Stress-induced bandgap-shifted semiconductor photoelectrolytic/photocatalytic/photovoltaic surface and method for making same
OwnerJohn Michael Guerrainventor
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Abstract
Titania is a semiconductor and photocatalyst that is also chemically inert. With its bandgap of 3.0, to activate the photocatalytic property of titania requires light of about 390 nm wavelength, which is in the ultra-violet (UV), where sunlight is very low in intensity. A method and devices are disclosed wherein stress is induced and managed in a thin film of titania in order to shift and lower the bandgap energy into the longer wavelengths that are more abundant in sunlight. Applications of this stress-induced bandgap-shifted titania photocatalytic surface include photoelectrolysis for production of hydrogen gas from water, photovoltaics for production of electricity, and photocatalysis for detoxification and disinfection.
Claims17
A semiconductor film on a substrate, the semiconductor film having a bandgap not supporting spontaneous photoelectrolysis of water in visible light wavelengths present in sunlight, the substrate having surface undulations with a spatial period smaller than the wavelength of visible light that cause stress in the semiconductor film and thereby shift the bandgap therein to support spontaneous photoelectrolysis of water in visible light.
A photoelectrolytic cell device for dissociation and production of hydrogen gas from an aqueous solution when illuminated, the cell comprising:
- a substrate having undulations on a surface thereof, the undulations having a spatial period smaller than a wavelength of an illuminant in the visible spectrum;
- a semiconductor film on the substrate surface, the semiconductor film having a bandgap not supporting spontaneous photoelectrolysis of water in visible light, the surface undulations of the substrate causing stress in the semiconductor film and thereby shifting the bandgap therein to support spontaneous photoelectrolysis of water in the visible light;
- and
- an aqueous electrolyte in contact with the semiconductor film.
Dependencies are inferred from the claim text.