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Hydrogen production: Semiconductor based photoelectrochemical (PEC) water splitting
Hydrogen production: Semiconductor based photoelectrochemical (PEC) water splitting
The production of hydrogen from water splitting is an ideal future energy source, independent of fossil fuels. The solar energy is a free and inexhaustible resource. Hydrogen is clean energy. An engine that burns pure hydrogen produces almost no pollution. Liquid hydrogen is used to propel the space shuttle in NASA. Also hydrogen fuel cell producing a clean byproduct is researched very well. In the future, hydrogen could join an important energy as an electricity.
The production of hydrogen from water splitting is an ideal future energy source, independent of fossil fuels. The solar energy is a free and inexhaustible resource. Hydrogen is clean energy. An engine that burns pure hydrogen produces almost no pollution. Liquid hydrogen is used to propel the space shuttle in NASA. Also hydrogen fuel cell producing a clean byproduct is researched very well. In the future, hydrogen could join an important energy as an electricity.
In the case of semiconductor-based photoelectrochemical cell, the bandgap energy is crucial factor to hydrogen production by water splitting. Picture is basic principle of water splitting and present the band location and minimum bandgap energy. The conduction band of semiconductor must be located at a more negative potential than the reduction potential H+/H2 (0 V), while the valance band of semiconductor must be located at a more positive potential than the oxidation potential H2O/O2 (1.23 V). Therefore, the minimum bandgap energy of semiconductor is 1.23 eV. It is equivalent to the energy of photon with wavelength 1010 nm, that is, visible light.
In the case of semiconductor-based photoelectrochemical cell, the bandgap energy is crucial factor to hydrogen production by water splitting. Picture is basic principle of water splitting and present the band location and minimum bandgap energy. The conduction band of semiconductor must be located at a more negative potential than the reduction potential H+/H2 (0 V), while the valance band of semiconductor must be located at a more positive potential than the oxidation potential H2O/O2 (1.23 V). Therefore, the minimum bandgap energy of semiconductor is 1.23 eV. It is equivalent to the energy of photon with wavelength 1010 nm, that is, visible light.
Hydrogen production using photoelectrochemical (PEC) water splitting has attracted significant attention as a hot research topic to solve environmental problems resulting from fossil fuel use and greenhouse gas generation. In PEC water splitting, hydrogen and oxygen are obtained by a chemical reaction that occurs after charge-separated electrons and holes are generated when the semiconductor absorbs sunlight. Among the components of a PEC water-splitting cell, the photoabsorber, which directly absorbs sunlight, and electrocatalysts, which activate the carrier transfer process, are very important for achieving a high level of efficiency.
Hydrogen production using photoelectrochemical (PEC) water splitting has attracted significant attention as a hot research topic to solve environmental problems resulting from fossil fuel use and greenhouse gas generation. In PEC water splitting, hydrogen and oxygen are obtained by a chemical reaction that occurs after charge-separated electrons and holes are generated when the semiconductor absorbs sunlight. Among the components of a PEC water-splitting cell, the photoabsorber, which directly absorbs sunlight, and electrocatalysts, which activate the carrier transfer process, are very important for achieving a high level of efficiency.
Evaluation of Electroless and Electron Beam Pt on p-GaAs as a Photocathode
Evaluation of Electroless and Electron Beam Pt on p-GaAs as a Photocathode
Reflectance spectra and calculated SWR of Pt on GaAs deposited using (A) ED and (B) EE as a function of the deposition time.
Reflectance spectra and calculated SWR of Pt on GaAs deposited using (A) ED and (B) EE as a function of the deposition time.
LSV characterization of p-GaAs photocathodes after electroless Pt deposition and (B) change in open circuit potential (Voc) and saturation current density (Jst) according to the deposition time for bare and 10, 20, 80, 120, and 160 s operations. The solid and dashed lines indicate the current measured under 1SUN illumination and without illumination in (A), respectively.
LSV characterization of p-GaAs photocathodes after electroless Pt deposition and (B) change in open circuit potential (Voc) and saturation current density (Jst) according to the deposition time for bare and 10, 20, 80, 120, and 160 s operations. The solid and dashed lines indicate the current measured under 1SUN illumination and without illumination in (A), respectively.
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