Fe7C3 nanoparticles with in situ grown CNT on nitrogen doped hollow carbon cube with greatly enhanced conductivity and ORR performance for alkaline fuel cell

Abstract Reasonable design of the porous metal-organic frameworks (MOFs) to convert a burgeoning carbon-based catalysts with high oxygen reduction reaction (ORR) activity are still challenging in energy conversion, storage and transport. Herein, Fe7C3-doped in-situ grown carbon nanotubes and N-doped hollow carbon (Fex-CNT@NHC) are prepared by using a simple and robust preparation method, which is used cubic ZIF-8-derived zinc oxide cubes as a template for secondary MOFs re-growth followed by the final carbonization. In the 0.1 M KOH, the as-pyrolyzed Fe0.1-CNT@NHC electrocatalyst displays the value of half-wave potential is 0.92 V and the value of diffusion-limited current density is 6.08 mA cm−2, respectively, which are close to the corresponding electrochemical values of the standard commercial Pt/C (0.89 V and 5.89 mA cm−2). Meanwhile, the material has passed relevant tests on its long-term stability and methanol tolerance in alkaline media, showing that it has excellent ORR activity and efficient stability under electrocatalysis. Furthermore, the Fe0.1-CNT@NHC materials catalyze a Zn-air battery that delivers a performed peak power density of 105.9 mW cm−2. The impressive catalytic activity of Fe0.1-CNT@NHC stems from the effective synergy between efficient Fe and N co-doping, large specific surface area, and high electrical conductivity. This preparation route for carbon nanomaterials will provide a new synthetic strategy to synthesize high-performance non-noble metal carbon-based ORR catalysts for practical energy-related applications.