Development of highly active and durable non-precious metal bi-functional electrocatalyst for both oxygen reduction and evolution reaction (ORR and OER) remains a significant challenge. Herein, porous mixed spinel MnCo_xO₄ was loaded on the N-doped multi-walled carbon nanotubes (MnCo_xO₄/NCNT) through a facile one-pot hydrothermal method to work as a bi-functional oxygen electrocatalyst. Physical characterizations confirm that the MnCo_xO₄ nanoparticles are composed of mixed spinel-type Co₂MnO₄ and (Co, Mn)[Mn, Co]₂O₄ with a diameter of 5–10 nm, which are dispersed on NCNT with secondary aggregation and resultant porous structure. Electrochemical measurements show that the MnCo_xO₄/NCNT catalyst exhibits high ORR catalytic activity with a dominant four-electron ORR catalytic pathway, remarkable durability, excellent methanol-tolerance, as well as superior OER catalytic activity with significantly decreased overpotential of 0.479 V in alkaline media. The multiple valence states of Co and Mn ions in MnCo_xO₄ coupled with the enlarged specific surface area with the help of NCNT exert crucial roles for the superior catalytic performance for both ORR and OER. Such a bi-functional oxygen electrocatalyst based on mixed spinel MnCo_xO₄ provides a new direction for developing low-cost, highly efficient, and robust multiple valence states transition metal-based electrocatalysts for oxygen electrode.

开发用于氧还原和析出反应（ORR和OER）的高活性和耐用的非贵金属双功能电催化剂仍然是一项重大挑战。在此，通过简便的一锅水热法将多孔的混合尖晶石MnCo _x O ₄负载在N掺杂的多壁碳纳米管（MnCo _x O ₄ / NCNT）上，以用作双功能氧电催化剂。物理特征证实了MnCo _x O ₄纳米颗粒由尖晶石型Co ₂ MnO ₄和（Co，Mn）[Mn，Co] ₂ O _{4混合而成。}直径为5-10 nm，分散在NCNT上，具有二次聚集和最终的多孔结构。电化学测量表明，MnCo _x O ₄ / NCNT催化剂具有较高的ORR催化活性和主要的四电子ORR催化路径，出色的耐久性，优异的耐甲醇性以及优异的OER催化活性，且在0.479 V的超电势下显着降低。碱性介质。MnCo _x O ₄中Co和Mn离子的多价态以及借助NCNT扩大的比表面积，对于ORR和OER的优异催化性能起着至关重要的作用。这种基于混合尖晶石MnCo _x的双功能氧电催化剂O ₄为开发低成本，高效且坚固的多价态过渡金属基氧电极电催化剂提供了新的方向。