Devices for photoelectrodes for water splitting based on indium nanowires on flexible substrates as well as methods of manufacture by transferring nanowire arrays to flexible substrates.

Embodiments provide novel devices, nanowires, apparatuses, artificial leaves, photoelectrodes and membranes for photochemical energy production and methods of fabricating the same. The devices, apparatuses, artificial leaves, photoelectrodes, and membranes are planar and are embedded with nanowires, including InGaN nanowires. The unique devices, artificial leaves, apparatuses photoelectrodes, and nanowire-embedded membranes provide a high degree of flexibility and incorporate a large amount of indium, making them valuable for use for hydrogen production from sunlight and water. Embodiments also provide flexible substrates combining water oxidation and hydrogen reduction in a seamless manner to enhance the overall efficiency of water splitting.

A semiconductor photoelectrode that is to be located in an aqueous solution to cause a decomposition reaction of the aqueous solution upon being irradiated with light, the semiconductor photoelectrode including: a semiconductor layer that is formed on an insulative or conductive substrate and is provided with a plurality of protrusion structures that protrude in one direction that is opposite a direction in which the substrate is located; a catalyst layer that is continuously laminated on the surface of the semiconductor layer; and a wire that is electrically connected to the semiconductor layer.

A photochemical electrode includes: an electrically-conductive layer; and a photo-excited material layer including a photo-excited material provided over the electrically-conductive layer, wherein in a surface of the photo-excited material layer, a lattice plane having highest atomic density in a crystal structure of the photo-excited material is oriented in a surface direction of the surface of the photo-excited material layer.

A photochemical electrode includes: an electrically conductive layer; and a photoexcitation material layer provided over the electrically conductive layer and including a photoexcitation material, wherein the photoexcitation material layer is one of a first photoexcitation material layer in which a potential of the conduction band minimum decreases from a second surface opposite to a first surface on the side of the electrically conductive layer toward the first surface and a second photoexcitation material layer in which a potential of the valence band maximum decreases from the second surface toward the first surface.

The present disclosure provides a fuel production method and a fuel production apparatus which efficiently convert solar light energy into a fuel. The fuel production apparatus of the present disclosure includes a laminate, an electrolytic bath, and a support tool or a proton permeable membrane. The laminate includes a photoelectromotive layer having a p-n junction structure, a cathode electrode, an anode electrode and a side surface insulating layer, and the photoelectromotive layer includes a semiconductor layer that absorbs light in a near-infrared region with a wavelength of 900 nm or more. In the fuel production apparatus, an underwater optical path length is set to an optimum design value, so that even light in a near-infrared region with a wavelength of 900 nm or more is sufficiently utilized to efficiently convert light energy into at least one fuel selected from hydrogen, carbon monoxide, formic acid, methane, ethylene, methanol, ethanol, isopropanol, allyl alcohol, acetaldehyde and propionaldehyde through a reduction reaction on the cathode electrode.

Disclosed is a semiconductor-liquid junction based photoelectrochemical (PEC) cell for the unassisted solar splitting of water into hydrogen and oxygen gas, the solar-driven reduction of CO.sub.2 to higher-order hydrocarbons, and the solar-driven synthesis of NH.sub.3. The disclosed system can employ a photocathode based upon wurtzite hexagonal semiconductors that can be tailored with proper band alignment for the redox potentials for water, CO.sub.2 reduction, and NH.sub.3 production, and with bandgap energy for maximum solar absorption. The design maximizes the carrier collection efficiency by leveraging spontaneous and piezoelectric polarization in these materials systems to generate hot electrons within the photocathode. These electrons have sufficient excess energy, preserved at a designed energy capture region, to overcome the kinetic overpotential (surface chemistry limitation) required for the reactions to occur at a high rate.

A photochemical electrode includes: an electrically conductive layer; and a photoexcitation material layer provided over the electrically conductive layer and including a photoexcitation material, wherein the photoexcitation material layer is one of a first photoexcitation material layer in which a potential of the conduction band minimum decreases from a second surface opposite to a first surface on the side of the electrically conductive layer toward the first surface and a second photoexcitation material layer in which a potential of the valence band maximum decreases from the second surface toward the first surface.

A photochemical electrode includes: an electrically-conductive layer; and a photo-excited material layer including a photo-excited material provided over the electrically-conductive layer, wherein in a surface of the photo-excited material layer, a lattice plane having highest atomic density in a crystal structure of the photo-excited material is oriented in a surface direction of the surface of the photo-excited material layer.

A method for fabricating a film on a substrate and a method for controlling the heating rate of a plurality of nanoparticles to transform the plurality of nanoparticles into a plurality of nanorods and nano-cone structures includes the steps of providing a sol precursor, providing a substrate, depositing the sol precursor onto the substrate via a sol-gel technique, annealing the sol precursor under ambient pressure at a controlled heating rate, and cooling down the sol precursor to form a film.