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US 5,395,422 AGranted
Process of preparing nanocrystalline powders of an electroactive alloy
AssigneeHydro-Quebec
InventorsRobert Schulz, Jean-Yves Huot, Michel Trudeau
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AssigneeHydro-Quebec
InventorsRobert Schulz, Jean-Yves Huot, Michel Trudeau
Estimating the term…
There are described powders comprising agglomerated nanocrystals of an electroactive alloy and oxygen. The main component of the alloy can be of nickel, cobalt, iron or mixtures thereof while the alloying element is one or more transition metals such as Mo, W, V, the alloy also including oxygen. Preferably the nanocrystals will be made of an alloy of nickel, molybdenum and oxygen. An electrode which is used by compacting the powders is also disclosed. Also disclosed, is a process for producing the powders by providing particles of nickel, cobalt and iron or oxides thereof with particles of at least one transition metal, (Mo, W, V) or oxides thereof and subjecting the particles to high energy mechanical alloying such as ball milling under conditions which include oxygen and for a sufficient period of time to produce a nanocrystalline alloy. Electrodes produced from these powders have an electrocatalytic activity for the hydrogen evolution which is comparable or higher than the electrodes which are presently used in the electrochemical industry. Moreover, these materials present an excellent chemical, electrochemical and mechanical stability. When use as a cathode the powders are useful in water electrolyzers, in chlor-alkali or the like cells.
A process for producing powders suitable for preparing electrodes having electrocatalytic properties enabling said electrodes to produce hydrogen in water-electrolyzers, chlor-alkali cells or chlorate-cells, said process comprising providing a mixture of particles of at least one first component selected from the group consisting of nickel, cobalt and iron or oxides thereof, and of at least one second component from Mo, W and V or oxides thereof, at least when no oxides are present in said mixture, placing said mixture in an atmosphere containing oxygen, and essentially subjecting said particles to high energy mechanical alloying for at least ten hours to produce nanocrystalline alloys of said components containing at least 1 wt % oxygen, which are suitable for preparing said electrodes.
In a process for producing chlorates by electrolysis, the improvement which comprises carrying out said electrolysis in an electrolytic cell having a cathode comprising powders comprising agglomerated nanocrystals of a main alloy containing at least one first element selected from the group consisting of nickel, cobalt and iron, and at least one second element selected from molybdenum, tungsten and vanadium, and at least 1 wt % oxygen, said powders being pressed to form an electrode, and are consolidated on a support by electro-codeposition, rolling, painting or spraying techniques to constitute an electrode.
Dependencies are inferred from the claim text.