Synergistic coupling of Co4N/VN confined in N-doped carbon derived from zeolitic imidazolate frameworks for oxygen reduction reaction

A novel nanocomposite (Co-V-N/NC) constituted of cobalt-vanadium nitride (Co-V-N) confined in nitrogen-doped porous carbon (NC) is synthesized and studied as a catalyst for the electrochemical oxygen reduction reaction (ORR). In order to optimize catalytic performance, the intrinsic electronic structure is adjusted by constructing the efficient interface coupling of Co4N/VN in composite. Owing to the strong synergistic coupling effect, the optimized Co-V-N/NC catalyst exhibited the best ORR performance with a limiting current density of 6.1 mA cm(-2), and the onset and half-wave potentials of 0.98 and 0.85 V, respectively. The results suggest that the excellent ORR activity of Co-V-N/NC is mainly associated with: (i) effective charge transfer and mass transport between CNN, VN and NC, (ii) a large number of active sites at the phase boundaries, and (iii) improved electrical conductivity due to incorporated metallic Co4N. Also, Co-V-N/NC catalyst is more durable and methanol-resistant compared to the commercial Pt/C catalyst. Density functional theory suggests the importance of synergistic coupling with Co4N/VN to boost the ORR performance. These results indicate its prospects as efficient, cost-effective and robust catalyst for ORR in alkaline media, which is highly desired for fuel cell applications. (C) 2019 Elsevier Ltd. All rights reserved.