A cobalt catalyst and a preparation method thereof are provided. The cobalt catalyst includes a carrier and a catalytically active substance; the carrier is a cobalt-based substrate material; the catalytically active substance is grown on the surface of the carrier, and the catalytically active substance has a morphology of hydrangea-shaped nanospheres. The cobalt catalyst is an autogenously grown monolithic nanosphere catalyst with a three-dimensional structure assembled by nano-sheets on the catalyst surface. The cobalt catalyst has a high specific surface area and can fully expose the catalytically active sites to enhance the catalytic efficiency. Compared to a nanowire catalyst, the cobalt catalyst has better self-supporting properties, and the active components are not easily aggregated nor fall off during a use process. Therefore, the cobalt catalyst has a longer service life.

A cobalt catalyst and a preparation method thereof are provided. The cobalt catalyst includes a carrier and a catalytically active substance; the carrier is a cobalt-based substrate material; the catalytically active substance is grown on the surface of the carrier, and the catalytically active substance has a morphology of hydrangea-shaped nanospheres. The cobalt catalyst is an autogenously grown monolithic nanosphere catalyst with a three-dimensional structure assembled by nano-sheets on the catalyst surface. The cobalt catalyst has a high specific surface area and can fully expose the catalytically active sites to enhance the catalytic efficiency. Compared to a nanowire catalyst, the cobalt catalyst has better self-supporting properties, and the active components are not easily aggregated nor fall off during a use process. Therefore, the cobalt catalyst has a longer service life.

An aspect of the present disclosure provides time and energy-efficient synthesis of catalysts for water electrolysis. An exemplary synthesis method includes dissolving amounts of Fe(NO.sub.3).sub.3.9H.sub.2O and Na.sub.2S.sub.2O.sub.3.5H.sub.2O in deionized water at ambient temperature to form a solution, placing Ni foam into the solution where the Ni foam serves as a substrate and a Ni source for growth of sulfur-doped (Ni,Fe)OOH (S—(Ni,Fe)OOH) catalysts, leaving the Ni foam in the solution at ambient temperature for a duration between one minute and five minutes to provide a treated foam where the S—(Ni,Fe)OOH catalysts grow on the substrate during the duration, and removing the treated foam from the solution after the duration.

An aspect of the present disclosure provides time and energy-efficient synthesis of catalysts for water electrolysis. An exemplary synthesis method includes dissolving amounts of Fe(NO.sub.3).sub.3.9H.sub.2O and Na.sub.2S.sub.2O.sub.3.5H.sub.2O in deionized water at ambient temperature to form a solution, placing Ni foam into the solution where the Ni foam serves as a substrate and a Ni source for growth of sulfur-doped (Ni,Fe)OOH (S—(Ni,Fe)OOH) catalysts, leaving the Ni foam in the solution at ambient temperature for a duration between one minute and five minutes to provide a treated foam where the S—(Ni,Fe)OOH catalysts grow on the substrate during the duration, and removing the treated foam from the solution after the duration.

Provided is a water electrolysis cell capable of suppressing a deterioration in performance even when a microporous layer is provided. A water electrolysis cell includes a solid polymer electrolyte membrane, a catalyst layer, a microporous layer, and a gas diffusion layer. The microporous layer includes a carrier made of an oxide containing at least one element selected from Ti, Mn, Co, Mo, Ru, W, Nb, and Ta, and a conductive material supported on the carrier.

Provided is a water electrolysis cell capable of suppressing a deterioration in performance even when a microporous layer is provided. A water electrolysis cell includes a solid polymer electrolyte membrane, a catalyst layer, a microporous layer, and a gas diffusion layer. The microporous layer includes a carrier made of an oxide containing at least one element selected from Ti, Mn, Co, Mo, Ru, W, Nb, and Ta, and a conductive material supported on the carrier.

A method for ambient-temperature synthesis of a catalyst for water electrolysis by dissolving an amount of an Fe.sup.2+ source and optionally an amount of a salt of another divalent cation in deionized water at ambient temperature to form a solution, placing nickel (Ni) foam into the solution, whereby the Ni foam serves as a substrate and/or a Ni source for growth of the catalyst, leaving the Ni foam in the solution at ambient temperature for a time duration in a range of from about 0.5 hour to about 4 hours to provide a treated foam, during which time duration, the catalyst is grown on the substrate, and removing the treated foam from the solution after the time duration, wherein the treated foam comprises the catalyst grown thereon.

A method for ambient-temperature synthesis of a catalyst for water electrolysis by dissolving an amount of an Fe.sup.2+ source and optionally an amount of a salt of another divalent cation in deionized water at ambient temperature to form a solution, placing nickel (Ni) foam into the solution, whereby the Ni foam serves as a substrate and/or a Ni source for growth of the catalyst, leaving the Ni foam in the solution at ambient temperature for a time duration in a range of from about 0.5 hour to about 4 hours to provide a treated foam, during which time duration, the catalyst is grown on the substrate, and removing the treated foam from the solution after the time duration, wherein the treated foam comprises the catalyst grown thereon.

The present invention realizes industrially excellent effects such that when electric power having a large output fluctuation, such as renewable energy, is used as a power source, electrolysis performance is unlikely to be deteriorated and excellent catalytic activity is retained stably over a longer period of time, and in addition, the present invention provides a technique that enables forming a catalyst layer of an oxygen generation anode, which gives such excellent effects, with a more versatile materials and by a simple electrolysis method. Provided are an alkaline water electrolysis method including supplying an electrolyte obtained by dispersing a catalyst containing a hybrid nickel-iron hydroxide nanosheet (NiFe-ns) being a composite of a metal hydroxide and an organic substance to an anode chamber and a cathode chamber, and using the electrolyte for electrolysis in each chamber in common, an alkaline water electrolysis method including supplying an electrolyte obtained by dispersing a catalyst containing the NiFe-ns to an anode chamber and a cathode chamber, and performing electrolytic deposition of the NiFe-ns in the electrolytic cell during operation to electrolytically deposit the NiFe-ns on a surface of an electrically conductive substrate having a catalyst layer formed on a surface of an oxygen generation anode, thereby recovering and improving electrolysis performance, and an alkaline water electrolysis anode.

The present invention realizes industrially excellent effects such that when electric power having a large output fluctuation, such as renewable energy, is used as a power source, electrolysis performance is unlikely to be deteriorated and excellent catalytic activity is retained stably over a longer period of time, and in addition, the present invention provides a technique that enables forming a catalyst layer of an oxygen generation anode, which gives such excellent effects, with a more versatile materials and by a simple electrolysis method. Provided are an alkaline water electrolysis method including supplying an electrolyte obtained by dispersing a catalyst containing a hybrid nickel-iron hydroxide nanosheet (NiFe-ns) being a composite of a metal hydroxide and an organic substance to an anode chamber and a cathode chamber, and using the electrolyte for electrolysis in each chamber in common, an alkaline water electrolysis method including supplying an electrolyte obtained by dispersing a catalyst containing the NiFe-ns to an anode chamber and a cathode chamber, and performing electrolytic deposition of the NiFe-ns in the electrolytic cell during operation to electrolytically deposit the NiFe-ns on a surface of an electrically conductive substrate having a catalyst layer formed on a surface of an oxygen generation anode, thereby recovering and improving electrolysis performance, and an alkaline water electrolysis anode.