Co2P@N,P-Codoped Carbon Nanofiber as a Free-Standing Air Electrode for Zn–Air Batteries: Synergy Effects of CoNx Satellite Shells

Here, a free-standing electrode composed of cobalt phosphides (Co2P) supported by cobalt nitride moieties (CoNx) and an N,P-codoped porous carbon nanofiber (CNF) in one-step electrospinning of environmentally friendly benign phosphorous precursors is reported. Physiochemical characterization revealed the symbiotic relationship between a Co2P crystal and surrounding nanometer-sized CoNx moieties embedded in an N,P-codoped porous carbon matrix. Co2P@CNF shows high oxygen reduction reaction and oxygen evolution reaction performance owing to the synergistic effect of Co2P nanocrystals and the neighboring CoNx moieties, which have the optimum binding strength of reactants and facilitate the mass transfer. The free-standing Co2P@CNF air-cathode-based Zn–air batteries deliver a power density of 121 mW cm–2 at a voltage of 0.76 V. The overall overpotential of Co2P@CNF-based Zn–air batteries can be significantly reduced, with low discharge–charge voltage gap (0.81 V at 10 mA cm–2) and high cycling stability, which...