Interfacial electron transfer-driven activity enhancements of carbide/alloy heterostructured catalysts toward water electrolysis for high-performance anion exchange membrane water electrolysis

Abstract

Designing highly efficient and durable electrocatalysts remains a key challenge for practical alkaline water electrolysis. Here, rationally designed carbide/alloy heterostructured catalysts, Mo₂C/NiMo for the hydrogen evolution reaction (HER) and Mo₂C/FeNiMo for the oxygen evolution reaction (OER), were developed for activity enhancement driven by interfacial electron transfer to enable anion exchange membrane water electrolysis (AEMWE) with extraordinary performances. Mo₂C/NiMo and Mo₂C/FeNiMo achieved ultralow overpotentials of 169 and 303 mV, respectively at 500 mA cm⁻². The Mo₂C//NiMo@NF//PiperION//Mo₂C//FeNiMo@NF based AEMWE delivered an exceptionally high current density of 2.645 A cm⁻² at 2.0 V, along with an insignificant 2.0% decay after 50 h of operation at a commercially relevant current density of 0.5 A cm⁻², underscoring its outstanding catalytic efficiency and durability. In the two carbide/alloy heterostructured catalysts, electrons flow from the alloy domain to the carbide domain, triggering interfacial synergy. The interfacial synergy promotes efficient coupling of water dissociation and H₂ desorption along the Volmer–Heyrovsky route to boost the HER activities of Mo₂C/NiMo, and creates more electropositive Fe and Ni sites for favorable formation of active high-valent intermediates to realize high OER activities of Mo₂C/FeNiMo. This work highlights the great promise of carbide/alloy heterostructures as advanced electrocatalysts for scalable and efficient alkaline water electrolysis.