Enhanced Performance of Sulfonated GO in SPEEK Proton-Exchange Membrane for Microbial Fuel-Cell Application

Sulfonated graphene oxide (SGO) was prepared using sulfuric acid and used as a nanofiller at various concentrations in self-fabricated sulfonated polyetheretherketone (SPEEK) to produce nanocomposite proton-exchange membranes for microbial fuel-cell (MFC) applications. The proton conductivity, water uptake, ion-exchange capacity (IEC), and MFC performance of the nanocomposite membranes (SPEEK-SGO) were compared with those of pristine SPEEK and SPEEK-graphene oxide (GO). The addition of sulfonated GO (2% by weight) in a SPEEK membrane enhanced the proton conductivity and showed the maximum power density of 1,028±7 mW·m−2 compared with SPEEK (570±4 mW·m−2) and SPEEK-GO (704±6 mW·m−2) membranes in a single-chamber MFC. The SPEEK-SGO 2% membrane exhibited a onefold greater performance than the Nafion 115 (sulfonated tetrafluoroethylene) membranes (512±6 mW·m−2) in the same MFC arrangement. The enhanced result of the SGO membranes was attributed to the presence of a high-density of sulfonic acid ─ SO3H, ─ OH, and ─ COOH on SGO, which facilitates higher water uptake, proton conductivity, and IEC of the membrane.