Study of poly(vinyl alcohol)/titanium oxide composite polymer membranes and their application on alkaline direct alcohol fuel cell

The novel poly(vinyl alcohol)/titanium oxide (PVA/TiO₂) composite polymer membrane was prepared using a solution casting method. The characteristic properties of the PVA/TiO₂ composite polymer membrane were investigated by thermal gravimetric analysis (TGA), a scanning electron microscopy (SEM), a micro-Raman spectroscopy, a methanol permeability measurement and the AC impedance method. An alkaline direct alcohol (methanol, ethanol and isopropanol) fuel cell (DAFC), consisting of an air cathode based on MnO₂/C inks, an anode based on PtRu (1:1) black and a PVA/TiO₂ composite polymer membrane, was assembled and examined for the first time. The results indicate that the alkaline DAFC comprised of a cheap, non-perfluorinated PVA/TiO₂ composite polymer membrane shows an improved electrochemical performances. The maximum power densities of alkaline DAFCs with 4 M KOH + 2 M CH₃OH, 2 M C₂H₅OH and 2 M isopropanol (IPA) solutions at room temperature and ambient air are 9.25, 8.00, and 5.45 mW cm^-2, respectively. As a result, methanol shows the highest maximum power density among three alcohols. The PVA/TiO₂ composite polymer membrane with the permeability values in the order of 10^-7 to 10^-8 cm² s^-1 is a potential candidate for use on alkaline DAFCs.