In‐liquid plasma synthesis of iron–nitrogen‐doped carbon nanoflakes with high catalytic activity

Abstract

AbstractFlake‐shaped carbon nanomaterials with nitrogen (N) and iron (Fe) addition, so‐called carbon nanoflakes (CNFLs), were synthesized by the in‐liquid plasma using two different kinds of additive agents, such as hemin and iron (II) phthalocyanine (FePc). According to scanning electron microscopy images and Raman spectra, CNFLs with a size of at least 100 nm order were formed regardless of types of additive agents, and crystallinity of six‐membered ring structures was improved as additive agents increased. Photoelectron spectra showed that pyridinic N contents increased from 1.05% to 2.02% with increasing FePc, while those decreased from 0.34% to 0.14% with hemin. In the oxygen reduction reaction, onset potential values also increased from 0.71 to 0.79 eV with increasing FePc, while those decreased from 0.60 to 0.47 eV with hemin. These results suggested that the catalytic activity of CNFLs was effectively improved by the increase of pyridinic N by the in‐liquid plasma synthesis with FePc. In contrast, the electron transfer numbers reached 3.81 when hemin increased, although those were less than 2.88 in the cases using FePc. These results mean that the in‐liquid plasma synthesis method of CNFLs using FePc has the potential to further improve its catalytic activity.