A major challenge in treating acidic wastewater containing heavy metal ions lies in the scarcity of membranes that simultaneously exhibit high proton permeability, selectivity, and chemical stability. Here, we report a hydroxyl-functionalized porous organic framework (POF) membrane with an engineered hydrogen bonding network that addresses these limitations. The introduction of hydroxyl groups not only enables the formation of hydrogen bonds, which can shield imine bonds from hydrolysis under acid attack, but also provides an efficient pathway for Grotthuss proton hopping, facilitating rapid proton transport. Concurrently, the functional groups enable strong coordination with heavy metal ions, which reduces the effective pore size and significantly suppresses their diffusion, while leaving proton mobility largely unaffected. As a result, the membrane achieves a high proton permeability of 2.96 mol m⁻² h⁻¹ and a proton/Fe³⁺ selectivity of 3780. Furthermore, during acid recovery, the membrane generates remarkable osmotic power with a power density up to 37.6 W m⁻². This work provides a scalable strategy for designing stable, high-performance proton-conductive membranes and demonstrates their dual functionality in acidic wastewater treatment and renewable energy harvesting.

Biological proton pumps ferry protons in an active manner and have a high flux (a few to 10 protons/(s·nm²)). Integrating these features in an artificial membrane may open the way for a wide range of applications but it remains challenging. In this work, we employed a structural engineering strategy to construct an asymmetric photonic polymeric carbon nitride (C₃N₄) membrane that exhibited photo-driven high flux proton pumping performance. The ion transport path through the membrane is reminiscent of that in the high-flux asymmetric biological ion channel. In addition, it has a photonic structure that mimics the mosquito compound eyes with improved light adsorption. Finally, the asymmetric structure constitutes an isotype (n–n) heterojunction that enhances the separation of the light-induced electron–hole pairs. As a result, the membrane shows a flux of 89 μA/cm² under 100 mW/cm² white light illumination (approximately one sun), the highest ever reported. This translates to a pumping rate of ~ 6 proton/(s·nm²), comparable to the biological counterpart. This work highlights the potential of multi-level structural engineering to construct high-performance bionic devices, and may find applications in solar energy harvesting and solar powered membrane process.