Construction of dual-interface proton channels based on γ-polyglutamic acid@cellulose whisker/PVDF nanofibers for proton exchange membranes

In the present research, a novel composite proton exchange membrane with heterogeneous dual-interface proton transport channels are constructed by impregnating γ-polyglutamic acid functionalized cellulose whiskers/poly(vinylidene fluoride) nanofibers (PGA@CW/PVDF) into the sulfonated polysulfone matrix through a micro-impregnation method. The heterogeneous dual-interfaces generate enriched proton acceptors and donors facilitating the proton conduction, which is clarified by calculating the activation energy barriers of different proton transport pathway via density functional theory . The composite membrane with 15% content of PGA@CW/PVDF demonstrates a high proton conductivity of 0.582 S cm −1 (80 °C). Benefiting from the combined physicochemical and structural advantages of PGA@CW/PVDF and the matrix, the composite membrane achieves a low methanol permeability of 2.05 × 10 −7  cm 2  s −1 , an enhanced tensile strength of 44.61 MPa, and a competitive power density of 201.14 mW cm −2 . This study demonstrates a promising prospect in direct methanol fuel cell application .