Electrodes suitable for use for electrolytic purposes, for example for the electrolysis of aqueous alkali metal chloride solutions, are disclosed. The electrodes of this invention have an electroconductive substrate with an electro-conductive outer surface containing a spinel thereon, and an intermediate electroconductive layer between the electro-conductive spinel surface and the substrate which intermediate layer contains an oxycompound of a second transition series platinum group metal (ruthenium, rhodium, palladium).
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application Ser. No. 86,062, now abandoned filed Nov. 2, 1970, by Aleksandrs Martinsons for "Anode for the Electrolysis of Brines and Process for Making Same".
The invention relates to a process for the electrolytic production of hydrogen in an alkaline medium. The process consists in using a cathode, the active surface of which essentially consists of an oxide compound of the spinel type. The process is suitable, in particular, for the electrolysis of aqueous solutions of sodium chloride in cells with a permeable diaphragm.
Disclosed is a method of electrolyzing an aqueous alkali metal chloride, which method comprises passing an electrolytic current from an anode of an electrolytic cell through an alkali metal chloride electrolyte to a cathode of the cell, evolving chlorine at the anode and hydrogen at the cathode. The method is characterized by the use of a cathode having a layer of an oxy-compound of a platinum group metal and an alkaline earth metal on an electroconductive cathode substrate.
A titanium or niobium electrode substrate (which may be copper or steel cored) having on its surface a painted and fired anodically active layer for example of a platinum group metal, there being an interlayer of tantalum or an alloy containing more than 50% tantalum in metallic form between the anodically active layer and the substrate. The tantalum metal gives enhanced corrosion resistance and acid undermining resistance to titanium substrates and eases the manufacture of painted and fired niobium substrate electrodes. The electrode may be an elongate rod having longitudinally extending protuberances along the length of the rod and around the circumference, the spacing and height of the protuberances being such that a straight line connecting the peaks of two adjacent protuberances does not intersect with the body of the electrode so that the protuberances protect the anodically active coating from damage during installation and operation of the electrode.
Thin films of isotropically conductive material are formed from Sr.sub.1-x Ca.sub.x RuO.sub.3. This material is easily deposited as a thin film by methods such as 90.degree. off-axis sputtering and laser ablation. The materials are epitaxially deposited on a wide variety of substrates and allow overlying epitaxial growth of an equally large number of significant oxides such as superconducting oxides, dielectric, and ferroelectric materials.
A metal electrode with an active cover layer for electrochemical purposes which cover layer includes metal platinates, metal palladates, or the like, and metal palladates and comprises, as embedding substances compounds of the type Ba (M.sub.x Ti.sub.1.sub.-x)O.sub.3 where M is a platinum metal. The latter may be used alone or in combination with other additives and does not impair on the one hand the effectiveness of the active materials and is on the other hand, when exposed to an electrolytic bath, location in chemically resistant without showing complete inactivity and, thus, increase the current yield of the anode.
