An improved photosensitizer for a photocathode comprises an oligomeric or polymeric chromphore absorbing, as an ensemble, light at (a) wavelengths at or greater than 420 nm that includes at least 3 identical or different suitable monomeric chromophore units carrying at least two substituents each comprising at least one alkylene, alkenylene and/or alkynylene chain having a chain length of at least 3 carbon atoms, those substituents being terminated by thiol groups, wherein the oligomeric or polymeric chromphore has a disulfide bond between each of the chromophores. A photocathode comprising the photosensitzer is useful for the reduction of water-soluble chemicals in oxidized forms, including protons, with the aid of visible light in a system comprising the photocathode and a photoanode or any other anode or source of electrons. A method for reducing chemicals soluble in aqueous media in oxidized forms, including protons, in aqueous solutions by means of the photocathode is also disclosed.

To improve light energy conversion efficiency of a semiconductor photoelectrode. A semiconductor photoelectrode in which an oxidation reaction of water proceeds on a surface by irradiation with light includes a first semiconductor layer laminated on an insulating or conductive substrate, and a transparent conductive polymer layer laminated on the first semiconductor layer, made of a transparent conductive polymer, and having an activity function of promoting the oxidation reaction of water. Due to the transparency of the transparent conductive polymer layer, light transmittance is improved, and the transparent conductive polymer layer can be laminated on the entire surface of the semiconductor layer, allowing the light energy conversion efficiency of the semiconductor photoelectrode to be improved.

To improve light energy conversion efficiency of a semiconductor photoelectrode. A semiconductor photoelectrode in which an oxidation reaction of water proceeds on a surface by irradiation with light includes a first semiconductor layer laminated on an insulating or conductive substrate, and a transparent conductive polymer layer laminated on the first semiconductor layer, made of a transparent conductive polymer, and having an activity function of promoting the oxidation reaction of water. Due to the transparency of the transparent conductive polymer layer, light transmittance is improved, and the transparent conductive polymer layer can be laminated on the entire surface of the semiconductor layer, allowing the light energy conversion efficiency of the semiconductor photoelectrode to be improved.

The present disclosure relates to a bismuth vanadate electrode including vanadium-functionalized graphene quantum dots and a method for preparing the same. More particularly, it relates to a technology which is capable of, by adding graphene quantum dots (GQDs) in the process of immersing a bismuth vanadate (BiVO.sub.4) electrode in an alkaline solution to remove vanadium oxide (V.sub.2O.sub.5) excessively formed on the surface of the electrode during its preparation, protecting the electrode from the alkaline solution as the graphene quantum dots are adsorbed onto the surface of BiVO.sub.4 while V.sub.2O.sub.5 is removed, and improving the efficiency of oxygen evolution reaction (OER) when applied to a photoanode due to vanadium (V)-functionalized graphene quantum dots formed as the etched vanadium ions ((VO).sub.4.sup.3−) are adsorbed onto the graphene quantum dots.

The present disclosure relates to a hydrogen evolution apparatus including an AC power source, a semiconductor electrode and a counter electrode connected to the AC power source, an electrolyte in which the semiconductor electrode is immersed, and a light source which irradiates light on the semiconductor electrode, in which the semiconductor electrode includes a conductive substrate and n-type semiconductor particles dispersed on a p-type semiconductor matrix or p-type semiconductor particles dispersed on an n-type semiconductor matrix which is vertically grown from the conductive substrate.

A device includes a substrate having a surface, an array of conductive projections supported by the substrate and extending outward from the surface of the substrate, a plurality of catalyst nanoparticles disposed over the array of conductive projections, and an oxide layer covering the plurality of catalyst nanoparticles and the array of conductive projections. The oxide layer has a thickness on the order of a size of each catalyst nanoparticle of the plurality of catalyst nanoparticles.

A device includes a substrate having a surface, an array of conductive projections supported by the substrate and extending outward from the surface of the substrate, a plurality of catalyst nanoparticles disposed over the array of conductive projections, and an oxide layer covering the plurality of catalyst nanoparticles and the array of conductive projections. The oxide layer has a thickness on the order of a size of each catalyst nanoparticle of the plurality of catalyst nanoparticles.

A radiation-assisted (typically solar-assisted) electrolyzer cell and panel for high-efficiency hydrogen production comprises a photoelectrode and electrode pair, with said photoelectrode comprising either a photoanode electrically coupled to a cathode shared with an anode, or a photocathode electrically coupled to an anode shared with a cathode; electrolyte; gas separators; all within a container divided into two chambers by said shared cathode or shared anode, and at least a portion of which is transparent to the electromagnetic radiation required by said photoanode (or photocathode) to apply photovoltage to a shared cathode (or anode) that increases the electrolysis current and hydrogen production.

A synthesis gas production system for producing CO and H.sub.2 by electrolyzing an aqueous solution containing CO.sub.2 includes: an electrolysis device including an anode chamber and a cathode chamber separated by a separator membrane; a cathode-side circulation line connected to the cathode chamber to circulate a cathode solution containing CO.sub.2; a catalyst supply device provided in the cathode-side circulation line to supply a CO production catalyst to the cathode solution; and a gas composition detection device configured to measure a ratio between CO and H.sub.2 in a production gas produced in the cathode chamber. At least one of control of a supply amount of the CO production catalyst by the catalyst supply device and control of a voltage applied between the anode and the cathode by the electrolysis device is performed to make a ratio of H.sub.2 to CO in the production gas be within a predetermined target range.

An object of the present invention is to provide a photocatalyst for water splitting, which can form a water splitting device that is excellent in durability and responsiveness to visible light and excellent in the amount of generated gas, and a water splitting device having the photocatalyst for water splitting. A photocatalyst for water splitting according to the embodiment of the present invention is a photocatalyst for water splitting, which is used for an electrode that generates gas by irradiation with light in a state of being immersed in water, and includes a compound represented by a formula, (Ln).sub.2CuO.sub.4. In the formula, Ln represents a lanthanoid, and a part of Ln's may be substituted with an element of Groups II to IV of the periodic table.