PPy-derived N, P co-doped hollow carbon fiber decorated with island-like Ni2P nanoparticles as bifunctional oxygen electrocatalysts

Abstract Constructing high efficient and robust bifunctional electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for energy conversion and storage electrochemical system. Herein, an efficient bifunctional ORR/OER electrocatalyst of N, P co-doped hollow carbon fiber decorated with island-like Ni2P nanoparticles (Ni2P@HCF-900) is reported with PPy template. The unique fiber morphology and hollow structure, which not only facilitates the penetration-transmission of O2 and electrolyte, but also exposes more active sites, moreover, the synergistic effect between Ni2P and N, P co-doped carbon is also obtained to benefit bifunctional oxygen catalytic activities. In 0.1 M alkaline KOH solution, Ni2P@HCF-900 delivers a promising half-wave potential of 0.803 V and a quasi-four electron pathway for ORR, a low overpotential of 366 mV at 10 mA cm−2 for OER. The work provides a strategy to enhance bifunctional oxygen catalytic performance by designing of morphology and structure.