Ion implantation technique was employed to introduce iron nanoparticles (Fe NPs) into a carbon precursor polymer with the aim of forming of a graphitic nanostructure through catalytic graphitization by the introduced Fe NPs. A phenolic resin was implanted by 100 keV Fe⁺ ions with ion fluence of 1 × 10¹⁴–1 × 10¹⁶ ions/cm² at ambient temperature under vacuum, and subsequently heat-treated at 800 °C in a nitrogen gas atmosphere. It was found that the particle size of Fe NPs could be controlled in the range of 5–30 nm by the Fe⁺ ion fluence. Additionally, it was found that a nanosized turbostratic graphite structure with mean interlayer distance of 0.3531 nm, which is consisted of shell-like carbon layers and intricately distorted carbon layers, was formed around the Fe NPs. The ion implantation technique is one of the advantageous ways to introduce size-controlled fine metal NPs which are effective for the formation of graphitic nanostructure from a carbon precursor polymer.

A novel process for fabricating a nitrogen-doped carbon catalyst from a precursor polymer utilizing the high-energy electron beam (EB) irradiation technique was examined with the aim of simultaneously forming a graphitic nanostructure and nitrogen doping in thermally non-equilibrium conditions. A blend of phenolic resin and cobalt chloride was irradiated by a 2 MeV EB under flowing ammonia gas and heated up to 800 °C. It was found that the EB irradiation produces carbon material with a high content of the graphite phase and enhances the amount of N-doping, especially pyridinic-N, compared with the common heat treatment in an electric furnace. The obtained carbon material exhibited catalytic activity for oxygen reduction reaction (ORR) with an ORR potential of 0.7 V versus RHE and an electron transfer number of 3 in 0.5 M H ₂ SO ₄ .