CdSe Quantum Dots
Photocatalysis is another important potential application for quantum dots
(QDs). Photocatalysis is the process by which solar energy is converted
into chemical energy for environmental remediation and chemical synthesis.
It offers exciting opportunities in the development of renewable energy
sources and environmentally friendly chemical processes. Semiconductor
compositions can catalyze reactions upon the absorption of light because
the electron-hole pairs generated by solar radiation can catalyze redox
reactions. Currently, the most frequently studied photocatalytic material
is TiO2. This material has shown great promise, with many beneficial properties.
However, TiO2 powder only absorbs light in the visible part of the energy
spectrum (TiO2 powder can only harvest 3% of the solar spectrum). Thus,
great interest has recently developed in semiconductor materials that absorb
light in the visible part of the solar energy spectrum, since most solar
energy is in the visible region.
Lots of studies have shown that QD colloid suspensions, such as CdS, ZnS,
MoS2, SnO2, ZnO, and TiO2, can serve as photocatalysts for a variety of
reactions. Some of these materials, such as CdS, ZnS, ZnO, and TiO2, can
only absorb light in the UV region; MoS2 and SnO2 can work as photocatalysts
under visible light. The benefit of using QDs as photocatalysts is that
the colloid suspension can eliminate light scattering losses, provide a
very large surface area, and the electron and hole redox potentials of
the QDs can be tuned to achieve increased redox power. However, the prospect
of QDs as candidates for replacing TiO2 is low, mostly due to the greater
susceptibility to photocorrosion caused by the greater exposed surface
area. A good way to enhance the photostability and quantum yield is coating
the bare QDs with a shell of another semiconductor material, such as CdSe/CdS,
CdS/Cd(OH)2, CdSe/ZnS. Thus this system of materials holds exciting promise
for working as a photocatalyst with high stability and high efficiency.
This system has not yet been explored for photocatalysis
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