High-load durable anode for oxygen generation and manufacturing method for the same

Abstract

The present invention aims to provide a high-load durable anode for oxygen generation and a manufacturing method for the same used for industrial electrolyses including manufacturing of electrolytic metal foils such as electrolytic copper foil, aluminum liquid contact and continuously electrogalvanized steel plate, and metal extraction, having superior durability under high-load electrolysis conditions. The present invention features an anode for oxygen generation and a manufacturing method for the same comprising a conductive metal substrate and a catalyst layer containing iridium oxide formed on the conductive metal substrate wherein the amount of coating of iridium per time for the catalyst layer is 2 g / m2 or more, the coating is baked in a relatively high temperature region of 430 degrees Celsius-480 degrees Celsius to form the catalyst layer containing amorphous iridium oxide and the catalyst layer containing the amorphous iridium oxide is post-baked in a further high temperature region of 520 degrees Celsius-600 degrees Celsius to crystallize almost all amount of iridium oxide in the catalyst layer.

Description

TECHNICAL FIELD[0001]The present invention relates to an anode for oxygen generation used for various industrial electrolyses and a manufacturing method for the same; more in detail, it relates to a high-load durable anode for oxygen generation and a manufacturing method for the same used for industrial electrolyses including manufacturing of electrolytic metal foils such as electrolytic copper foil, aluminum liquid contact, and continuously electrogalvanized steel plate, and metal extraction, having superior durability under high-load electrolysis conditions.BACKGROUND ART[0002]In industrial electrolyses including manufacturing of electrolytic copper foil, aluminum liquid contact, continuously electrogalvanized steel plate and metal extraction, oxygen generation is involved at the anode. For this reason, the anode which is coated chiefly with iridium oxide having durability to oxygen generation, as electrode catalyst, on the titanium metal substrate has been widely applied. General...

AI Technical Summary

Benefits of technology

The present invention relates to a method of forming an electrode catalyst layer containing iridium oxide. The method includes coating the iridium oxide onto the electrode and conducting a two-stage baking process at high temperatures to form the catalyst layer. This process results in the formation of a small crystallite diameter of iridium oxide, which increases the effective surface area of the catalyst layer and decreases the oxygen generation overvoltage. This results in the reduction of PbO2 attachment and covering on the electrode, improves electrode durability, and provides special performance characteristics to products. The amount of coating of iridium oxide is controlled to achieve improved quality and performance of the electrode.

Problems solved by technology

Under the electrolysis at such a high current density, the electrode catalyst layer is highly loaded and electric current tends to be concentrated there, causing rapid consumption of the electrode catalyst layer.

Use of these substrates, however, involves undesirable extra processing costs.

Furthermore, actual current density decreased by physically increased surface area of the substrate does not improve the electric current concentration at the electrode catalyst layer, resulting in little suppression effect on catalyst consumption.

In the thermolysis formation method of the electrode catalyst layer by repeating coating and baking, if the amount of coating iridium per time is increased, it is simply considered that the formed catalyst layer is soft and fluffy; but by this method only, increase in the effective surface area of the catalyst layer of the electrode is limited and improvements in consumption of the catalyst layer under high-load conditions and in durability could not be observed clearly.

Since the electrode is baked at a temperature of 650 degrees Celsius or more, the metal substrate, such as of titanium causes interfacial corrosion, and becomes poor conductor, causing oxygen overvoltage to increase to an unserviceable degree as electrode.

Moreover, the crystallite diameter of iridium oxide in the catalyst layer enlarges, resulting in decreased effective surface area of the catalyst layer, leading to a poor catalytic activity.

This electrode, however, features amorphous iridium oxide, and is insufficient in electrode durability.

The electrode disclosed by PTL 3 is insufficient in electrode durability because the upper layer of the catalyst layer is amorphous iridium oxide.

Moreover, crystalline iridium oxide exists only in the lower layer, not uniformly distributed over the entire catalyst layer, resulting in insufficient electrode durability.

However, it is thought that electrode durability of these two electrodes is not enough because they contain a large amount of amorphous iridium oxide, as prerequisite.

Under the electrolysis at such a high current density, the electrode catalyst layer is highly loaded and electric current tends to be concentrated there, causing rapid consumption of the electrode catalyst layer.

Moreover, organic substance or impurity elements added for stabilizing product quality cause various electrochemical and chemical reactions, the concentration of hydrogen ion increases in concomitant with the oxygen generation reaction, lowering the pH value, and consumption of electrode catalyst is further expedited.

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