Aligned CNx nanotubes by pyrolysis of ferrocene/C60 under NH3 atmosphere

TLDR

Aligned CNx (x < 0.1) nanotubes were produced by pyrolyzing ferrocene/C60 mixtures at 1050 °C in an ammonia atmosphere, and their structure and composition were characterized by high‑resolution TEM and electron energy‑loss spectroscopy. The resulting CNx nanotubes (15–70 nm diameter, <50 µm length) grow in large (<3 mm²) bamboo‑like flakes with fewer than 15 graphitic layers, display high nitrogen concentrations in curved domains, retain a double‑peak σ* N‑K edge indicating no transition to a fullerene‑like phase, and demonstrate that ammonia‑derived nitrogen incorporation yields more efficient substitution than solid precursors.

Abstract

Aligned CNx (x&amp;lt;0.1) nanotubes have been generated by pyrolyzing ferrocene/C60 mixtures at 1050 °C in an ammonia atmosphere. The structure and composition of the product were determined by high-resolution transmission electron microscopy and high spatial resolution electron energy-loss spectroscopy. The CNx tubes (15–70 nm diameter, &amp;lt;50 μm length) grown in large flakes (&amp;lt;3 mm2) consist of a reduced number of “graphitic” layers (&amp;lt;15 on either side) arranged in a bamboo-like structure. Areas of high nitrogen concentration were found within curved or corrugated “graphite-like” domains. The observation of a well-developed double peak in the σ* feature of the N K-edge suggests that the material has not undergone the transition to the fullerene-like phase known for nitrogenated carbons. Incorporation of nitrogen from the gas phase (NH3) into CNx nanotubes therefore leads to improved and more efficient N substitution into the network as compared to the synthesis with solid nitrogen-containing precursors reported earlier.