Alloying-Boosted PtNi Cathode Promotes OH- Desorption for Enhanced Iron Tolerance in Industrial Alkaline Water Electrolysis

Platinum-based noble metal cathodes employed in industrial alkaline water electrolyzers are highly susceptible to iron impurities present in the alkaline electrolyte, which significantly shorten their operational lifetime. In this work, a facile alloying strategy was developed to construct ternary PtNiCu and PtNiFe electrodes using nickel foam (NF) as the substrate. The incorporation of Cu or Fe as a third metal effectively modulates the electronic structure of Ni sites in the PtNi alloy, inducing a downward shift of the Ni d-band center. This electronic regulation weakens OH- adsorption on Ni sites, thereby suppressing surface hydroxyl accumulation and reducing the nucleation and deposition of iron species in the form of iron oxides. As a result, the stability of the electrodes in the Fe-containing alkaline electrolyte is markedly enhanced. Both ternary alloys exhibit substantially improved durability compared with pristine PtNi under Fe-contaminated conditions. Among them, PtNiCu delivers a lower initial overpotential, whereas PtNiFe demonstrates superior long-term stability. After 12 h of hydrogen evolution reaction operation at 400 mA cm−2 in a 6.0 M KOH electrolyte containing 5 ppm FeCl2 at 80 °C, the overpotentials of PtNiCu and PtNiFe are reduced by 152 and 151 mV, respectively, relative to PtNi. Moreover, the amount of deposited iron oxides on PtNiCu and PtNiFe is only about 50 and 25% of that on PtNi, respectively, confirming their much stronger resistance to Fe-induced deactivation.