MOF-derived two-dimensional N-doped carbon nanosheets coupled with Co-Fe-P-Se as efficient bifunctional OER/ORR catalysts.

Abstract

Developing highly efficient, low-cost and bifunctional electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) plays a pivotal role in the scalable applications of zinc-air (Zn-air) batteries. Herein, Co-Fe-P-Se nanoparticles supported on two-dimensional nitrogen-doped carbon (Co-Fe-P-Se/NC) to construct a three-dimensional nanostructure were obtained under the assistance of metal-organic frameworks (MOFs). The two-dimensional nanosheet facilitated the electron transfer rate and exposed abundant active sites. The three-dimensional morphology composed of nanosheets was favorable for electrolyte transport and provided abundant channels for gas diffusion during the catalytic process. Moreover, the coexistence of Co and Fe had important effects on promoting the catalytic performances. Lastly, the catalytic performances for OER and ORR could be promoted effectively after the introduction of selenium and phosphorous in the designed electrocatalyst. Benefiting from the above merits, the prepared Co-Fe-P-Se/NC exhibited excellent catalytic performances for OER (overpotential of 0.27 V at 10 mA cm-2), ORR (half-wave potential of 0.76 V) and rechargeable batteries (a low voltage gap of 0.719 V, high power density of 104 mW cm-2 at 200 mA cm-2 and high energy density of 805 W h KgZn-1). Moreover, the prepared electrocatalyst possessed more stable long-term stability in all the conducted experiments. This work provides a novel approach to develop and construct high-performance bifunctional nanocatalysts for metal-air batteries.