Hollowed-out octahedral Co/N-codoped carbon as a highly efficient non-precious metal catalyst for oxygen reduction reaction

Nowadays, the design and synthesis of high-performance and low-cost catalysts for oxygen reduction reaction (ORR) still remains a significant challenge. Herein, we develop an efficient strategy that utilizes an octahedral Co(II) complex with 2,6-bis(benzimidazol-2-yl)pyridine (BBP) as the precursor for the synthesis of Co/N-codoped carbon non-precious metal catalyst with unique hollowed-out octahedral structure (Co/N-HCOs). As the favorable structure features, such as the high specific surface area, sufficient active sites and suitable pore structure, the Co/N-HCOs catalyst shows not only highly efficient catalytic activity but also superior stability to commercial Pt/C catalyst for the ORR in alkaline media. Furthermore, the influences of transition metal cations (Co2+, Ni2+, Zn2+, Cu2+ and Mn2+) and anions (CH3COO−, Cl− and NO3−) on the structures of the complex precursors and resulting catalysts are also investigated in detail. The results show that all the reactions of metal cations (Co2+, Ni2+ and Zn2+) with anion CH3COO− can form octahedral complex precursors and catalysts. Thereinto, the formation of the hollowed-out octahedral structure is relied on the metal cation (Co2+) and anion (CH3COO−). The present study provides an efficient strategy to synthesize highly efficient octahedral catalysts.