Hydrophilicity/porous structure-tuned, SiO2/polyetherimide-coated polyimide nonwoven porous substrates for reinforced composite proton exchange membranes

► Porous substrate-reinforced Nafion composite membrane. ► Silica (SiO2)/polyetherimide (PEI)-coated PI nonwoven porous substrates. ► Importance of SiO2 size in tuning porous structure and properties of the substrates. ► Porous substrate crucially affects performance of reinforced composite membranes.