A method for the manufacture of an electrode for use in electrochemical processes, which comprises forming on the surface of a support of film-forming metal of the group of titanium, zirconium, niobium, tantalum and tungsten or an alloy principally of one of these metals, a layer of an operative electrode material, applying over the said layer a coating comprising a thermally decomposable organo-compound of a film-forming metal of the group of alkoxides and alkoxy-halides of titanium, zirconium, niobium, tantalum and tungsten wherein the halogen is chlorine, bromine or fluorine in a liquid vehicle and heating the coating to convert the organo-compound of the film-forming metal to an oxide.

Electrodes for electrochemical processes

An electrode is provided which resists passivation over long periods of time and hence which is especially well suited for use as an oxygen anode. The electrode comprises 1) an electrically conductive supporting substrate, 2) an intermediate, electrically conductive, barrier layer and 3) an electrocatalytically active, solid solution-type, outer coating. The barrier layer is selected from the group consisting of platinum-iridium alloys and oxides of cobalt, manganese, palladium, lead and platinum.

Non-passivating barrier layer electrodes

Novel electrodes consisting essentially of a valve metal base or other electrically conductive material which is corrosion-resistant to the anodic conditions having on at least a portion of its outer surface an electrocatalytic coating of β-manganese dioxide chemi-deposited by thermal decomposition of an alcoholic solution of manganese nitrate which are useful in electrolysis processes in which oxygen is formed at the anode such as electrowinning of metals from sulfuric acid solution or in the electrolytic production of perchlorates. Also included are electrodes where the β-manganese dioxide coating is activated by doping with up to 5% by weight of at least one metal of the groups IB, IIB, IVA, VA, VB, VIB, VIIB, and VIII of the Periodic Table excluding the platinum group metals, gold and silver or activated by irradiation of the β-manganese dioxide coating and/or stabilized by the addition of up to 20% by weight of silicon dioxide, tin dioxide or β-lead dioxide as a mechanical stabilizer for the coating.

Manganese dioxide electrodes

Porous electrode bodies are effectively provided with efficient internal surface deposits of manganese oxide(s) catalyst formations by decomposition, under an atmosphere that can either be oxidizing, reducing or inert in nature, at an elevated temperature of a pre-applied anionic manganese salt reagent (notably manganese nitrate but also certain carboxylic acid salts of manganese, etc.) in order to chemically decompose the reagent to advantageous manganese oxide forms within the body pores. Exposure to a reducing environment after catalyst deposition ameliorates the provided catalyst structure by rendering therein more electrocatalytically active variations of the emplaced manganese oxides. Highly reliable and satisfactory electrode products particularly well suited for use as depolarized cathodes, especially in chlor-alkali cells, are obtained from the treatment.

Oxygen electrode preparation

Disclosed is an electrode for use in electrochemical processes especially electrowinning processes wherein a metal substrate made of a valve metal such as titanium carries a semiconducting intermediate coating consisting of a combination of tin and antimony oxides laid down upon the valve metal substrate in a series of layers and a top coating consisting of manganese dioxide applied in a series of layers.

Manganese dioxide electrode

An insoluble anode suitable for use in electrolysis and a method for its production are provided. The anode comprises three components which are: A. A BASE SUBSTRATE TREATED BY SANDBLASTING, SAID SUBSTRATE BEING SELECTED FROM THE GROUP CONSISTING OF TITANIUM, ZIRCONIUM AND TANTALUM OR ALLOYS THEREOF; B. A THIN METAL LAYER FORMED ON SAID SUBSTRATE, SAID THIN METAL LAYER BEING SELECTED FROM THE GROUP CONSISTING OF PLATINUM, PALLADIUM AND RHODIUM OR ALLOYS THEREOF; AND C. AN OUTERMOST LAYER OF MANGANESE DIOXIDE ELECTROPLATED ON SAID THIN METAL LAYER IN AN AQUEOUS SOLUTION OF MANGANESE SULFATE CONTAINING ABOUT 10 TO ABOUT 30 GRAMS/LITER OF FREE SULFURIC ACID AT A CURRENT DENSITY OF ABOUT 0.015 TO ABOUT 0.007 A./dm.2. The anode is produced by sandblasting a base substrate metal of titanium or its alloy to form minute indentations on the surface, electroplating on said base substrate metal a thin layer of platinum, and electrodepositing a layer of manganese dioxide on said thin layer in an aqueous solution of manganese sulfate containing 10-30 g./l. of free sulfuric acid at a current density of 0.015-0.007 A./dm.2.

Kazuva Ohsawa Yokohama

Papers

Insoluble anode for electrolysis and a method for its production