Synthesis and characterization of conductive polymer coated graphitic carbon nitride embedded sulfonated poly (ether ether ketone) membranes for direct methanol fuel cell applications

Abstract

Direct methanol fuel cell (DMFC) is a sustainable energy conversion device that is known for its advantages in terms of portability as well as can be stored and transported safely. Functionalized nanostructured materials have been used in proton exchange membrane (PEM) for DMFC applications to enhance the proton conductivity and suppress the methanol permeability. In this study, conductive polyaniline deposited oxidized graphitic carbon nitride (PANI-O-g-C3N4) was incorporated in sulfonated poly (ether ether ketone) (SPEEK) membrane for DMFC applications. The performances of graphitic carbon nitride (g-C3N4) and oxidized graphitic carbon nitride (O-g-C3N4) on SPEEK PEM were also assessed and compared. The morphological and X-ray diffraction analysis indicated that the structure and crystallinity were altered with the deposition of PANI on g-C3N4. The scanning electron microscopy and topography analysis revealed that the existence of g-C3N4 and functionalized g-C3N4 were clearly seen on the surface of the SPEEK membrane. Water uptake capacity and ion exchange capacity were significantly improved in the functionalized g-C3N4-modified SPEEK membrane (O-g-C3N4/SPEEK and PANI-O-g-C3N4/SPEEK). The lower methanol permeability and higher proton conductivity of 3.71 × 10-7 cm-2 S-1 and 5.34 × 10-3 S cm-1 were recorded by 0.1 wt% PANI-O-g-C3N4 incorporated SPEEK membrane. Functionalized g-C3N4-modified SPEEK membrane also exhibited higher oxidative stability. The performance of the PANI-O-g-C3N4 incorporated SPEEK membrane in DMFC application highlights its potential as a superior nanofiller for the modification of PEM.