The synergistic effect of Ni–NiMo4N5 heterointerface construction and Fe-doping enables active and durable alkaline water splitting at industrial current density

Abstract

Alkaline anion-exchange membrane water electrolysis (AEMWE) is hailed as a promising approach to green hydrogen production due to its cost-effectiveness and high compatibility with intermittent renewable electricity, yet its practical implementation is hindered by the lack of active and durable bifunctional water-splitting electrocatalysts. Here, we developed a heterogeneous NiFeMo-based catalyst with abundant metal–metal nitride heterostructures towards efficient and durable water electrolysis. The heterostructure not only leads to a smaller work function (Φ) for accelerating the electron transfer process, but also tailors the adsorption–desorption behavior of intermediates due to the modified electronic states. As a result, the optimal NiFeMo-based catalyst significantly improves the water-splitting performance with an ultra-low overpotential of 68 and 228 mV at 100 mA cm⁻² for alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. When assembled in an AEM water electrolyzer, the catalyst achieves a current density of 500 and 1000 mA cm⁻² at a low voltage of 1.620 and 1.753 V, respectively. More importantly, it can stably operate over 1630 hours at 500 mA cm⁻², demonstrating its superior long-term stability. This work not only affords a high-performance bifunctional electrocatalyst for AEMWE, but also provides a multi-faceted structural regulation strategy to tailor the catalytic properties of heterogeneous electrocatalysts.