Table 1.

Literature overview of representative synthetic pathways toward N-CNTs.

method	C/N feedstock	catalyst (precursor)	T, °C	product	N content, wt %	ref.
arc discharge	graphite, melamine	Ni–Y	—	N-SWCNT	1.0	[27]
arc discharge	graphite, N2	Fe–Ni–Co	—	N-CNT	4.6–13.7	[28]
arc discharge	graphite, N2	Fe2O3, Co2O3, NiO	—	N-CNT	unknown	[29]
high-pressure CO conversion (HiPCO)	graphite, N2	-	1300	N-CNT, nanofibers	3.0–13.0	[30]
c-CVD	CH3CN	Co–Mo/MgO	700	bamboo-like N-CNT	12.0	[31]
c-CVD	CH3CN CH3CN + H2	Fe–MgO	850	bamboo-like N-CNT bamboo-like N-CNT	0.94 2.62	[32]
c-CVD	ethylenediamine	Co, FeCp2	780 860 980 1080	irregular N-CNT pearl-like nanobells bamboo-like N-CNT bamboo-like N-CNT	24.45 22.42 19.56 18.77	[33]
c-CVD	NH3	iron(II) phthalate, SiO2	850	aligned bamboo-like N-CNT	9.0	[34]
c-CVD	C2H2, NH3	Fe(CO)5	750 850 950	bamboo-like N-CNT	2.8 4.2 6.6	[35]
c-CVD	CH3CN	Co–Ni/SiO2	800	twisted bundles N-MWNT	3.0	[36]
c-CVD	THF, CH3CN	Fe(acac)3	950	bamboo-like N-MWNT	16.0–20.0	[37]
c-CVD	1. propylene, 2. CH3CN 1. CH3CN, 2. propylene	Al2O3	800	aligned N-CNT	3.2 3.5	[38]
c-CVD	C2H2, NH3	Fe/SiO2	850	bamboo-like N-CNT	0.4–2.4	[39]
c-CVD	CH4, NH3 C2H2, NH3	Fe/Si	900 1000 1100	bamboo-like N-CNT	2.0–6.0	[40]
c-CVD	CH3CN	Al2O3	800	aligned N-CNTs within Al2O3 pores	unknown	[41]
c-CVD	pyridine pyrimidine	FeCp2	600–900	aligned bamboo-like N-CNT	1.0–2.0 3.2	[42]
c-CVD	CH4, NH3, N2	Ni–Fe	720–810	bamboo-like CNT with graphene sheets	0–4	[43]
bias CVD	CH4, N2	Fe–Ni	500	bamboo-like N-CNT	≈15	[44]
plasma CVD	CH4, NH3	SiO2/Si	450	N-SWCNT	0–4	[45]
plasma CVD	graphite, N2	Ni	650	aligned bamboo-like N-CNT	20.0–30.0	[46]
magnetron sputtering	SWNTs, N2+	—	—	→ N-SWCNT → amorphous	450 ppm	[25]
low-energy ion irradiation	MWNTs, N2+	—	—	N-MWCNTs	0.58	[47]