Nitrogen-doped carbon materials with vacancies/defects have been developed as highly efficient ORR electrocatalysts but with poor activity for OER, which limits their application in rechargeable metal-air batteries. Filling the vacancies/defects with heteroatoms is expected to be an effective strategy to obtain surprising catalytic activities and improve their stability especially under the strongly oxidizing conditions during the OER process. Herein, we successfully transformed the defect-rich 3D carbon nanosheets (DCN) into a bifunctional ORR/OER electrocatalyst (DCN-M) by utilizing the in-situ generated vacancies to capture metal cations via a modified salt-sealed strategy. By varying the metal (Fe, Ni) content, the captured metal cations in DCN-M existed in different chemical states, i.e., metal atoms were stabilized by C−N bonds at low metal contents, while at high metal contents, bimetal particles were covered by graphene layers, taking responsibility for catalyzing the ORR and OER, respectively. In addition, the in-situ formed graphene layers with an interconnected structure facilitate the electron transport during the reactions. The Janus-feature of DCN-M in structures ensures superior bifunctional activity and good stability towards ORR/OER for the rechargeable Zn-air battery. This work provides an effective strategy to design multifunctional electrocatalysts by heteroatom filling into vacancies of carbon materials.

具有空位/缺陷的掺氮碳材料已被开发为高效的ORR电催化剂，但对OER的活性却很差，这限制了它们在可充电金属空气电池中的应用。期望用杂原子填充空位/缺陷是获得令人惊奇的催化活性并改善其稳定性的有效策略，尤其是在OER过程中的强氧化条件下。在这里，我们通过利用改进的盐封策略利用原位产生的空位来捕获金属阳离子，成功地将富含缺陷的3D碳纳米片（DCN）转变为双功能ORR / OER电催化剂（DCN-M）。通过改变金属（Fe，Ni）的含量，DCN-M中捕获的金属阳离子以不同的化学状态存在，即 在低金属含量下，金属原子通过C-N键稳定，而在高金属含量下，双金属颗粒被石墨烯层覆盖，分别负责催化ORR和OER。另外，具有互连结构的原位形成的石墨烯层促进了反应期间的电子传输。DCN-M在结构中的Janus功能可确保出色的双功能活性和可充电Zn-空气电池对ORR / OER的良好稳定性。这项工作提供了一种通过杂原子填充碳材料空位来设计多功能电催化剂的有效策略。具有互连结构的原位形成的石墨烯层有助于反应期间的电子传输。DCN-M在结构中的Janus功能可确保出色的双功能活性和可充电Zn-空气电池对ORR / OER的良好稳定性。这项工作提供了一种通过杂原子填充碳材料空位来设计多功能电催化剂的有效策略。具有互连结构的原位形成的石墨烯层有助于反应期间的电子传输。DCN-M在结构中的Janus功能可确保出色的双功能活性和可充电Zn-空气电池对ORR / OER的良好稳定性。这项工作提供了一种通过杂原子填充碳材料空位来设计多功能电催化剂的有效策略。