hydrothermal treatment followed by dialysis for 24 h. The obtained powder after
dialysis was dried by adding ethanol and centrifuged at 10,000 rpm for 20 min.
Yu et al. (2012) synthesize ZnO/carbon quantum dot nanocomposites by using
one-step hydrothermal method. The nanocomposites exhibit superior photoactivity
under solar light for the decomposition of benzene and methanol, both toxic gases,
and benzene binds by π–π interaction in conjugation between the two moieties. The
higher efficiency of nanocomposites was attributed to the up-conversion emission by
carbon quantum dots under visible region. ZnO loading on carbon quantum dots
constructs a “dyad structure” where the electron is simultaneously transferred to
carbon quantum dots’ surface and the hole remains at the ZnO surface (Scheme 3.2).
The simultaneous transfer of electron onto carbon quantum dots inhibits charge
carrier recombination and increases the lifetime of electron–hole pair. The adsorbed
O 2 on the surface of carbon quantum dots converts into superoxide radical anion,
which is a strong oxidizing agent and easily oxidized the adsorbed toxic gases on the
surface. The up-conversion of emission light means the conversion of longer
Scheme 3.2 Schematic model for the photocatalytic process of ZnO/carbon quantum dot composites under visible light. ZnO loading on carbon quantum dots constructs a “dyad structure” where
electrons simultaneously migrate to the carbon quantum dot surface and holes remain at the ZnO
surface. (CQDs carbon quantum dots). (Reprinted with permission from Yu et al. (2012) copyright@2012, The Royal Society of Chemistry)
96
P. Shandilya et al.
dialysis was dried by adding ethanol and centrifuged at 10,000 rpm for 20 min.
Yu et al. (2012) synthesize ZnO/carbon quantum dot nanocomposites by using
one-step hydrothermal method. The nanocomposites exhibit superior photoactivity
under solar light for the decomposition of benzene and methanol, both toxic gases,
and benzene binds by π–π interaction in conjugation between the two moieties. The
higher efficiency of nanocomposites was attributed to the up-conversion emission by
carbon quantum dots under visible region. ZnO loading on carbon quantum dots
constructs a “dyad structure” where the electron is simultaneously transferred to
carbon quantum dots’ surface and the hole remains at the ZnO surface (Scheme 3.2).
The simultaneous transfer of electron onto carbon quantum dots inhibits charge
carrier recombination and increases the lifetime of electron–hole pair. The adsorbed
O 2 on the surface of carbon quantum dots converts into superoxide radical anion,
which is a strong oxidizing agent and easily oxidized the adsorbed toxic gases on the
surface. The up-conversion of emission light means the conversion of longer
Scheme 3.2 Schematic model for the photocatalytic process of ZnO/carbon quantum dot composites under visible light. ZnO loading on carbon quantum dots constructs a “dyad structure” where
electrons simultaneously migrate to the carbon quantum dot surface and holes remain at the ZnO
surface. (CQDs carbon quantum dots). (Reprinted with permission from Yu et al. (2012) copyright@2012, The Royal Society of Chemistry)
96
P. Shandilya et al.