Suppressing Mo-Species Leaching in MoO/A-NiS Cathode for Stable Anion Exchange Membrane Water Electrolysis at Industrial-Scale Current Density.

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 MoS/NiS 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 MoS underwent an oxidative dissolution followed by a dynamic equilibrium between dissolution and redeposition of the amorphous MoO during HER. Meanwhile, S-vacancy-rich NiS (A-NiS) is exposed and acts as the real active site for HER. The obtained MoO/A-NiS 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/A-NiS electrode. Remarkably, the device assembled by MoO/A-NiS as the cathode catalyst and NiFe as the anode catalyst demonstrated a high stability of 2500 h at 2 A cm and 40 °C with a small aging rate of 30 µV h.