3. Results and discussion
3.1. Characteristics of investigated N-doped TiO
2
Molecular structures of three investigated dopants are shown in
Fig. 1. Urea has a carbonyl group flanked by two primary amines.
DEA is a secondary amine with a dialcohol. TEN has three alkyl
branches and is considered a tertiary amine. These differences in
the basic character of the dopant caused significantly different characteristics
and properties of each N-doped TiO
2
as described below.