Uniform Bamboo-like N-Doped Carbon Nanotubes Derived from a g-C3N4 Substrate Grown via Anchoring Effect to Boost the Performance of Metal–Air Batteries

Electrocatalysts for oxygen reduction reaction (ORR) are the most critical components in many renewable and sustainable "green" energy storage and conversion technologies, such as metal–air batteries and fuel cells. In this study, bamboo-like N-doped carbon nanotubes derived from a graphitic-like carbon nitride (g-C3N4) substrate containing Fe catalytic species are prepared to achieve enhanced electrocatalytic performance in ORR and high capacity in zinc–air batteries. The aggregation of Fe species at high temperatures in this material is reduced by anchoring them owing to the coordination-effect with N atoms in g-C3N4 groups resulting in the formation of carbon nanotubes with uniform diameters. The walls of bamboo-like nanotubes are made up of structured carbon layers with many voids. X-ray photoelectron spectroscopy reveals the formation of Fe–Nx and pyridine-N/graphite-N surface groups, the latter accounting for 83.3% of the total N species in the optimized sample. The material exhibits superior electrocatalytic performance in primary Zn–air batteries, compared to a state-of-the-art 20 wt % Pt/C catalyst. This study provides a low-cost and efficient pathway for producing N-doped carbon nanotubes for the application of high-performance catalysts in primary Zn–air batteries.