Suppressing Mo-Species Leaching in MoO_x/A-Ni₃S₂ Cathode for Stable Anion Exchange Membrane Water Electrolysis at...

The development of non-noble metal-based hydrogen evolving reaction (HER) electrocatalysts operating under high current density plays a critical role in the large-scale application of anion exchange membrane water electrolysis (AEM-WE). Herein, a porous and hybrid MoS₂/Ni₃S₂ is synthesized on nickel foam (NF) via a one-step hydrothermal method and studied its reconstruction process during alkaline HER conditions. Experimental results indicated that the MoS₂ underwent an oxidative dissolution followed by a dynamic equilibrium between dissolution and redeposition of the amorphous MoO_x during HER. Meanwhile, S-vacancy-rich Ni₃S₂ (A-Ni₃S₂) is exposed and acts as the real active site for HER. The obtained MoO_x/A-Ni₃S₂ catalyst exhibited high catalytic performance in three-electrode systems and single-cell AEM-WE. Finally, for a long-term durability test in the AEM electrolyzer, a dry cathode method is applied to suppress the Mo species leaching from the MoO_x/A-Ni₃S₂ electrode. Remarkably, the device assembled by MoO_x/A-Ni₃S₂ as the cathode catalyst and NiFe as the anode catalyst demonstrated a high stability of 2500 h at 2 A cm^-2 and 40 °C with a small aging rate of 30 µV h^-1.