antibacterial property was enhanced under ultraviolet photo-irradiation, which is
attributed to the production of reactive oxidation species responsible for membrane
damage as confirmed by paramagnetic resonance and fluorescence microscopic
measurements. The ZnO/graphene quantum dot nanocomposites exhibit higher
bactericidal effect as compared to ZnO and graphene quantum dots, which may be
accounted due to the interfacial charge transfer from graphene quantum dots to ZnO
surface that enhances the generation of reactive oxidation species.
3.6 Conclusion
Carbon quantum dots recently emerge as important nanomaterials among various
available carbonaceous materials due to their unique properties. Carbon quantum
dots are visible light-driven photocatalysts which exhibit special up-conversion
phenomena in which they convert longer wavelength light into shorter wavelength
with high-energy photon that is efficiently employed for the excitation of charge
carrier from the surface of wide band gap semiconductor. The property of
up-conversion validates carbon quantum dot usage as photosensitizer as well as
photocatalyst. Besides their many applications in different fields, carbon quantum
dot-based nanocomposites can also be efficiently used as antimicrobial agents.
Carbon quantum dots displayed not only antibacterial but also antifungal property.
The antibacterial activity of carbon quantum dot-based nanocomposites is basically
due to the generation of reactive oxidation species which may cause oxidative stress
as well as disruption of the cell membrane. The book chapter provides a basic review
of various synthetic methods for the preparation of carbon quantum dot-based
nanocomposites and utilization as photocatalyst. Though significant efforts have
already been done on carbon quantum dots over the past 15 years, they are still
facing many challenges. From the future prospective, understanding the concept
behind up-conversion mechanism of carbon quantum dots, increasing yield of
carbon quantum dots, optimization of synthetic procedure for better control over
size, increasing photostability of carbon quantum dots, or minimizing photobleaching and green method to avoid chemical pollution need to be addressed before
practical application. The literature survey reveals that studies were limited to certain
basic pollutants like methylene blue, methyl orange, rhodamine B, and phenol. Thus,
photodegradation by carbon quantum dots needs further extension to other pollutants
as well, applying it to pollutants belonging in the real world. Lastly, photo-efficiency
and separation of carbon quantum dots are also important issues, as no such
photocatalyst is designed yet which shows high efficiency for degradation of pollutants. Despite the many challenges associated with carbon quantum dots, numerous opportunities are still waiting to explore endless potential to be employed in
various technologies.
3 Metal and Carbon Quantum Dot Photocatalysts for Water Purification
107
attributed to the production of reactive oxidation species responsible for membrane
damage as confirmed by paramagnetic resonance and fluorescence microscopic
measurements. The ZnO/graphene quantum dot nanocomposites exhibit higher
bactericidal effect as compared to ZnO and graphene quantum dots, which may be
accounted due to the interfacial charge transfer from graphene quantum dots to ZnO
surface that enhances the generation of reactive oxidation species.
3.6 Conclusion
Carbon quantum dots recently emerge as important nanomaterials among various
available carbonaceous materials due to their unique properties. Carbon quantum
dots are visible light-driven photocatalysts which exhibit special up-conversion
phenomena in which they convert longer wavelength light into shorter wavelength
with high-energy photon that is efficiently employed for the excitation of charge
carrier from the surface of wide band gap semiconductor. The property of
up-conversion validates carbon quantum dot usage as photosensitizer as well as
photocatalyst. Besides their many applications in different fields, carbon quantum
dot-based nanocomposites can also be efficiently used as antimicrobial agents.
Carbon quantum dots displayed not only antibacterial but also antifungal property.
The antibacterial activity of carbon quantum dot-based nanocomposites is basically
due to the generation of reactive oxidation species which may cause oxidative stress
as well as disruption of the cell membrane. The book chapter provides a basic review
of various synthetic methods for the preparation of carbon quantum dot-based
nanocomposites and utilization as photocatalyst. Though significant efforts have
already been done on carbon quantum dots over the past 15 years, they are still
facing many challenges. From the future prospective, understanding the concept
behind up-conversion mechanism of carbon quantum dots, increasing yield of
carbon quantum dots, optimization of synthetic procedure for better control over
size, increasing photostability of carbon quantum dots, or minimizing photobleaching and green method to avoid chemical pollution need to be addressed before
practical application. The literature survey reveals that studies were limited to certain
basic pollutants like methylene blue, methyl orange, rhodamine B, and phenol. Thus,
photodegradation by carbon quantum dots needs further extension to other pollutants
as well, applying it to pollutants belonging in the real world. Lastly, photo-efficiency
and separation of carbon quantum dots are also important issues, as no such
photocatalyst is designed yet which shows high efficiency for degradation of pollutants. Despite the many challenges associated with carbon quantum dots, numerous opportunities are still waiting to explore endless potential to be employed in
various technologies.
3 Metal and Carbon Quantum Dot Photocatalysts for Water Purification
107