In various industrial electrolysis processes that use sulfuric acid electrolytic solutions,such as electrolytic extraction of non-ferrous metals represented by zinc production,small and medium-sized precious metal electroplating in the electroplating industry,galvanizing in the large-scale steel industry,electrolytic manufacturing of copper foil for printed circuit boards,electrolytic reduction to produce various organic compounds,etc.,the purpose is cathodic reduction reaction.During electrolysis,oxygen evolution reaction occurs on the anode.Therefore,it is hoped to develop an anode material with low oxygen overpotential and good electrolytic durability.

The best coating for oxygen evolution electrodes in the electrolysis industry is a mixed oxide coating of iridium oxide and tantalum oxide.This type of electrode has low overpotential,long lifespan,and can operate at high anode current densities.It has superior performance but is expensive.

Typical formula of iridium tantalum

(1)TaCI5 is 10.7mg,IrCI3 is 16.0mg,i.e.Ta:Ir=0.67:1(metal mass ratio).The anode potential is initially 1.51V and reaches 1.64V after 6000 hours,with a coating weight loss of 0mg/㎡.

24 pieces of 25px x 25px titanium sheets,coated with the aforementioned solution 15 times.After each drying,heat at 500℃for 10 minutes,and then sinter for 1 hour for the last time.The initial anode potential of the ruthenium titanium coated electrode is 1.48V,which rises to 2.0V after 1000 hours and the anode has been passivated.Measurement conditions for anodic potential:10%sulfuric acid solution,1.2kA/m2,60℃.Same as below.

(2)When the electrode substrate is palladium titanium alloy(w(Pd)=0.15%),TaCl5 is 10.70mg,IrCI3 is 16.0mg,the initial anode potential is 1.51V,and after 6000 hours it is 1.65V.After 2000 hours of operation,the coating quality loss is 0.The results indicate that the titanium palladium alloy substrate electrode has excellent electrocatalytic activity and low passivation rate.

When preparing the coating solution,Ir can be treated with chloroiridic acid,IrCL3;Ta can be tantalum butoxide,Tacl5。Tantalum pentachloride is soluble in 20%hydrochloric acid.TaCl5 will decompose in water,and an anhydrous mixed organic solvent,ethanol isopropanol(1:1),should be used.Chloroiridic acid and butoxide tantalum are soluble in n-butanol.The amount of iridium in the coating is 10g/㎡.