Cathode electrodes used in chlor-alkali electrolyzers are usually made of carbon steel in diaphragm cells and nickel in membrane cells.
A detailed examination of the cell voltage contributions shows a considerable impact of cathode overvoltage, influenced mainly by the electrode material and the operating current density.
Commercialization of DSA® anodes worldwide and increasing energy prices, provided impetus in “hydrogen evolution” applications to develop materials such as mixed oxides and high surface – high performing nickel based electrodes as cathodes to reduce energy consumption.
Current membrane cells cathodes are characterized by the following technical solutions:
NRG® coating family performances
The new catalyst family (including NRG®-R, NRG®-V, NRG®-S products) is capable of ensuring an HOV (Hydrogen Over Voltage) value of 60 mV (@ 3kA/m², NaOH 32%, 90°C CISEP protocol) with a considerable energy saving if referred to electrodes using Ni-Raney based coatings (HOV of 100 ÷ 120 mV) or simply sandblasted nickel (280 ÷ 350 mV).