The present invention provides a water electrolysis method comprising: supplying at least water into an electrolysis cell which includes a solid polymer electrolyte membrane, and an anode and a cathode disposed sandwiching the solid polymer electrolyte membrane therebetween; and providing a potential P between the anode and the cathode to generate oxygen from the anode, wherein an oxidation catalyst containing at least one of first transition metals is present on at least a part of a surface of the anode, and the potential P satisfies P1<P<P2, wherein P1 indicates a lowest potential at which oxygen is generated from the anode, and P2 indicates a lowest potential P2 at which a quantitative index of a dissolved chemical species derived from the oxidation catalyst begins to show potential dependence.

The present disclosure broadly relates to a process for preparing aqueous solutions of vanadium sulfates or aqueous solutions of transition metal sulfates. More specifically, but not exclusively, the present disclosure relates to a direct electrochemical process in which a suspension, obtained by slurrying transition metals oxides such as oxides of vanadium, oxides of iron, oxides of cobalt, oxides of nickel, oxides of chromium, oxides of manganese, oxides of titanium, oxides of cerium, oxides of praseodymium, oxides of europium, oxides of terbium, oxides of uranium, oxides of plutonium, or their mixtures thereof with sulfuric acid as carrier fluid, is reduced electrochemically inside the cathode compartment of an electrolyzer to produce an aqueous solution of vanadium sulfates or of transition metal sulfates. Simultaneously, oxidizing co-products are produced in the anode compartment.

The invention relates to a layered double hydroxide (LDH) material and methods for using the LDH material to catalyse the oxygen evolution reaction (OER) in a water-splitting process. The invention also provides a composition, a catalytic material, an electrode and an electrolyser including the LDH material. In particular, the LDH material includes a metal composite including cobalt, iron, chromium and optionally nickel species interspersed with a hydroxide layer.

The invention relates to a layered double hydroxide (LDH) material and methods for using the LDH material to catalyse the oxygen evolution reaction (OER) in a water-splitting process. The invention also provides a composition, a catalytic material, an electrode and an electrolyser including the LDH material. In particular, the LDH material includes a metal composite including cobalt, iron, chromium and optionally nickel species interspersed with a hydroxide layer.

The present invention provides an alkaline water electrolysis anode such that even when electric power having a large output fluctuation, such as renewable energy, is used as a power source, the electrolysis performance is unlikely to be deteriorated and excellent catalytic activity is retained stably over a long period of time. The alkaline water electrolysis anode is an alkaline water electrolysis anode 10 provided with an electrically conductive substrate 2 at least a surface of which contains nickel or a nickel base alloy and a catalyst layer 6 disposed on the surface of the electrically conductive substrate 2, the catalyst layer 6 containing a nickel-containing metal oxide having a spinel structure, wherein the nickel-containing metal oxide contains nickel (Ni) and manganese (Mn), and has an atom ratio of Li/Ni/Mn/O of (0.0 to 0.8)/(0.4 to 0.6)/(1.0 to 1.8)/4.0.

The present invention provides a water electrolysis electrode including a catalyst having a three-dimensional nanosheet structure with a low overvoltage and excellent catalytic activity, a method for producing the same, and a water electrolysis device including the same. The water electrolysis electrode according to the present invention includes a catalyst layer, which includes a composite metal oxide and has a three-dimensional nanosheet structure, and an electrode substrate. The method for producing a water electrolysis electrode according to the present invention comprises steps of: immersing an electrode substrate in an electrolyte solution containing metal oxide precursors; electrodepositing composite metal hydroxides by applying a voltage to the electrode substrate; and forming a composite metal oxide by annealing the electrode substrate. The water electrolysis device according to the present invention includes the water electrolysis electrode according to the present invention as an anode.

Provided are: an oxygen catalyst that uses an alkaline aqueous solution as an electrolyte and has high catalytic activity; and an electrode. The oxygen catalyst according to the present invention is an oxygen catalyst in which an alkaline aqueous solution is used as an electrolyte, the oxygen catalyst being characterized by having a pyrochlore oxide structure including bismuth on an A-site and ruthenium on a B-site, and containing manganese as well as bismuth and ruthenium. The electrode according to the present invention is characterized by using the oxygen catalyst according to the present invention.

The present invention provides a water electrolysis method comprising: supplying at least water into an electrolysis cell which includes a solid polymer electrolyte membrane, and an anode and a cathode disposed sandwiching the solid polymer electrolyte membrane therebetween; and providing a potential P between the anode and the cathode to generate oxygen from the anode, wherein an oxidation catalyst containing at least one of first transition metals is present on at least a part of a surface of the anode, and the potential P satisfies P1<P<P2, wherein P1 indicates a lowest potential at which oxygen is generated from the anode, and P2 indicates a lowest potential P2 at which a quantitative index of a dissolved chemical species derived from the oxidation catalyst begins to show potential dependence.

The present invention provides an electrode for electrolysis in which electrolysis performance is hard to deteriorate and excellent catalytic activity is kept stable over a long period of time even when electric power in which there is a large fluctuation in output, such as renewable energy, is used as a power source. The electrode for electrolysis is an electrode 10 for electrolysis provided with an electrically conductive substrate 2 at least the surface of which contains nickel or a nickel-based alloy, an intermediate layer 4 formed on the surface of the electrically conductive substrate 2 and containing a lithium-containing nickel oxide represented by composition formula Li.sub.xNi.sub.2-xO.sub.2 (0.02x0.5), and a catalyst layer 6 of a nickel cobalt spinel oxide, an iridium oxide, or the like, the catalyst layer 6 formed on the surface of the intermediate layer 4.

The present invention provides an electrode for electrolysis in which electrolysis performance is hard to deteriorate and excellent catalytic activity is kept stable over a long period of time even when electric power in which there is a large fluctuation in output, such as renewable energy, is used as a power source. The electrode for electrolysis is an electrode 10 for electrolysis provided with an electrically conductive substrate 2 at least the surface of which contains nickel or a nickel-based alloy, an intermediate layer 4 formed on the surface of the electrically conductive substrate 2 and containing a lithium-containing nickel oxide represented by composition formula Li.sub.xNi.sub.2-xO.sub.2 (0.02x0.5), and a catalyst layer 6 of a nickel cobalt spinel oxide, an iridium oxide, or the like, the catalyst layer 6 formed on the surface of the intermediate layer 4.