Co/VN heterojunction anchored on multi-dimensional N-doped carbon for high-performance zinc–air batteries

Thanks to high electroconductivity and excellent electrochemical durability, the vanadium nitride (VN) is gradually developed as an electrocatalyst. However, the oxygen dissociation ability of VN species is usually weak due to the lack of d-orbital electrons in the vanadium. Herein, Co nanoparticles with abundant 3d-orbital electrons were utilized to construct the heterojunction with the VN (Co/VN), which anchored on the multi-dimensional N-doped carbon (CoVN/NC) for oxygen reduction reaction (ORR). The heterogeneous interface within the Co/VN increased more active sites and was conducive to adsorbing more O-containing intermediates. The oxygen dissociation ability of intermediates was improved on the VN surface. Based on “3d-orbital electron complementary effect”, the Co nanoparticles transferred d-orbit electrons to the VN and regulated the electronic configuration of VN components. The continuity of the V 3dz2 orbitals within the Co/VN was enhanced near the Fermi level, which promoted the formation of strong σ bonds between the CoVN/NC and O pz orbitals. Therefore, the O–O bond of O2 was more easily broken on the CoVN/NC surface. The CoVN/NC displayed the half-wave potential of 0.85 V for ORR. The zinc-air battery with the CoVN/NC possessed a power density of 200.7 mW cm−2 and a cycle stability of 180 h. This work would provide a practical reference for improving electrocatalytic activities of VN species.