SnO2-Nafion® nanocomposite polymer electrolytes for fuel cell applications

Fuel cells are capable to exploit the combustion of hydrogen to convert chemical energy into electricity. Polymer electrolyte fuel cells based on Nafion membranes are able to work in a relatively low temperature range (70–90ºC) but require operating relative humidity (RH) close to 100%. To develop proton-exchange membranes with adequate performances at low RH, an attractive strategy consists of the incorporation of inorganic fillers into the host Nafion polymer. Here, we report on the incorporation of SnO2 nanopowders with high acidic properties as fillers in Nafion-based polymer electrolytes. Nanometre-sized sulphated SnO2 particles have been synthesised and incorporated in Nafion polymer membranes. Morphological and vibrational properties of the oxides and membranes, as well as their electrochemical behaviour, have been investigated by atomic force microscopy (AFM), micro-Raman and infra-red (IR) spectroscopies and electrochemical impedance spectroscopy (EIS). The nanocomposite electrolytes have been used to form a membrane-electrodes assembly with commercial Pt-based catalysts and tested in hydrogen fuel cells.