Performance of activated stainless steel and nickel-based anodes in alkaline water electrolyser

Abstract

Four different alloys including SS316, SS304, Inconel718 and Incoloy800 are activated by electro-oxidation at +1.70 V vs. RHE in 7.5 M KOH for 18 h. Their OER activity are evaluated ex-situ using linear sweep voltammetry in 1.0 M KOH in a three-electrode electrochemical cell. X-ray photoelectron microscopy and scanning electron microscopy are used to obtain the surface composition and surface morphology. It is found that the OER activity improves as the Ni content at the surface increases. A Ni mesh along with untreated and activated SS316 meshes were investigated in-situ in 30 wt% KOH at 80 °C in an alkaline electrolyser. The effect of temperature up to 80 °C as well as pressure up to 9 bar are studied on the cell performance. It is observed that the cell with activated SS316 as anode is outperforming those with the Ni and untreated SS316 as anode. Up to 255 h durability tests at constant current of 0.8 A cm−2 at 80 °C and 9 bar shows no degradation in the performance of the cells containing Ni and activated SS316 as anode. SS316 is also activated in-situ at 1.76 A cm−2 for 18 h and 2 bar. The in-situ activation improves the SS316 OER activity.