What is the Best Electrode Material for Ozone Production?

What is the Best Electrode Material for Ozone Production?
 
Electrolysis was the first production method for ozone, but for most applications ozone is now produced by corona discharge. By using anodes with a high oxygen overvoltage, a high current density, and a low water temperature it is possible to produce ozone directly from the water according to Equation:
3H2O → O3 + 6e– + 6H+

The disadvantages of electrolytic production include too low a current efficiency, complicated production systems, unstable electrode materials (such as lead oxide (PbO2) anodes), and/or difficult-to-handle electrolytes. Electrolytic production may become more attractive using a new simple electrode assembly of a ‘sandwich’ configuration: diamond anode/solid polymer electrolyte (SPE)/cathode sandwich.

By using such a diamond-SPE sandwich or similar device in deionized water, ozone can be produced with high current efficiency (up to 47%). These devices can easily be inserted into water pipes or reservoirs to produce the required quantity of ozone directly from the water to be treated. The Nafion® ion exchange membrane may be employed as the SPE material.

 If the doped diamond anode is replaced by a Pt- or IrO2-coated anode, a much lower ozone production rate is measured. On the other hand, if Pt is used as the cathode material, the overvoltage for hydrogen production can be lowered, minimizing the cell voltage. For the electrochemical disinfection of ultrapure water or other waters with very low conductivity (such as rainwater), electrochemical ozone production with diamond-SPE sandwich electrodes is the method of choice.