Co encapsulated in N-doped carbon nanotubes (Co-NCNT) catalysts are of high interest as bifunctional electrocatalyst material for both efficient oxygen evolution and reduction (OER/ORR) in applications of rechargeable metal-air batteries. Up to now, the role played by the functional metal species in OER/ORR is still insufficiently understood. The main focus of our research is to shed light on the mechanistic role of the Co species that serve as active sites in the bi-functional Co-NCNT catalysts. It is found that S700 exhibits an outstanding OER/ORR activity. We thus hypothesize that Co^II and Co^III clusters predominately function as active sites in the OER and ORR processes, respectively. Furthermore, OER/ORR activity for Co-NCNT catalyst primarily correlates to e_g occupation. A near-unity occupancy of the e_g orbital of S700 is revealed to be the cause for the maximum intrinsic OER/ORR activity, which provides guidelines for the design of highly active catalysts.

包封在N掺杂碳纳米管（Co-NCNT）催化剂中的Co作为双功能电催化剂材料备受关注，可用于可充电金属空气电池的高效氧释放和还原（OER / ORR）。迄今为止，对功能金属在OER / ORR中所起的作用仍知之甚少。我们研究的主要重点是阐明作为双功能Co-NCNT催化剂中活性位点的Co物种的机械作用。发现S700表现出杰出的OER / ORR活性。因此，我们假设Co ^II和Co ^III簇分别在OER和ORR过程中主要充当活性位点。此外，OER / ORR用于共NCNT催化剂活性主要关联到E_克占用。电子的近团结占用_克轨道S700的显露是为最大固有OER / ORR活性，它提供了准则高活性催化剂的设计的原因。