Figure. 17.1. Triazine and heptazine structures of g-C3N4

Figure 17.1. Triazine and heptazine structures of g-C3N4.

Modification Strategies of g-C3N4 for Potential Applications in Photocatalysis 293

employed in several applications, particularly those connected to energy. The energy needed to make

electricity and heat will double by 2050, primarily because of industrialization, urbanization and

population growth (Dai et al. 2012) ). Oil, coal and other fossil fuels should be used less often since

they negatively influence the environment (Ong et al. 2016). Solar power and photocatalysis are two

solutions (Hasanvandian et al. 2022). Both need appropriate semiconductors, such as g-C3N4, that

have high activity for various catalytic processes, including water splitting, hydrogen production,

the degradation of organic pollutants and the conversion of CO2 (Zou et al. 2018, Arumugam

et al. 2022, Yang et al. 2022). Additionally, g-C3N4 can be utilized to clean wastewater and control

microorganisms (Zhang et al. 2019).

This chapter has focused on several broad details on the characterization and structure of bare

g-C3N4. Some possible adjustments, including doping to improve the characteristics of g-C3N4 are

also discussed. The studies on altering the structure and characteristics of g-C3N4 to increase its

effectiveness for various applications by mixing it with metals, metal oxides and nonmetals have

been described. In the final section of this chapter, the authors have made several recommendations

for prospective future studies in this area which, to our knowledge, have not yet been done.

17.2 Structure and Properties of g-C3N4

Carbon Nitride (CN) has been studied since 1834 when Berzelius made the first linear CN polymer,

which he called “melon” (Liebig 1834). Since then, the CN has been studied. In 1922, Franklin

discovered a specific form of graphitic carbon nitride by letting mercuric thiocyanate break down in

heat (Franklin 1922). In 1989, it was hypothesized that a substance known as -C3N4 could be created

if carbon replaced silica in the structure of Silicon Nitride (Si3N4). Liu and Cohen (1989), Teter

and Hemley (1996) predicted that there would be five different phases of CN: α-C3N4, β-C3N4,

c-C3N4, p-C3N4 and g-C3N4. Except for g-C3N4, all CNs are rigid materials based on their crystal

structures. So, g-C3N4 is much easier to change in shape and structure. As a result, the research of

g-C3N4 gained popularity, and other varieties of g-C3N4 were created.

In g-C3N4, both the N and C atoms are sp² hybridized. They are linked together by bonds, which

make a hexagonal shape. This six-atom ring is the triazine ring (Figure 17.1). A small unit connects

the three triazine rings to a C-N bond. The N atom at the end of each triazine ring in g-C3N4 connects

it to the following ring. This makes a planar grid structure that can grow indefinitely. The C and N

atoms in g-C3N4 are both sp² hybridized, allowing them to form strongly conjugated bonds with lone