Nitrogen Incorporation in TiO₂: Does It Make a Visible Light Photo-Active Material?

Table 1

Nitrogen-1s-binding energies in nitrogen substituted TiO₂.

S. No	Nitrogen-1s-binding energy in N-TiO2 in eV	Assigned to species like	Reference
1	~397	T–N bonding IBAD	[12]
2	396, 400	Ti–N bond chemisorbed dinitrogen	[13]
3	396.2, 398.3, 400.4	Chemically bound, O–Ti–N, chemisorbed N2	[47]
4	396.7, 398.5	N–Ti bonding; symmetric to asymmetric with % N2	[15]
5	398.6, 401	N substituted for oxide, Ti–N–O, incorporated nitrogen	[48]
6	395.4, 400.5	Ti–O–N unreacted NH3, adsorbed nitrogen	[49]
7	396, 400	Ti–N, adventitious N2	[14]
8	396.5, 402	B–N (bonded to Ti) and molecular N2	[50]
9	397.4 −403.7, 401.3, 396	O–Ti–N, chemically bound N	[44]
10	396, 400, 402	N^− species, chemisorbed N2	[6]
11	396	Chemically bound N^−	[51]
12	397	Ti–N concentration dependent	[52]
13	396, 400	O–Ti–N, (TiO2−𝑥N𝑥)
14	398.2	Covalency of Ti–N bond, anionic N, N–Ti–O	[45]
15	396	β-N	[39]
16	396.7, 399.6	Bulk N in two states nitride species N2-anions NHx species chemically bound to H	[41]
17	398.7, 400.1	C–N bonds, hyponitrite, O–Ti–N, C–Ti–O, Ti–O–N–C	[53]
18	396, 399.9	N^− substituted, chemisorbed N2	[30]
19	396.8	β-N, substitution	[54]
20	397, 400, 403	Ti–N, chemisorbed N2	[55]
21	396.2, 400.2	β-N and γ-N	[56]
22	396, 400	Incorporated, trapped N2	[27]
23	395.6, 399.6	N^3− in TiN, Ti–N–O, Ti–O–N	[11]
24	396, 400	O–Ti–N	[57]
25	396, 398.8, 400.5	Substitution, molecular N2	[20]
26	397–402	Substituted nitrogen	[23]
27	397.4, 400.3, 402.5	Ti–N–Ti, Ti–O–N–O/Ti–O–N–N	[58]
28	395.8, 400	β-N, N–O, N–C, N–N	[26]
29	396, 400	β-N, molecular N2	[4]
30	396, 400, 402	β-N, others not assigned	[29]
31	396.1, 402	N–Ti–O, γ-N2	[59]
32	396, 400	β-N, N–O, N–C, N–N	[24]
33	396, 399.5	β-N, chemisorbed N2, interstitial O–N–Ti	[28]
34	396.2, 398.4, 400, 401.5	β-N, chemisorbed nitrogen	[46]
35	396, 400, 402	β-N (396 eV) and molecularly chemisorbed γ-N2 (400 and 402 eV)	[6]
36	399.6, 396	Interstitial nitrogen and substituted nitrogen	[60]
37	400.5	No substitution nitrogen	[61]
38	399	Both substitution and interstitial nitrogen	[62]
39	399.6	Interstitial nitrogen doping at low levels and nitrogen doping at higher levels; the limit for this transition is 1.2 at%.	[63]
40	400	O–Ti–N bonding	[64]
41	399.2, 400.5	C=N–C, N–Csp2, –C=N	[65]
42	400, 402	Chemisorbed nitrogen	[25]
43	399.5	Valence state of nitrogen between −2 and −3	[66]
44	402, 399.5	Chemisorbed molecular nitrogen, interstitial nitrogen	[67]