Modification Strategies of g-C3N4 for Potential Applications in Photocatalysis 305

17.5.4 Other Applications

These composites have a wide range of different uses because of the distinct characteristics of

g-C3N4 based heterojunctions (Vignesh et al. 2019). Rechargeable Lithium-Ion Batteries (LIBs)

have drawn a great deal of academic interest due to the rising energy demand for electronic gadgets

and automobiles (Li et al. 2015). Anode materials, which comprise a sizeable portion of LIBs,

should have higher stability and increased specific capacity. The hydrothermal approach was used

by (Tran et al. 2019) to develop SnO2 on the graphite oxide/g-C3N4. SnO2 is a novel lipophilic

material with a high specific capacity, low Li⁺ insertion potential, greater number of sources

and other characteristics. This composite demonstrated high cycling and reversible capacity for

lithium storage, possibly due to the presence of graphite oxide-g-C3N4 or g-C3N4. SnO2@g­

C3N4 based nanocomposites can replace next-generation high-power and low-cost LIBs. Another

use for g-C3N4 based materials is in producing NH3 by photocatalytic nitrogen fixation, which is

an environmentally friendly and long-lasting process. However, g-effectiveness C3N4’s for nitrogen

fixation activities has been constrained by low stability, negligible surface-active sites and a high

carrier recombination rate. The carrier separation should be improved by doping with additional

elements or composing with other metal oxides. For the reduction processes, nitrogen gas should

finally totally adsorb on the photocatalyst. According to (Kong et al. 2020), the cyano group in

g-C3N4 modified by the cyano group increases the photocatalytic activities for N2 fixation by up to

128 times. As explained earlier, sulfur and iodine can enhance the carriers’ activities in the bulk of

g-C3N4. The fact that g-C3N4 -metal oxide-based heterojunction may be widely employed to detect

various heavy metals, gases, biological materials and organic and inorganic compounds (Ahmad

et al. 2020). Supercapacitors and desulfurization are two further applications for g-C3N4-metal

oxide-based composites that could be utilized extensively (Ma et al. 2019).

17.6 Conclusion

g-C3N4 is a metal-free semiconductor with an adjustable band gap, excellent chemical and thermal

stability and appealing electrical characteristics. Graphitic carbon nitride absorbs UV light and has

a band gap of 2.7 eV. Modifying g-C3N4 via doping and blending with other materials to produce

composites can result in improved optoelectronic characteristics, and the composites can exhibit

synergistic properties. Many studies used doping elements to increase the effectiveness of bare

g-C3N4 light harvesting, while mixing g-C3N4 with other materials, such as metals, metal oxides and

nonmetals is another strategy to deal with this issue. The examination of g-C3N4 heterojunctions with

designed bandgaps and optimized surfaces to improve the absorption spectrum towards the visible-

light region, reduced charge carrier recombination, and increased surface adsorption and reaction

are among the critical areas of g-C3N4 based material research. The highlighted applications of

modified g-C3N4 included water splitting, bacterial disinfection, energy storage, photodegradation

of organic pollutants, CO2 reduction, sensing, etc. Even though most recent research has shown that

g-C3N4-based photocatalysts work very well, their full potential has not yet been fully realized. The

main problems are in finding a green way to make a photocatalyst with a high surface area and good

photostability, testing how well a g-C3N4 based photocatalyst works with real industrial wastewater

and improving reactor design to get the best photocatalytic activity.

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