The search for new ways to make inexpensive and efficient electrocatalysts to replace precious-metal platinum catalysts for oxygen reduction and water splitting is still a great challenge. Here, we report a facile and effective strategy for the rational design and construction of three-dimensional (3D) architectures for superior electrocatalysis through the integration of one-dimensional (1D) electrospun carbon nanofibers (CNFs), 1D carbon nanotubes (CNTs) and 0D oxygen-deficient Mn3Co7–Co2Mn3O8 nanoparticles (NPs). The rationale behind the marriage and integration of nanostructures with different dimensions presented in this work is that during heat treatment, the in situ-produced CoMnO NPs are partly reduced to Co2Mn3O8 by a carbon precursor with an amount of metallic Mn3Co7 formed at the interface between the Co2Mn3O8 NPs and carbon, which can act as the catalysts for the growth of 3D CNT forests. The 3D CoMnO@CNT/CNF architectures exhibit superior electrocatalytic activity and stability for the oxygen reduction, oxygen evolution and hydrogen evolution reactions. The remarkable electrochemical properties are mainly attributed to the synergistic effects from the engineering of oxygen-deficient binary CoMn oxide NPs with exposed active sites and 3D hierarchical porous structures consisting of branched CNTs and interconnected CNFs. The present work demonstrates the first example of integrating multiple active catalytic centers onto/into 3D architectures for developing highly efficient non-precious metal nanocatalysts for electrochemical energy devices.
