Petal-like N, O-codoped carbon nanosheets as Mott–Schottky nanoreactors in electrodes of Zn-Air batteries and supercapacitors

Abstract

Heteroatoms-doped carbon nanosheets showed excellent electrocatalytic activity in oxygen reduction reaction (ORR). Herein, monoatomic Fe–N–C sites anchored on petal-like N, O-codoped carbon nanosheets surface were prepared using hemin chloride and were selected as Mott-Schottky nanoreactors in electrodes of Zn-air batteries and supercapacitors. Electron transport and mass transfer at the heterojunction interface between the nanosheets and Fe–N–C active sites were investigated thoroughly. Results indicated that not only petal-like nanosheets with abundant mesopores and high specific surface area could provide fast electrolytes diffusion path, but also the monoatomic Fe–N–C as Mott–Schottky nanoreactors was conducive to the electron transfer. The NGA-900@HC towards ORR under alkaline conditions showed a half-wave (E1/2) and onset potential (Eonset) of 0.85 and 1.16 V, respectively, which were better than those of Pt/C catalyst (vs. RHE) under a kinetic current density (JK) of 58.7 mA cm−2 at 0.55 V with the rotation rate of 1600 rpm and a limiting current density (JL) of 5.5 mA cm−2. This work provided an in-depth understanding of the correlation between ORR activity and work functions of doped mesoporous carbon materials.