial 20 wt% Pt/C. In addition, it also displays better electrochemical durability and stronger methanol tolerance than Pt/C. (C) 2018 Elsevier Ltd. All rights reserved.