Improved oxygen reduction reaction via a partially oxidized Co-CoO catalyst on N-doped carbon synthesized by a facile sand-bath method

摘要

High active and durable non-noble metal electrocatalysts are urgently developed to satisfy the high performance oxygen reduction reaction(ORR). We successfully synthesized Co-CoOx anchored on nitrogen-doped carbon via a facile sand-bath method(SBM), i.e., Co-CoOx/N-C(SBM). The as-obtained Co-CoOx/N-C(SBM) exhibited overwhelming superiorities to Co-CoO/N-C prepared by conventional heat treatment(CHT), particularly in electrochemical performance of ORR. Although Co-CoOx/N-C(SBM)showed smaller specific surface area of 276.8 m^2/g than that of 939.5 m^2/g from Co-CoO/N-C(CHT), the Co-CoOx/N-C(SBM) performed larger pore diameter and more Co_3O_4 active component resulting in better ORR performance in 0.1 mol/L KOH solution. The Co-CoO_x/N-C(SBM) delivered onset potential of 0.91 V vs. RHE, mid-wave potential of 0.85 V vs. RHE and limited current density of 5.46 mA/cm^2 much better than those of the Co-CoO/N-C(CHT). Furthermore, Co-CoOx/N-C(SBM) showed greater stability and better methanol tolerance superior to the commercial 20 wt% Pt/C.