is, the final aim is to make g-C 3 N 4 and TiO 2 contact with each other, further forming
a heterojunction structure between g-C 3 N 4 and TiO 2 .
7.2.1 Physically Mixing g-C 3 N 4 and TiO 2
This preparation method refers to firstly synthesizing g-C 3 N 4 and TiO 2 , respectively,
and then physically mixing the two components together by ball milling or evaporation of dispersion solution. Hongjian Yan et al. prepared TiO 2 -C 3 N 4 by mixing
TiO 2 and g-C 3 N 4 powder using a ball milling method with different contents of
g-C 3 N 4 . The TiO 2 was synthesized by the hydrolysis of TiCl 4 in ammonia, and the
g-C 3 N 4 was prepared by directly heating melamine at an atmosphere of Ar
[37]. Yongfa Zhu et al. also fabricated g-C 3 N 4 /TiO 2 hybrid photocatalysts by a
facile ball milling method. In their experiments, g-C 3 N 4 was synthesized by directly
heating melamine, and g-C 3 N 4 /TiO 2 photocatalysts were obtained by mixing
g-C 3 N 4 and TiO 2 powder in a ball mill. Their results showed that a layered structure
of g-C 3 N 4 was formed on the surface of TiO 2 [38]. Interestingly, they found that the
as-prepared catalyst showed highly enhanced photocatalytic performance and the
photocatalytic efficiency increased gradually with the increase of milling rate.
Apart from the ball milling, solvent evaporation is also a commonly used physical
mixing method for the synthesis of g-C 3 N 4 /TiO 2 heterojunction photocatalyst. In
this preparation process, g-C 3 N 4 and TiO 2 are homogeneously dispersed in a solvent
such as methanol, and then the solvent is evaporated to make g-C 3 N 4 and TiO 2
contact with each other and thus form the heterojunction structure. Jingyu Wang
et al. hybridized anatase TiO 2 nanosheets with dominant (001) facets with g-C 3 N 4
via this facile solvent evaporation method. The polymeric g-C 3 N 4 was synthesized
by directly calcinating urea, and the anatase TiO 2 nanosheets with dominant (001)
facets were prepared by a solvothermal reaction of tetrabutyl titanate (TBT). After
the solvothermal treatment, the well-washed precipitate was dispersed into methanol
and mixed with g-C 3 N 4 , followed by sonication for 30 min to completely disperse
the g-C 3 N 4 . After that, the above sample was stirred in a fume hood for 12 h to
evaporate the methanol, and the rest powder was dried at 100
C for 4 h
[39]. Dongjiang Yang et al. synthesized g-C 3 N 4 /TiO 2 (B) nanofibers with exposed
(001) plane with the enhanced visible light photoactivity through a facile solvent
evaporation operation to the methanol solution of g-C 3 N 4 and TiO 2 (B). The g-C 3 N 4
was prepared by directly heating melamine in air at the temperature of 550
C for
4 h, and TiO 2 (B) nanofibers were synthesized using a hydrothermal method
combined with a subsequent calcination treatment [40]. Hong Huang et al. prepared
heterostructured g-C 3 N 4 /Ag/TiO 2 microspheres with improved photocatalytic performance under visible light irradiation. As shown in Fig. 7.1, the protonated g-C 3 N 4
sheets were synthesized by calcinating melamine and followed by the protonation in
HCl solution, and TiO 2 nanomaterial was prepared by a typical hydrothermal
method of Ti(OC 4 H 9 ) 4 , and then Ag/TiO 2 microspheres were obtained by depositing
7.2 The Preparation Methods of g-C 3 N 4 /TiO 2 Heterojunction Catalyst
175
a heterojunction structure between g-C 3 N 4 and TiO 2 .
7.2.1 Physically Mixing g-C 3 N 4 and TiO 2
This preparation method refers to firstly synthesizing g-C 3 N 4 and TiO 2 , respectively,
and then physically mixing the two components together by ball milling or evaporation of dispersion solution. Hongjian Yan et al. prepared TiO 2 -C 3 N 4 by mixing
TiO 2 and g-C 3 N 4 powder using a ball milling method with different contents of
g-C 3 N 4 . The TiO 2 was synthesized by the hydrolysis of TiCl 4 in ammonia, and the
g-C 3 N 4 was prepared by directly heating melamine at an atmosphere of Ar
[37]. Yongfa Zhu et al. also fabricated g-C 3 N 4 /TiO 2 hybrid photocatalysts by a
facile ball milling method. In their experiments, g-C 3 N 4 was synthesized by directly
heating melamine, and g-C 3 N 4 /TiO 2 photocatalysts were obtained by mixing
g-C 3 N 4 and TiO 2 powder in a ball mill. Their results showed that a layered structure
of g-C 3 N 4 was formed on the surface of TiO 2 [38]. Interestingly, they found that the
as-prepared catalyst showed highly enhanced photocatalytic performance and the
photocatalytic efficiency increased gradually with the increase of milling rate.
Apart from the ball milling, solvent evaporation is also a commonly used physical
mixing method for the synthesis of g-C 3 N 4 /TiO 2 heterojunction photocatalyst. In
this preparation process, g-C 3 N 4 and TiO 2 are homogeneously dispersed in a solvent
such as methanol, and then the solvent is evaporated to make g-C 3 N 4 and TiO 2
contact with each other and thus form the heterojunction structure. Jingyu Wang
et al. hybridized anatase TiO 2 nanosheets with dominant (001) facets with g-C 3 N 4
via this facile solvent evaporation method. The polymeric g-C 3 N 4 was synthesized
by directly calcinating urea, and the anatase TiO 2 nanosheets with dominant (001)
facets were prepared by a solvothermal reaction of tetrabutyl titanate (TBT). After
the solvothermal treatment, the well-washed precipitate was dispersed into methanol
and mixed with g-C 3 N 4 , followed by sonication for 30 min to completely disperse
the g-C 3 N 4 . After that, the above sample was stirred in a fume hood for 12 h to
evaporate the methanol, and the rest powder was dried at 100
C for 4 h
[39]. Dongjiang Yang et al. synthesized g-C 3 N 4 /TiO 2 (B) nanofibers with exposed
(001) plane with the enhanced visible light photoactivity through a facile solvent
evaporation operation to the methanol solution of g-C 3 N 4 and TiO 2 (B). The g-C 3 N 4
was prepared by directly heating melamine in air at the temperature of 550
C for
4 h, and TiO 2 (B) nanofibers were synthesized using a hydrothermal method
combined with a subsequent calcination treatment [40]. Hong Huang et al. prepared
heterostructured g-C 3 N 4 /Ag/TiO 2 microspheres with improved photocatalytic performance under visible light irradiation. As shown in Fig. 7.1, the protonated g-C 3 N 4
sheets were synthesized by calcinating melamine and followed by the protonation in
HCl solution, and TiO 2 nanomaterial was prepared by a typical hydrothermal
method of Ti(OC 4 H 9 ) 4 , and then Ag/TiO 2 microspheres were obtained by depositing
7.2 The Preparation Methods of g-C 3 N 4 /TiO 2 Heterojunction Catalyst
175