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Hybrid composite membranes possess the desired properties than that of the pristine polymeric membranes for fuel cell applications. Phase inversion method was used to entrap silicotungstic acid (STA) particles in Sulfonated Poly Ether Ether Ketone (SPEEK) membranes as a source of protons having a high protonic conductivity at room temperature (0.02–0.1 S/cm). The physico-chemical properties of the hybrid membranes were characterized by SEM-EDX, line scanning, 3D non-contact profilometer, FTIR and XRD techniques. These membranes showed better ion exchange, proton conductivity values and were tested in single chamber microbial fuel cell (SCMFC). In addition, these membranes show decreased oxygen crossover and transport of cations other than protons. Among the various weight percentage (2.5%, 5%, 7.5% and 10%) of STA prepared composite membranes, 7.5% STA + SPEEK showed the highest power density of 207 mWm−2 compared to that of commercial Nafion 117 (47 mWm−2) in the same setup of SCMFC. Overall, the composite membranes proved to be excellent candidates as electrolytes for Microbial Fuel Cell (MFC) applications.

Rutile TiO 2 was synthesized using the sol gel method and used for the preparation of polymer composite electrolyte membrane of TiO 2 +SPEEK. The composite membranes prepared by solvent casting method showed improved oxygen mass transfer coefficient values and the transport of cations other than protons. The antifouling property of the composite membranes was observed in SEM images which were additionally supported by hemocytometer results. The improved ion exchange and water absorption capacity of composite membranes showed enhanced proton conductivity and electrochemical properties for the composite membranes. The prepared composite membranes were evaluated in single chamber microbial fuel cell and the results were compared with that of the Nafion 117 ® under similar conditions. The results revealed that all the prepared composite membranes showed higher maximum power density and current density than that of the commercially available Nafion117 ® . Among the prepared membranes, SPEEK+7.5% TiO 2 composite membrane showed the highest power density (98.1 mW/m 2 ) and current density (300 mA/m 2 ) along with high proton conductivity, antifouling property.

The influence of Fe3O4 in proton conductivity, oxygen crossover, water absorption and performance of Sulfonated Poly Ether Ether Ketone (SPEEK) matrix was studied in single chamber microbial fuel cell at various weight percentages (2.5%, 5%, 7.5%, 10%) of SPEEK/Fe3O4. The fabricated composite membranes were characterized by FT-IR, SEM, and XRD which were also tested for their surface roughness, water absorption, proton conductivity and transportation of cations were also studied for its suitability in microbial fuel cell operation. Escherichia coli (E. coli), an electrogenic bacteria, was used as the biocatalyst in anodic chamber and platinized carbon (Pt/C) was used as the catalyst in the air cathode. The low oxygen crossover, selective transfer of protons and water mediated proton hopping mechanism in Fe3O4 composite membrane (7.5% Fe3O4) resulted in a maximum power density of 104 mW m−2 which was higher than that of the power density of Nafion® 117 (47 mW m−2) under the same operating conditions. The results of the study suggested that SPEEK/Fe3O4 (7.5 wt%) composite membrane would be more commercially viable and efficient than the existing Nafion membranes for use in microbial fuel cells.

The influence of Multi Walled Carbon Nano Tube (MWCNT) in oxygen cross over, water absorption and performance of chitosan (CHIT) in Single Chamber Microbial Fuel Cell (SCMFC) was studied. CHIT and non covalently functionalized MWCNT with CHIT (CHIT–MWCNT) were prepared in the form of membranes and characterized using FTIR, XRD, DRS UV, CD, Raman, SEM and TEM to study the interaction of MWCNT with chitosan. CHIT–MWCNT showed lesser water absorption compared to that of CHIT. CHIT–MWCNT membrane showed oxygen mass transfer coefficient (2.66×10 −4 cm/s) one order less than that of CHIT (2.28×10 −3 cm/s). The prepared membranes were continuously tested in an in-house built Single Chamber Microbial Fuel Cell (SCMFC). The maximum power density obtained by CHIT–MWCNT composite membrane was higher compared to that of CHIT membrane obtained was 38.16 mW/m 2 and 46.94 mW/m 2 for CHIT and CHIT–MWCNT, respectively. The results of the study showed that the MWCNT incorporated chitosan composite membrane had strong influence on the properties and performance of CHIT in microbial fuel cell. Hence, CHIT–MWCNT is a promising candidate for application in microbial fuel cell.