Facet-engineered NiMo-MoO2 heterostructure with enhanced built-in electric field for anion exchange membrane water electrolysis at industrial-grade current density

A novel facet-engineered NiMo-MoO 2 catalyst (Fac/NiMo/NF) was synthesized. • Fac/NiMo/NF shows a low overpotential of 119 mV for hydrogen evolution reaction (HER) to reach 1 A cm −2 . • Fac/NiMo/NF delivers a low cell voltage of 2 V at 80 ℃ to reach 5.2 A cm −2 in anion exchange membrane water electrolysis (AEMWE). • Fac/NiMo/NF catalyst demonstrates excellent durability for 2000 h in AEMWE at industrial-grade current density (2 A cm −2 ). Anion exchange membrane water electrolysis (AEMWE) is emerging as a promising technology for green hydrogen production. However, the synthesis of efficient noble metal-free catalysts remains a critical challenge. Herein, we report a heterointerface-enabled NiMo-MoO 2 (−101) catalyst (Fac/NiMo/NF) synthesized via an electrostatic adsorption strategy, in which the MoO 2 component preferentially exposes the (−101) facet instead of the conventional (−111) facet. This facet-selective exposure fundamentally reconstructs the interface configuration and substantially increases work function difference across the NiMo-MoO 2 heterointerface. The resulting strong built-in electric field promotes interfacial charge redistribution and accelerates hydrogen evolution reaction (HER) kinetics. Moreover, the NiMo-MoO 2 (−101) heterointerface promotes water dissociation, thereby accelerating the Volmer step and enhancing the HER activity. Density functional theory calculations further reveal that the NiMo-MoO 2 (−101) possesses optimal hydrogen adsorption, accounting for its superior activity. The AEMWE assembled with Fac/NiMo/NF as the cathode exhibits a current density of 5.2 A cm −2 at 2 V and demonstrates excellent durability for 2000 h at an industrial-grade current density of 2 A cm −2 . This work highlights that integrating facet engineering with heterointerface design offers an effective strategy for developing durable, high-performance self-supported electrodes for practical water electrolysis. Download: Download high-res image (144KB) Download: Download full-size image