The Vital Balance of Graphitization and Defect Engineering for Efficient Bifunctional Oxygen Electrocatalyst Based on N-doping Carbon/CNT Frameworks

Defects modulation generally has significant influence on the electronic structures and surface chemistry of porous carbon for the electrocatalysts. Here, nitrogen-doped hierarchical porous carbon/N-CNTs frameworks (Co@NC-m) with the vital graphitization and defect engineering, which encapsulated with cobalt nanoparticles and fabricated by a simple carbonization of Co/Zn zeolitic benzimidazole framework. The as-prepared optimal Co@NC-0.75 shows outstanding catalytic performance for both ORR and OER, the potential gap between the ORR potential with a current density of -3mAcm(-2) and the OER potential with a current density of 10 mA cm(-2) is 0.78V, illustrating that it is one of the best MOFs-derived bifunctional oxygen electrocatalysts reported to date. More importantly, the Co@NC-0.75 demonstrates comparable catalytic performance and durability to those of commercial Pt/C for ORR and commercial RuO2 for OER. The superior bifunctional oxygen catalytic activity is mainly attributed to the vital balance between the degree of graphitization and defect engineering, which is proposed to enhance the electron transfer efficiency and conductivity. This work provides more opportunities for understanding and designing other porous graphitized carbon-based electrocatalysts.