3 nm-sized porous graphene-based anion exchange membranes for efficient and stable water electrolysis

Abstract

Alkaline water electrolysis is one of the primary drivers of hydrogen energy development, and anion exchange membranes (AEMs) play a dual role in ensuring both conductivity and safety. However, traditional polymer AEMs have a wide pore size distribution and poor chemical stability, making it difficult to achieve a long-term balance between conductivity and safety of the water electrolysis system. Here, we select inorganic two-dimensional multilayer graphene oxide (GO) membranes as AEMs, using carboxylated wrinkled graphene (WG) and ethylenediamine (EDA) to create a cation-modified porous EDA-WG/GO (E-W/G) composite membrane with a 3 nm pore size. The enlarged channel size and enhanced hydrophilicity improve OH⁻ permeability compared to the pristine GO membrane, while the strengthened hydration layer acts as a barrier to hydrophobic gases for O₂/H₂ separation. The results show that the prepared E-W/G membrane exhibits superior current density (600 mA cm⁻²) and gas impermeability (gas purity 99.99%) compared to the commercial Fumasep FAA-3-50 membrane (590 mA cm⁻² and 99.81%, respectively). Furthermore, after continuous testing for 168 h in high-temperature and alkaline environments, the E-W/G membrane maintained conductivity comparable to its initial state and showed enhanced gas impermeability. Our strategy provides new insights into the design of high-performance AEMs and is expected to contribute to the advancement of the hydrogen energy industry.