Graphene oxide/SPEEK nanocomposite proton exchange membranes for enhanced bioelectricity generation and biofouling resistance in microbial fuel cells

Microbial Fuel Cells (MFCs) have emerged as a promising technology for simultaneously treating wastewater and generating renewable energy. However, their large-scale application is still limited by the drawbacks of conventional proton exchange membranes, such as Nafion, primarily due to their high cost. Sulfonated poly(ether ether ketone) (SPEEK) has therefore attracted considerable attention as a lower-cost alternative membrane with good proton conductivity. Nevertheless, pristine SPEEK membranes often suffer from excessive swelling and limited mechanical stability. To overcome these limitations, nanocomposite membranes incorporating graphene oxide (GO) have been developed to improve structural stability and electrochemical performance. In this study, SPEEK membranes incorporating GO nanosheets were developed as a cost-effective, high-performance alternative. GO was introduced into the SPEEK matrix at loadings ranging from 0.5 to 3.0 wt%, and the resulting nanocomposite membranes were systematically characterized by various spectroscopy and microscopy techniques. Among the prepared samples, the membrane containing 2.0 wt% GO exhibited the most balanced physicochemical properties, including a proton conductivity of 0.089 S cm −1 at 30 °C, a water uptake of 34.2%, and an ion exchange capacity of 1.62 meq g −1 . When evaluated in a dual-chamber MFC system, this optimized membrane achieved a maximum power density of 480 mW m −2 , a Coulombic efficiency of 47.3%, and a COD removal efficiency of 94.6% within 72 hours of operation. Furthermore, long-term stability testing over 60 days demonstrated only a 7.2% reduction in performance, indicating significantly improved stability compared with Nafion 117 under identical operating conditions. Surface analysis revealed reduced biofouling on the SPEEK/GO membrane, indicating improved resistance to microbial adhesion. These findings demonstrate that incorporating GO into SPEEK is an effective strategy for enhancing membrane performance and durability in MFC applications.