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.

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.

The invention concerns a process for the electrochemical production of formate. The process is performed in an electrochemical cell comprising a cathode compartment containing a cathode, an anode compartment containing a nickel-based anode and an ion exchange membrane separating the anode compartment from the cathode compartment. The process comprises the following steps: (a) feeding an anolyte comprising at least one polyol to the anode compartment; (b) feeding a catholyte comprising CO.sub.2 to the cathode compartment; (c) and applying a voltage difference between the cathode and the anode such that at the cathode CO.sub.2 is reduced to formate and at the anode the at least one polyol is oxidized to formate.

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 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.

Disclosed herein are methods and systems that relate to electrochemically producing hydrogen gas by maintaining a steady-state pH differential of greater than 1 between an anode electrolyte and a cathode electrolyte in a hydrogen-gas generating electrochemical cell.

A device for producing hydrogen by water electrolysis, which includes a protective shell and an electrolytic bath provided in the protective shell, and a power supply cable and a pipeline are provided on the electrolytic bath, and both the power supply cable and the pipeline are coupled to the outside of the protective shell. In the device for producing hydrogen by water electrolysis provided by the present application, a protective shell is provided outside the electrolytic bath to avoid the exposed design of the electrolytic bath, that is, the device for producing hydrogen by water electrolysis can thus be installed indoors or outdoors, thereby improving the versatility of the device for producing hydrogen by water electrolysis.

A device for producing hydrogen by water electrolysis, which includes a protective shell and an electrolytic bath provided in the protective shell, and a power supply cable and a pipeline are provided on the electrolytic bath, and both the power supply cable and the pipeline are coupled to the outside of the protective shell. In the device for producing hydrogen by water electrolysis provided by the present application, a protective shell is provided outside the electrolytic bath to avoid the exposed design of the electrolytic bath, that is, the device for producing hydrogen by water electrolysis can thus be installed indoors or outdoors, thereby improving the versatility of the device for producing hydrogen by water electrolysis.