The Synergistic Effect of Nitrogen Dopant and Calcination Temperature on the Visible-Light-Induced Photoactivity of N-Doped TiO₂

Table 1

Characteristics for N-TiO₂ at various ammonia/TTIP molar ratios under different calcination temperatures.

Sample^a	XRD				BET	TG-DTA	TEM	Optical properties
	Phase ratio		Crystallite size		Surface area (m^2/g)	A^b→R^c Temp. (°C)	Size; (nm)	𝜆𝑔,1	𝐸𝑔,1	𝜆𝑔,2	𝐸𝑔,2
	A^b%	R^c%	A^b (nm)	R^c (nm)				(nm)	(nm)	(nm)	(nm)
A00T4	90	10	32	—	93	703	11 ± 1	392	3.16	—	—
A05T4	89	11	28	—	108	710	12 ± 1	392	3.16	505	2.46
A10T4	90	10	28	—	119	720	12 ± 1	391	3.17	506	2.45
A15T4	87	13	29	—	119	728	11 ± 1	388	3.20	513	2.42
A20T4	90	10	32	—	98	730	12 ± 1	390	3.18	510	2.43
A25T4	90	10	37	—	98	728	12 ± 1	392	3.16	515	2.41
A30T4	92	8	37	—	86	729	12 ± 1	392	3.16	514	2.41
A00T5	94	6	46	—	50	703	13 ± 2	402	3.08	—	—
A05T5	89	11	46	98	64	710	13 ± 1	404	3.07	503	2.47
A10T5	90	10	41	87	68	720	15 ± 2	400	3.10	508	2.44
A15T5	91	9	40	—	71	728	15 ± 2	396	3.13	517	2.40
A20T5	94	6	45	—	62	730	15 ± 2	394	3.15	513	2.42
A25T5	94	6	49	—	55	728	17 ± 2	397	3.12	507	2.45
A30T5	94	6	47	—	53	729	17 ± 2	397	3.12	510	2.43
A00T6	34	66	106	156	7	703	24 ± 2	420	2.95	—	—
A05T6	14	86	86	128	8	710	40 ± 3	422	2.94	—	—
A10T6	14	86	81	132	9	720	40 ± 4	425	2.92	—	—
A15T6	22	78	79	141	14	728	35 ± 3	424	2.92	—	—
A20T6	60	40	85	184	17	730	34 ± 3	415	2.99	—	—
A25T6	78	22	90	184	16	728	35 ± 4	416	2.98	—	—
A30T6	74	26	97	169	12	729	36 ± 4	415	2.99	—	—
A00T7	6	94	131	177	2	703	80 ± 5	424	2.92	—	—
A05T7	3	97	95	148	5	710	145 ± 10	428	2.90	—	—
A10T7	3	97	102	149	6	720	145 ± 10	429	2.89	—	—
A15T7	3	97	92	159	6	728	150 ± 11	428	2.90	—	—
A20T7	6	94	103	163	4	730	170 ± 13	428	2.90	—	—
A25T7	15	85	108	178	8	728	60 ± 6	426	2.91	—	—
A30T7	15	85	117	182	6	729	60 ± 6	427	2.90	—	—
A00T8	1	99	—	174	3	703	200 ± 17	424	2.92	—	—
A05T8	1	99	—	161	3	710	190 ± 15	428	2.90	—	—
A10T8	1	99	—	159	3	720	160 ± 13	429	2.89	—	—
A15T8	1	99	—	171	3	728	170 ± 15	428	2.90	—	—
A20T8	1	99	—	164	2	730	160 ± 14	428	2.90	—	—
A25T8	3	97	106	184	4	728	200 ± 18	427	2.90	—	—
A30T8	3	97	127	179	3	729	170 ± 15	429	2.89	—	—

^aAXXTY: ammonia/TTIP molar ratio = 0.XX; calcination temperature = Y00°C.
^bAnatase.
^cRutile.