N/P-Codoped Carbon Nanotubes for Efficient Oxygen Reduction Reaction

Carbon materials doped with heteroatoms are considered as an optimal substitute for commercial Pt/C (JM-Pt/C) catalysts in oxygen reduction reactions (ORRs) owing to their cost-effectiveness and elevated efficacy. This paper reported a facile single-step approach for the synthesis of N/P-codoped carbon nanotubes (N/P-CNTs) using diammonium dihydrogen phosphate and 2-methylimidazole as precursors and carbon nanotubes (CNTs) as matrix materials. N/P-CNT-900 exhibited exceptional catalytic activity for ORR in alkaline environments with half-wave potential (E1/2) of 0.83 V and showed commendable methanol tolerance and stability. In addition, the catalysts were used to construct a Zn–air battery (ZAB), and its open circuit voltage (OCV) and peak power density (1.56 V, 193.22 mW cm–2) surpassed the performance of JM-Pt/C catalysts (1.50 V, 96.04 mW cm–2), indicating their great advantage for extensive-scale utilization in electrochemical energy conversion devices. This work provided ideas for the development and optimization of metal-free ORR catalysts.