Multiple active components, synergistically driven cobalt and nitrogen Co-doped porous carbon as high-performance oxygen reduction electrocatalyst

摘要

Developing durable and efficient doped-type carbon electrocatalysts with diverse heteroatoms or tran- sition metals for oxygen reduction reaction (ORR) has captured increasing attention for their incredible electrocatalytic properties. However, compared to multiple-atom-doped carbon matrix, the introduction of single-type atoms into carbon skeletons provides little benefit to enhancing ORR activity. On the basis of this consideration, we successfully fabricated a cobalt (Co) and nitrogen (N) dual-doped porous carbon (Co@C-N) hybrid with multiple active sites by a facile strategy of combined hydrothermal reaction with thermolysis. As a comparison, porous nitrogen-doped carbon (C@N) was obtained by a similar method. Electrochemical tests confirm that the Co@C-N-120-900 exhibits the best ORR performance in alkaline media with the positive onset potential (E_(onset)) of 0.956 V vs RHE (only 12 mV more negative than Pt/C), the high half-wave potential (E_(1/2)) of 0.851 V vs RHE (24 mV more positive than 20 wt% Pt/C), superior selectivity (a four-electron-dominant process), and smaller Tafel slope (57 mV dec~(-1) ). Meanwhile, as- synthesized Co@C-N-120-900 catalyst shows greater durability and significantly greater methanol toler- ance than Pt/C catalyst. Our experiments indicate that the better overall ORR performance for Co@C-N-120-900 could be caused by the synergistic effect of multiple active components (single Co atom, Co–N_x and plentiful pyridinic-N), high BET specific surface area (1080 m~2 g~(-1) ) and porous structures. Thus, the Co@C-N-120-900 catalyst is expected to be a cost-efficient and promising electro- catalyst in the field of the sustainable energy application, and this work might provide some directions for fabricating advanced energy storage materials.