Effects of acid on the microstructures and properties of three-dimensional TiO2 hierarchical structures by solvothermal method

Table 1 Morphology, BET surface area, and rate constant of products synthesized with various acid conditions

Acid condition	Unit morphology^a	Size^b(nm)	BET surface area (m²·g⁻¹)	Rate constantk(min⁻¹)
0.68 M HCl	NR	13.5 ± 1.4	40.3	0.135
0.90 M HCl	NR	15.1 ± 1.3	38.1	0.095
1.12 M HCl	NR	17.8 ± 1.7	28.2	0.083
1.35 M HCl	NR	19.8 ± 1.8	18.7	0.074
0.90 M HNO₃	NP	5.0 ± 0.5	190.9	0.104
0.90 M HAc	NP	8.2 ± 0.9	153.7	0.091

^aThe morphology of the unit in the hierarchical structure where NR and NP refer to nanorod and nanoparticle, respectively; ^bthe average diameter of the nanorods or nanoparticles estimated from the FESEM and TEM images.