Vanadium Nitride Supported on N-Doped Carbon as High-Performance ORR Catalysts for Zn-Air Batteries

It is desirable to prepare low-cost non-noble metal catalysts using a simple and efficient method. Herein, we display for the first time that nitrogen-doped hierarchical porous carbon-supported vanadium nitride (VN/NC/C-x) catalysts can be regulated by dicyandiamide (DCDA). The introduction of DCDA not only effectively controls the pore structure, but also plays an important role in adjusting oxygen vacancies and d-electrons. In addition, DCDA is not only a significant raw material for the N-doped carbon, but also a nitrogen source for the preparation of vanadium nitride. The VN/NC/C-3 catalyst was prepared after optimization of the preparation parameters, and the macro/micro structure demonstrates a superior ORR performance in alkaline media with a positive onset potential of 0.85 V and a half-wave potential of 0.75 V, the limiting current density is as high as 4.52 mA center dot cm(-2), and the Tafel slope is only 75.54 mV center dot dec(-1). The VN/NC/C-3-based Zn-air battery exhibits a highest peak power density (161.82 mW center dot cm(-2)) and an excellent energy density (702.28 mAh center dot kg(Zn)(-1) and 861.51 Wh center dot kg(Zn)(-1)). This work provides a valuable synthetic approach for the preparation of other transition metal nitride catalysts with a relative economic value and high performance.