Organically functionalized titanium oxide/Nafion composite proton exchange membranes for fuel cells applications

Higher ion exchange capacity (IEC) and proton conductivity of the hybrid material (one order of magnitude higher for the functionalized filler) reflected in superior performance of Nafion/TiO2-RSO3H composite membranes compared to Nafion. The highest conductivity value was obtained for the composite membrane containing 10 wt. % TiO2-RSO3H (σ = 0.08 S cm−1 at 140 °C). The membranes were tested in a DMFC single cell. The presence of the filler resulted in a general enhancement in the cell response, in terms of both higher power density (PD) delivered and lower methanol crossover with respect to unfilled Nafion membrane. The DMFC containing N_10TiO2-RSO3H membrane showed the best performance at 110 °C with a PD of 64 mW cm−2, corresponding to a PD improvement of about 40% with respect to that of Nafion membrane.