Rapid and effective self-healing of graphene oxide membranes enabled by alginate functionalization

Cross-linking graphene oxide (GO) membranes enhances separation performance by meticulously regulating nanochannels and interactions between GO flakes. However, achieving self-healing for localized damage, such as mechanical scratches, still remains a crucial challenge in prolonging membrane lifespan and minimizing costs. Here, we have innovatively designed a reduced GO membrane functionalized with sodium alginate (SA@rGO), which demonstrates rapid and effective self-healing performance. For blade damages with a width of ∼10 μm, rapid repair can be achieved within 10 min by the addition of a minute quantity of CaCl₂ solution. Through various dye rejection experiments, it was observed that both the rejection rate and permeance of the damaged membrane were rapidly restored to their original levels. During the long-term separation experiments over 100 h, our membrane exhibited exceptional rejection stability, further underscoring its excellent healing capabilities. Element mapping via scanning electron microscopy (SEM) and synchrotron radiation-based Fourier-transform infrared (SR-FTIR) spectroscopy indicated that calcium ions interact with SA molecules to form a hydrogel network, effectively 'stitching' the damaged areas together and enabling self-repair. Consequently, our self-healing functionality significantly elevates the potential of GO membranes for nanofiltration applications.