High-performance alkaline water electrolysis: a membrane–catalyst–device integrated paradigm

Abstract

Alkaline exchange membrane water electrolysis (AEMWE) is critical for advancing next-generation water electrolysis technologies. Development of cost-effective and durable bifunctional electrocatalysts and chemically robust anion exchange membranes (AEMs), which are the key components for AEMWE, are essential. Herein, we report the rational design of a phosphorus-doped trimetallic oxide heterostructure (PhosTriOx) as a highly active and stable bifunctional catalyst and alkaline stable crosslinked p-methylstyrene-based AEM (Styrion AEM) for alkaline water splitting. The optimized PhosTriO7 catalyst exhibits hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity, requiring overpotentials of 180 mV and 410 mV at 50 mA cm⁻², respectively. The Styrion AEM exhibits an ionic conductivity of 51.5 mS cm⁻¹ at 90 °C, an ion exchange capacity (IEC) of 0.85 meq. g⁻¹, and a water uptake of 23–25%, along with long-term alkaline stability. When integrated into a membrane electrode assembly (MEA), the PhosTriO7–AEM system achieved a current density of 1.6 A cm⁻² at 2.0 V, surpassing that of Pt/C- and RuO_x-based MEAs, and maintained stable operation at 1.82 V at 1 A cm⁻² for 250 h with negligible degradation. This work introduces a new material–membrane–device framework and demonstrates that phosphorus-modulated heterostructures synergized with chemically durable AEMs can compete with or surpass noble-metal benchmarks in durability and system-level performance, paving the way toward scalable and sustainable hydrogen production.