The invention relates to a particulate catalyst, containing: a support material, an iridium-containing coating which is provided on the support material and which contains iridium oxide, an iridium hydroxide, or an iridium hydroxide oxide, wherein the support material has a BET surface area ranging from 2 m.sup.2/g to 50 m.sup.2/g, and the iridium content of the catalyst satisfies the following condition: (1.505 (g/m.sup.2)BET)/(1+0.0176 (g/m.sup.2)BET)Ir-G(4.012 (g/m.sup.2)BET)/(1+0.0468 (g/m.sup.2)BET), where BET is the BET surface area of the support material, in m.sup.2/g, and Ir-G is the iridium content, in wt. %, of the catalyst.

The invention relates to a particulate catalyst, containing: a support material, an iridium-containing coating which is provided on the support material and which contains iridium oxide, an iridium hydroxide, or an iridium hydroxide oxide, wherein the support material has a BET surface area ranging from 2 m.sup.2/g to 50 m.sup.2/g, and the iridium content of the catalyst satisfies the following condition: (1.505 (g/m.sup.2)BET)/(1+0.0176 (g/m.sup.2)BET)Ir-G(4.012 (g/m.sup.2)BET)/(1+0.0468 (g/m.sup.2)BET), where BET is the BET surface area of the support material, in m.sup.2/g, and Ir-G is the iridium content, in wt. %, of the catalyst.

A water electrolyzer includes an electrochemical cell including an anode and a cathode, an electrolyte solution, a voltage applicator, and a controller. The voltage applicator applies a voltage between the anode and the cathode. The electrochemical cell includes nickel. In the shutdown of the water electrolyzer, the controller causes the voltage applicator to apply the voltage at least when the temperature of the electrolyte solution is equal to or more than a predetermined threshold value.

A water electrolyzer includes an electrochemical cell including an anode and a cathode, an electrolyte solution, a voltage applicator, and a controller. The voltage applicator applies a voltage between the anode and the cathode. The electrochemical cell includes nickel. In the shutdown of the water electrolyzer, the controller causes the voltage applicator to apply the voltage at least when the temperature of the electrolyte solution is equal to or more than a predetermined threshold value.

An electrolyser (F) for generating hydrogen from water, the electrolyser comprising an electrode (102), the electrode (120) comprising nanoparticles selected from Group 1 nanoparticles or alloys or composites or mixtures thereof.

An electrolyser (F) for generating hydrogen from water, the electrolyser comprising an electrode (102), the electrode (120) comprising nanoparticles selected from Group 1 nanoparticles or alloys or composites or mixtures thereof.

The present invention relates to a photo-electrochemical device for production of a gas, liquid or solid using concentrated electromagnetic irradiation. The device comprises a photovoltaic component configured to generate charge carriers from the concentrated electromagnetic irradiation; and an electrochemical component configured to carry out electrolysis of a reactant. The photovoltaic component contacts the electrochemical component at a solid interface to form an integrated photo-electrochemical device; and further includes at least one reactant channel or a plurality of reactant channels extending between the photovoltaic component and the electrochemical component to transfer heat and the reactant from the photovoltaic component to the electrochemical component. The integrated photo-electrochemical device and auxiliary devices (such as concentrator, flow controllers) build a system which can flexibly react to changes in operating condition and guarantee best performance.

An iridium-ruthenium-based oxide anode catalyst for water electrolysis includes a heterostructure within the particles, different phases within the particles being adjacent to each other, and the different phases within the particles consist of iridium and ruthenium, the catalyst is synthesized using metal sulfides (MxS) as precursors, and the catalyst is characterized by the introduction of transition metal elements as dopants.

An iridium-ruthenium-based oxide anode catalyst for water electrolysis includes a heterostructure within the particles, different phases within the particles being adjacent to each other, and the different phases within the particles consist of iridium and ruthenium, the catalyst is synthesized using metal sulfides (MxS) as precursors, and the catalyst is characterized by the introduction of transition metal elements as dopants.

An electrochemical cell includes a metal substrate and a cell body. The metal substrate has: a gas-permeable region in which a plurality of connecting holes are formed; and a non-gas-permeable region surrounding the gas-permeable region in a plan view. The cell body is disposed on the metal substrate. The cell body has: a first electrode layer containing Ni; a second electrode layer; and an electrolyte layer disposed between the first electrode layer and the second electrode layer. The first electrode layer has a first region formed on the gas-permeable region, and a second region formed on the non-gas-permeable region. A mean particle diameter of Ni contained in the second region is smaller than a mean particle diameter of Ni contained in the first region.