The present disclosure relates to a transition metal-doped nickel phosphide nanostructure, a method for preparing the same, and a catalyst for electrochemical water decomposition including the transition metal-doped nickel phosphide nanostructure. More specifically, a transition metal-doped nickel phosphide nanostructure can be prepared by converting a zinc oxide nanostructure grown on a substrate vertically by hydrothermal synthesis to a transition metal-doped nickel oxide nanostructure by cation exchange and then phosphorizing the nickel oxide. The transition metal-doped nickel phosphide nanostructure of the present disclosure is advantageous in that it has superior catalytic activity and conductivity due to large surface area. In addition, when used as a catalyst for water decomposition under an alkaline condition, it has a low overvoltage and can have excellent catalytic activity for hydrogen evolution reaction or oxygen evolution reaction.

The present disclosure relates to a transition metal-doped nickel phosphide nanostructure, a method for preparing the same, and a catalyst for electrochemical water decomposition including the transition metal-doped nickel phosphide nanostructure. More specifically, a transition metal-doped nickel phosphide nanostructure can be prepared by converting a zinc oxide nanostructure grown on a substrate vertically by hydrothermal synthesis to a transition metal-doped nickel oxide nanostructure by cation exchange and then phosphorizing the nickel oxide. The transition metal-doped nickel phosphide nanostructure of the present disclosure is advantageous in that it has superior catalytic activity and conductivity due to large surface area. In addition, when used as a catalyst for water decomposition under an alkaline condition, it has a low overvoltage and can have excellent catalytic activity for hydrogen evolution reaction or oxygen evolution reaction.

A coral reef-like nickel phosphide-tungsten oxide nanocomposite is disclosed. The coral reef-like nickel phosphide-tungsten oxide nanocomposite has a structure in which algae-like transition metal-doped nickel phosphide nanosheets are deposited on coral-like tungsten oxide nanostructures grown vertically on a substrate. This structure allows the coral reef-like nickel phosphide-tungsten oxide nanocomposite to have a large surface area, which leads to a significant increase in the number of catalytic active sites, and ensures high conductivity and electrochemical stability of the coral reef-like nickel phosphide-tungsten oxide nanocomposite. Due to these advantages, the coral reef-like nickel phosphide-tungsten oxide nanocomposite has a low overpotential and superior hydrogen evolution reaction or oxygen evolution reaction efficiency when applied to a water splitting catalyst under alkaline conditions. Also disclosed are a method for preparing the coral reef-like nickel phosphide-tungsten oxide nanocomposite and a catalyst for electrochemical water splitting including the coral reef-like nickel phosphide-tungsten oxide nanocomposite.

A coral reef-like nickel phosphide-tungsten oxide nanocomposite is disclosed. The coral reef-like nickel phosphide-tungsten oxide nanocomposite has a structure in which algae-like transition metal-doped nickel phosphide nanosheets are deposited on coral-like tungsten oxide nanostructures grown vertically on a substrate. This structure allows the coral reef-like nickel phosphide-tungsten oxide nanocomposite to have a large surface area, which leads to a significant increase in the number of catalytic active sites, and ensures high conductivity and electrochemical stability of the coral reef-like nickel phosphide-tungsten oxide nanocomposite. Due to these advantages, the coral reef-like nickel phosphide-tungsten oxide nanocomposite has a low overpotential and superior hydrogen evolution reaction or oxygen evolution reaction efficiency when applied to a water splitting catalyst under alkaline conditions. Also disclosed are a method for preparing the coral reef-like nickel phosphide-tungsten oxide nanocomposite and a catalyst for electrochemical water splitting including the coral reef-like nickel phosphide-tungsten oxide nanocomposite.

A flow-through electrolysis cell includes a hierarchical nanoporous metal cathode. A method of reducing CO.sub.2 includes flowing the CO.sub.2 through the hierarchical nanoporous metal cathode of the flow-through electrolysis cell.

A flow-through electrolysis cell includes a hierarchical nanoporous metal cathode. A method of reducing CO.sub.2 includes flowing the CO.sub.2 through the hierarchical nanoporous metal cathode of the flow-through electrolysis cell.

An alkaline electrolyser device for hydrogen production includes a first and a second electric charge battery substantially identical. Each electric charge battery has a first electrode of copper, silver or their alloys, coated with zinc, a second electrode with a ferrous catalyst, and an alkaline aqueous solution in which the first and second electrodes are immersed. An output opening placed in correspondence of the second electrode is suitable to allow the escape from the battery of gases which develop in correspondence of the second electrode. The batteries are short-circuited with an electric power supply member placed between the first or the second electrodes, with a predefined polarity such that the voltage across the electrodes is higher than 1.3 V. In this configuration, the first battery undergoes a discharging process producing hydrogen gas, whilst, contextually, the second battery undergoes a charging process generating oxygen gas. When the discharge cycle of the first battery is completed, the polarity of the electric power supply is inverted, so that the second battery begins to discharge producing hydrogen gas and, at the same time, the first battery recharges producing oxygen gas. The polarity inversion is repeated cyclically so that oxygen and hydrogen are produced alternately in the two batteries.

An alkaline electrolyser device for hydrogen production includes a first and a second electric charge battery substantially identical. Each electric charge battery has a first electrode of copper, silver or their alloys, coated with zinc, a second electrode with a ferrous catalyst, and an alkaline aqueous solution in which the first and second electrodes are immersed. An output opening placed in correspondence of the second electrode is suitable to allow the escape from the battery of gases which develop in correspondence of the second electrode. The batteries are short-circuited with an electric power supply member placed between the first or the second electrodes, with a predefined polarity such that the voltage across the electrodes is higher than 1.3 V. In this configuration, the first battery undergoes a discharging process producing hydrogen gas, whilst, contextually, the second battery undergoes a charging process generating oxygen gas. When the discharge cycle of the first battery is completed, the polarity of the electric power supply is inverted, so that the second battery begins to discharge producing hydrogen gas and, at the same time, the first battery recharges producing oxygen gas. The polarity inversion is repeated cyclically so that oxygen and hydrogen are produced alternately in the two batteries.

A catalyst comprising a porous electrically conductive substrate (such as a foam, carbon fibre paper and carbon fibre cloth) and a porous metallic composite of amorphous NiMoP coating at least a portion of the surface or multiple surfaces of the substrate. The composite preferably forms a continuous layer which coats the surfaces and pores of the substrate. Also methods for preparing and using the catalyst, for example in electrolytic water splitting.

A catalyst comprising a porous electrically conductive substrate (such as a foam, carbon fibre paper and carbon fibre cloth) and a porous metallic composite of amorphous NiMoP coating at least a portion of the surface or multiple surfaces of the substrate. The composite preferably forms a continuous layer which coats the surfaces and pores of the substrate. Also methods for preparing and using the catalyst, for example in electrolytic water splitting.