Table 2.

XPS measurements of the carbon 1s and nitrogen 1s lines for various nitrogen-doped graphitic carbon nanomaterials reported in the literature. The columns show the material, diameter of the nanostructure, the carbon 1s energy assigned to C–C bonds, and to C–N bonds, the nitrogen 1s energies assigned to pyridinic (pnic), pyrrolic (plic) and substitutional (subs) nitrogen, the concentration of nitrogen in atomic percent, and the citation for each measurement.

		C 1s (eV)		N 1s (eV)
material	d (nm)	C–C	C–Na	pnic	plic	subs	N atomic %	references
(C59N)2	0.71	285.2	—	—	—	400.72	1.6	[132]
SW	1–1.6	284.5	—	398.5	—	400.6	0.3	[119]
SW	<2	284.8	286.3, 288.3	399.8	—	401.8	3	[121]
SW	1–1.8	284.7b	287	397.9	—	401.1	2	[120]
SW	1.1–1.2	—	—	398.6	—	400.5	1.1	[133]
SW	0.9–1.8	—	—	397.6	—	400.5	1	[124]
SW	0.8–1.0	284.5	285.8, 287	398.4	400.9	—	3.2	[134]
S/DW	0.8–2	284.5	—	398.6	—	400.6	0.2	[117]
DW	—	284.5	285.5	398.3	—	400.2	3	[135]
DW	1.6–3.2	284.3	—	398.0	—	401.3	1	[136]
FW	1–5	284.5	287	398.6	—	400.88	6	[116]
MW	15–80	284.5	285.5	398.4	—	400.2	8	[137]
MW	10–40	284.7	285.7 ± 0.1	398.5	—	400.8	4	[138]
MW	30–80	284.5	—	398.6	—	400.5	5	[139]
MW	30–60	284.5	—	398.2	—	400.5	25.7	[140]
MW	20–60	284.1	285.9	398.2	400.2	401.1	5.2	[141]
SLG/Cu	∞	284.8	285.8, 287.5	398.2	400.1	401.7	8.9	[126] c
SLG/Au/Ni(111)d	∞	284.4	—	398.4	400.3	401.3	0.48	[127]
SLG/Cu	∞	284.6	285.8	398.6	—	400.6	0.25	[142]
SLG/SiO2	∞	284.5	—	398.0	398.9	400	0.4	[143] e
FLG	∞	284.6f	—	398.45	399.45	400.92	12.8	[67]
graphite	∞	—	—	398.5	399.9	401.1	2.7	[144]

^aWhen two values are listed, the lower binding energy component has been assigned to sp² C–N and the higher to sp³ C–N bonds. ^bShifted from 284.5 eV upon doping. ^cPredominant presence of graphitic nitrogen subsequently verified by transmission electron microscopy [145–146]. ^dQuasi-freestanding graphene via Au intercalation as in [69–70]. ^eMost values not explicitly reported, estimated from spectrum graph. A slight C 1s downshift and broadening is observed in the doped sample. ^fSynchrotron-based scanning X-ray photoelectron microscopy measurements on ion-implanted few-layer graphene samples. The pristine sample was measured at 284.47 eV.