*Article* **A Highly Selective Novel Green Cation Exchange Membrane Doped with Ceramic Nanotubes Material for Direct Methanol Fuel Cells**

**Marwa H. Gouda , Tamer M. Tamer \* and Mohamed S. Mohy Eldin \***

Polymer Materials Research Department, Advanced Technology and New Materials Research Institute (ATNMRI), City of Scientific Research and Technological Applications (SRTA-City), Alexandria 21934, Egypt; mgouda@srtacity.sci.eg

**\*** Correspondence: tmahmoud@srtacity.sci.eg (T.M.T.); mmohyeldin@srtacity.sci.eg (M.S.M.E.)

**Abstract:** Herein, a pair of inexpensive and eco-friendly polymers were blended and formulated based on poly (ethylene oxide) (PEO) and poly (vinyl alcohol) (PVA). FTIR, XRD, EDX and TEM techniques were used to describe a Phosphated titanium oxide (PO4TiO2) nanotube synthesised using a straightforward impregnation-calcination procedure. For the first time, the produced nanoparticles were inserted as a doping agent into this polymeric matrix at a concentration of (1–3) wt.%. FTIR, TGA, DSC and XRD were used to identify the formed composite membranes. Furthermore, because there are more hydrogen bonds generated between the polymer's functional groups and oxygen functional groups PO4TiO2, oxidative stability and tensile strength are improved with increasing doping addition and obtain better results than Nafion117. The permeability of methanol reduced as the weight % of PO4TiO2 increased. In addition, the ionic conductivity of the membrane with 3 wt.% PO4-TiO2 is raised to (28 mS cm<sup>−</sup>1). The optimised membrane (PVA/PEO/PO4TiO2-3) had a higher selectivity (6.66 × 105 S cm−<sup>3</sup> s) than Nafion117 (0.24 × 10<sup>5</sup> S cm−<sup>3</sup> s) and can be used as a proton exchange membrane in the development of green and low-cost DMFCs.

**Keywords:** proton exchange membrane; poly (vinyl alcohol); poly (ethylene oxide); titanium oxide; direct methanol fuel cell; fuel cell
