The nitrogen-doped carbon supported ultra-small vanadium nitride nanoparticles as a highly efficient oxygen reduction electrocatalyst for the rechargeable Zn–air battery

Abstract

• Vanadium-based polyoxometalate modified by [(C 8 H 17 ) 3 NCH 3 ] + has excellent dispersion. • The rapid calcination strategies can reduce the agglomerate of VN nanoparticles. • The size of VN nanoparticles is around 5–10 nm. • VN/NC has excellent ORR activity and stability in zinc–air batteries. The regulating active sites of vanadium nitride (VN)–based materials is an effective way to improve their oxygen reduction reaction (ORR) performance, which is expected to effectively solve the problem of sluggish kinetics in the cathode of Zn–air batteries. However, traditional synthesis methods cannot uniformly disperse VN, cause inadequate exposure to the active site, resulting in poor ORR performance. Herein, we successfully prepared a nitrogen–doped carbon supported ultra-small vanadium nitride nanoparticles (VN/NC) by organic group modification combined with rapid calcination strategies. The size of VN nanoparticles is around 5–10 nm. The smaller size can ultimately improve the ORR performance of VN/NC by exposing more active sites. Finally, the half–wave potential of the VN/NC is 0.813 V for ORR. More importantly, the Zn–air batteries assembled with the VN/NC catalyst as the air cathode shows a high power density (115 mW cm −2 ) and a large specific capacity (673 mAh g −1 ). It indicates that this approach can successfully synthesize ultra-small size VN nanoparticles, which is of great significance to the development of efficient air cathode materials for the Zn–air battery.