Synergistic Surface and Interface Regulation of Ultralow-Pt-Loading Cathodes for Low-Alkalinity AEMWEs

Anion exchange membrane water electrolysis (AEMWE) requires operating under low-alkalinity conditions with minimal platinum (Pt) loading for practical and cost-effective deployment. However, these conditions impose severe cathodic penalties by aggravating interfacial transport limitations and intensifying the kinetic burden on sparse active sites. Here, we achieve synergistic surface and interface regulation of ultralow-Pt-loading cathodes by interfacing Pt/C with a crystalline melamine-isophthalic acid hydrogen-bonded organic framework (MA-IPA HOF). This fixed framework provides spatially defined IPA and MA motifs that serve distinct surface and interfacial functions. Oxygen-containing IPA motifs tune Pt-surface reaction chemistry by promoting OH adsorption and transfer while weakening H-intermediate binding, whereas nitrogen-rich MA motifs reshape the interfacial electrostatic and water environment to enrich less constrained water species. As a result, the MA-IPA HOF simultaneously relieves the surface kinetic burden and improves the local interfacial reaction environment, thereby lowering the cathodic overpotential under low-alkalinity, ultralow-Pt-loading conditions. Implemented in a continuous-flow AEMWE with a Pt loading of only 0.03 mg cm-2, the HOF-engineered cathode delivers 8.0 A cm-2 at 2.0 V and 3.40 A cm-2 at 1.8 V in 1 wt % KOH. It further maintains continuous operation for 2000 h with a low degradation rate of 29.1 μV h-1, placing it among the most active and durable PGM-based AEMWE cathodes reported under dilute-alkaline and ultralow-noble-metal-loading conditions.