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-GO/WG (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 hours 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.

Keywords: nanoporous membrane, graphene, AEM, OH- conduction, O2/H2 isolation