One-pot synthesized Li, V co-doped Ni3S2 nanorod arrays as a bifunctional electrocatalyst for industrialization-facile hydrogen production via alkaline exchange membrane water electrolysis

The design of a bifunctional electrocatalyst with excellent performance in water electrolysis under high current densities for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with non-noble metals-based catalysts has been challenging. A novel bifunctional electrocatalyst constituted as the lithium and vanadium (Li, V) co-doped nickel sulfide (Ni3S2) nanorod arrays (LVN-0.1) is designed and investigated to take this challenge. The overall water splitting (OWS) electrolyzer constructed with our LVN-0.1 catalyst exhibited low cell voltages of 1.44 and 1.95 V to achieve 10 and 1000 mA/cm2, respectively, with excellent durability, which is almost the best Ni3S2-based electrocatalyst reported to date. The practical scale-up LVN-0.1 stack cell of 2 x 2 cm2 required 1.92 and 2.02 V to achieve high current densities at the industrial level at 500 and 1000 mA/cm2, respectively. Notably, our alkaline stack cell achieved a cell-efficiency of 61.9% and cell stability for 200 h at 1000 mA/cm2, while commercial alkaline cells have kept operating below 500 mA/cm2 to avoid the drop-off of binder-coated electrocatalysts. This study provides a facile way to design bifunctional electrocatalysts for realizing high efficient and stable hydrogen production by alkaline water splitting.