2.2 Quantum Dots and Water Splitting Reaction
15
2.2 Quantum Dots and Water Splitting Reaction
Quantum dots are very significant nanoentities. They are nanoscale crystals with the
ability to transport electrons. They have widespread applications in water splitting
reactions. In a study conducted by Wang et al. a useful set of quantum dots were
discovered which have proven their worth as promising electrocatalysts for water
splitting reaction and liberation of hydrogen. In this investigation, a hybrid structure
of carbon quantum dots attached to the single-layer C 3 N was studied. The firstprinciple calculations have depicted that the hybrid is capable of gathering visible
and infrared light. These hybrid structures were also able to prevent the mixing of
hydrogen and oxygen after their liberation from water splitting. This was due to the
fact that the hybrid has sites where redox reaction can occur, and this ensured fast
deliveries of the photogenerated holes and electrons to the outer C 3 N monolayer and
inner quantum dots of carbon. The electrostatic forces of attraction forced the protons
to penetrate through the monolayer and enter the quantum dots to liberate hydrogen
during electrolysis. As no oxygen or hydrogen entered the hybrid, the mixing of the
gases was prevented. These metal-free quantum dots-assisted hybrids are appealing
candidate for solar energy-driven water splitting reactions with minimum or no
mixing of the gases [6].
Quantum dots prepared with copper oxide and supported on titanium oxide
nanosheets are reported to have excellent hydrogen liberation ability via water splitting reaction. The hybrid of CuO quantum dots and TiO 2 has shown the hydrogen
liberation rate of ∼0.04 mmol h
−1 which is approximately 20 times greater than
pure nanosheets of TiO 2 . This CuO/TiO 2 hybrid was prepared by mixing of titanium (IV) butoxide and HCl. This mixture after stirring for 30 min was placed in
Teflon autoclave where hydrothermal reaction occurs, and precipitates were formed
which were separated by centrifugation. The residual fluoride ions were removed
by treatment of the product with NaOH, and afterward the product was rinsed with
deionized (DI) water and fine powder of TiO 2 was obtained. Later on, CuO quantum
dots were deposited on the prepared nanosheets by the general hydrothermal procedure. In this process, CuCl 2 was added in the ethanol suspension of TiO 2 nanosheets.
After continuous stirring for 5 h, ethanol was evaporated in drying oven. Later on,
the product was calcinated at 400 °C in muffle furnace, as the product cooled the
CuO quantum dots accumulated on the TiO 2 nanosheets. The prepared product was
characterized with XRD, XPS, SEM, TEM, and UV–vis diffusion reflectance spectra
(DRS) [7].
Ye et al. have reported Pt quantum dot ornamented αFe 2 O 3 nanosheets for efficient
liberation of hydrogen gas from electrochemical splitting of water. These nanostructures were found to be very efficient in water splitting reaction as they have
several active sites, and they exhibited low overpotential i-e 90 mV@10 mA cm
−2
for hydrogen evolution reaction and a considerably low voltage of 1.51 V in alkaline
electrolyte. The flower-like nanostructure was prepared by the electrodeposition and
impregnation deposition. The pretreated Ni-foam and graphite were used as cathode
15
2.2 Quantum Dots and Water Splitting Reaction
Quantum dots are very significant nanoentities. They are nanoscale crystals with the
ability to transport electrons. They have widespread applications in water splitting
reactions. In a study conducted by Wang et al. a useful set of quantum dots were
discovered which have proven their worth as promising electrocatalysts for water
splitting reaction and liberation of hydrogen. In this investigation, a hybrid structure
of carbon quantum dots attached to the single-layer C 3 N was studied. The firstprinciple calculations have depicted that the hybrid is capable of gathering visible
and infrared light. These hybrid structures were also able to prevent the mixing of
hydrogen and oxygen after their liberation from water splitting. This was due to the
fact that the hybrid has sites where redox reaction can occur, and this ensured fast
deliveries of the photogenerated holes and electrons to the outer C 3 N monolayer and
inner quantum dots of carbon. The electrostatic forces of attraction forced the protons
to penetrate through the monolayer and enter the quantum dots to liberate hydrogen
during electrolysis. As no oxygen or hydrogen entered the hybrid, the mixing of the
gases was prevented. These metal-free quantum dots-assisted hybrids are appealing
candidate for solar energy-driven water splitting reactions with minimum or no
mixing of the gases [6].
Quantum dots prepared with copper oxide and supported on titanium oxide
nanosheets are reported to have excellent hydrogen liberation ability via water splitting reaction. The hybrid of CuO quantum dots and TiO 2 has shown the hydrogen
liberation rate of ∼0.04 mmol h
−1 which is approximately 20 times greater than
pure nanosheets of TiO 2 . This CuO/TiO 2 hybrid was prepared by mixing of titanium (IV) butoxide and HCl. This mixture after stirring for 30 min was placed in
Teflon autoclave where hydrothermal reaction occurs, and precipitates were formed
which were separated by centrifugation. The residual fluoride ions were removed
by treatment of the product with NaOH, and afterward the product was rinsed with
deionized (DI) water and fine powder of TiO 2 was obtained. Later on, CuO quantum
dots were deposited on the prepared nanosheets by the general hydrothermal procedure. In this process, CuCl 2 was added in the ethanol suspension of TiO 2 nanosheets.
After continuous stirring for 5 h, ethanol was evaporated in drying oven. Later on,
the product was calcinated at 400 °C in muffle furnace, as the product cooled the
CuO quantum dots accumulated on the TiO 2 nanosheets. The prepared product was
characterized with XRD, XPS, SEM, TEM, and UV–vis diffusion reflectance spectra
(DRS) [7].
Ye et al. have reported Pt quantum dot ornamented αFe 2 O 3 nanosheets for efficient
liberation of hydrogen gas from electrochemical splitting of water. These nanostructures were found to be very efficient in water splitting reaction as they have
several active sites, and they exhibited low overpotential i-e 90 mV@10 mA cm
−2
for hydrogen evolution reaction and a considerably low voltage of 1.51 V in alkaline
electrolyte. The flower-like nanostructure was prepared by the electrodeposition and
impregnation deposition. The pretreated Ni-foam and graphite were used as cathode