catalyst possesses better catalytic effect than that of single-component catalyst.
Nowadays, there have been a great number of materials which can be used to modify
TiO 2 by forming the heterojunction structure, such as ZnO [24, 25], SnO 2 [26, 27],
g-C 3 N 4 , etc. [28–31]. Among them, g-C 3 N 4 as a stable nonmetal semiconductor has
attracted much attention in the catalytic field. Due to its special triazine structure,
g-C 3 N 4 exhibits many special properties including low density, high chemical
stability, enhanced biological compatibility, good abrasion resistance, and so
on. In addition, the relatively narrow bandgap of g-C 3 N 4 (about 2.7 eV) extends
its light response to visible region (about 450 nm). Zhang et al. reported that the
g-C 3 N 4 exhibited high photocatalytic performance for water splitting under visible
light irradiation [32]. Dong and coworkers facilely synthesized polymeric g-C 3 N 4 -
layered catalyst by directly heating urea or thiourea [33, 34]. In the research on
heterojunction catalysts, g-C 3 N 4 has gained the majority of researchers’ attention
owing to its simple preparation method, abundant kinds of precursors, as well as the
advantages of low cost, becoming the first choice to form heterojunction with TiO 2 .
In this chapter, the recent developments of the research on the heterojunction
photocatalysts formed by g-C 3 N 4 and TiO 2 were introduced, including its synthesis
methods and applications. Firstly, the synthesis methods were summarized based on
the synthesis order of each component during the preparation process and divided
into three categories. In each category, the preparation procedures as well as their
advantages and drawbacks were introduced in detail. Through these synthesis
methods, an efficient heterojunction structure can be obtained between g-C 3 N 4 and
TiO 2 . The photocatalytic activity of the photocatalysts can be greatly enhanced due
to the formation of the heterojunction structure, which can effectively promote the
separation of photo-generated charge carriers [35, 36]. The excellent photocatalytic
activity of the g-C 3 N 4 /TiO 2 heterojunction photocatalysts enables them to be applied
in many aspects. Therefore, the chapter also introduced the applications of g-C 3 N 4 /
TiO 2 heterojunction photocatalysts in the field of photocatalysis, containing
depollution of environment, hydrogen generation, photofixation of carbon dioxide,
bacteria disinfection, and so on. In the end of the chapter, a short summary and
outlook on the development of g-C 3 N 4 /TiO 2 heterojunction photocatalysts were
provided.
7.2 The Preparation Methods of g-C 3 N 4 /TiO 2
Heterojunction Catalyst
Because the g-C 3 N 4 /TiO 2 heterojunction photocatalyst consists of two singlecomponent g-C 3 N 4 and TiO 2 , the synthesis methods of g-C 3 N 4 /TiO 2 heterojunction
catalyst can be classified into three categories according to the order of synthesis of
each component: (1) physically mixing TiO 2 and g-C 3 N 4 , (2) growing g-C 3 N 4 on
TiO 2 catalyst, and (3) loading TiO 2 on g-C 3 N 4 catalyst. No matter what the method
174
7 The Preparation and Applications of g-C 3 N 4 /TiO 2 Heterojunction Catalysts
Nowadays, there have been a great number of materials which can be used to modify
TiO 2 by forming the heterojunction structure, such as ZnO [24, 25], SnO 2 [26, 27],
g-C 3 N 4 , etc. [28–31]. Among them, g-C 3 N 4 as a stable nonmetal semiconductor has
attracted much attention in the catalytic field. Due to its special triazine structure,
g-C 3 N 4 exhibits many special properties including low density, high chemical
stability, enhanced biological compatibility, good abrasion resistance, and so
on. In addition, the relatively narrow bandgap of g-C 3 N 4 (about 2.7 eV) extends
its light response to visible region (about 450 nm). Zhang et al. reported that the
g-C 3 N 4 exhibited high photocatalytic performance for water splitting under visible
light irradiation [32]. Dong and coworkers facilely synthesized polymeric g-C 3 N 4 -
layered catalyst by directly heating urea or thiourea [33, 34]. In the research on
heterojunction catalysts, g-C 3 N 4 has gained the majority of researchers’ attention
owing to its simple preparation method, abundant kinds of precursors, as well as the
advantages of low cost, becoming the first choice to form heterojunction with TiO 2 .
In this chapter, the recent developments of the research on the heterojunction
photocatalysts formed by g-C 3 N 4 and TiO 2 were introduced, including its synthesis
methods and applications. Firstly, the synthesis methods were summarized based on
the synthesis order of each component during the preparation process and divided
into three categories. In each category, the preparation procedures as well as their
advantages and drawbacks were introduced in detail. Through these synthesis
methods, an efficient heterojunction structure can be obtained between g-C 3 N 4 and
TiO 2 . The photocatalytic activity of the photocatalysts can be greatly enhanced due
to the formation of the heterojunction structure, which can effectively promote the
separation of photo-generated charge carriers [35, 36]. The excellent photocatalytic
activity of the g-C 3 N 4 /TiO 2 heterojunction photocatalysts enables them to be applied
in many aspects. Therefore, the chapter also introduced the applications of g-C 3 N 4 /
TiO 2 heterojunction photocatalysts in the field of photocatalysis, containing
depollution of environment, hydrogen generation, photofixation of carbon dioxide,
bacteria disinfection, and so on. In the end of the chapter, a short summary and
outlook on the development of g-C 3 N 4 /TiO 2 heterojunction photocatalysts were
provided.
7.2 The Preparation Methods of g-C 3 N 4 /TiO 2
Heterojunction Catalyst
Because the g-C 3 N 4 /TiO 2 heterojunction photocatalyst consists of two singlecomponent g-C 3 N 4 and TiO 2 , the synthesis methods of g-C 3 N 4 /TiO 2 heterojunction
catalyst can be classified into three categories according to the order of synthesis of
each component: (1) physically mixing TiO 2 and g-C 3 N 4 , (2) growing g-C 3 N 4 on
TiO 2 catalyst, and (3) loading TiO 2 on g-C 3 N 4 catalyst. No matter what the method
174
7 The Preparation and Applications of g-C 3 N 4 /TiO 2 Heterojunction Catalysts