Synthesis of Nitrogen-Doped Carbon Nanocoils with Adjustable Morphology Using Ni—Fe Layered Double Hydroxides as Catalyst Precursors

Tomohiro Iwasaki,Takuma Yoshimura,Masashi Tomisawa,Satoru Watano,Masao Ohyama,Hideya Nakamura,Katsuya Asao

doi:10.5772/60021

Abstract

Nitrogen-doped carbon nanocoils (CNCs) with adjusted morphologies were synthesized in a one-step catalytic chemical vapour deposition (CVD) process using acetonitrile as the carbon and nitrogen source. The nickel iron oxide/nickel oxide nanocomposites, which were derived from nickel–iron layered double hydroxide (LDH) precursors, were employed as catalysts for the synthesis of CNCs. In this method, precursor-to-catalyst transformation, catalyst activation, formation of CNCs, and nitrogen doping were all performed in situ in a single process. The morphology (coil diameter, coil pitch, and fibre diameter) and nitrogen content of the synthesized CNCs was individually adjusted by modulation of the catalyst composition and CVD reaction temperature, respectively. The adjustable ranges of the coil diameter, coil pitch, fibre diameter, and nitrogen content were confirmed to be approximately 500±100 nm, 600±100 nm, 100±20 nm, and 1.1±0.3 atom%, respectively.

Highlights

The morphology and nitrogen content of the synthesized CNCs was indi‐ vidually adjusted by modulation of the catalyst composi‐ tion and chemical vapour deposition (CVD) reaction temperature, respectively
Carbon nanocoils (CNCs) [1,2], which are known as helical carbon nanotubes (HCNTs) or coiled carbon nanofibres, have attracted much attention due to their interesting physicochemical properties that originate from their unique three-dimensional structure
Using a one-step chemical vapour deposition (CCVD) process employing Ni–Fe layered double hydroxide (LDH) and acetonitrile as a catalyst precursor and carbon/nitrogen source, respectively, we demonstrated adjustment of the morphology and nitrogen content of N-doped CNCs

Summary

Introduction

Carbon nanocoils (CNCs) [1,2], which are known as helical carbon nanotubes (HCNTs) or coiled carbon nanofibres, have attracted much attention due to their interesting physicochemical properties that originate from their unique three-dimensional structure. Modulation and enhancement of CNC optical [26], electrical [27], and electrochemical properties [28] has been achieved through nitrogen doping This resulting combination of good performance and versatile functionality of N-doped CNCs renders these materials as promising candidates for use in a range of applications. The control of their morphologies may be important in ensuring the high performance of N-doped CNCs-incorporated products. The current study investigates the effect of catalyst composition (Ni/Fe molar ratio) and CVD reaction temperature on the resulting morphology of Ndoped CNCs

Synthesis of Ni–Fe LDHs

Synthesis of CNCs

Results and discussion

Conclusions