Nitrogen and Phosphorus-codoped Carbon Nanotube/Fe2P Nanoparticle Hybrids Toward Efficient Oxygen Reduction and Zinc-air Batteries

Abstract

Incorporating metal compound nanoparticles in carbonaceous matrix is a valid strategy to fabricate highly efficient oxygen reduction electrocatalysts. Herein, N, P-codoped carbon nanotubes embedded with Fe2P nanoparticles (Fe2P/NPCt) were synthesized in this work. Results show carbon nanotubes have a large specific surface area (987 m2 g−1) with an inner diameter of ∼60 nm. About 5.90 wt% nitrogen (35.18% pyridinic N) and 2.56 wt% phosphorus (mainly in the form of P–C and P–Fe) was doped in Fe2P/NPCt. HRTEM and XRD results confirmed the well dispersed Fe2P nanoparticles in 5 ∼10 nm on carbon nanotubes. The electrochemical performance of Fe2P/NPCt was evaluated in 0.10 M KOH using cyclic voltammetry, linear scanning voltammetry, and chronoamperometry. Fe2P/NPCt exhibits high electrocatalytic activity towards oxygen reduction with an onset potential of 1.029 V (vs RHE) and a limited current density of 6.79 mA cm−2, surpassing those of 20% Pt/C (0.950 V and 5.20 mA cm−2). Furthermore, Fe2P/NPCt presents outstanding durability and good methanol tolerance during long-term ORR. When assembled in a primary zinc-air battery (ZAB), the maximum power density and specific capacity of ZAB reach 175.48 mW cm−2 and 744.1 mAh g−1, respectively, outperforming ZAB equipped with 20% Pt/C.