Corrosion Resistant Titanium Dioxide/Carbon Nanotube Composite Catalyst Supports

There is a need for novel materials to replace carbon black as platinum catalyst support in PEMFC that are more resistant to corrosion by electrochemical oxidation. The novel material investigated in this effort was Titania/multiwall carbon nanotube composite. TiO2-MWCNT was synthesized using a surfactant assisted wet chemical technique. The TiO2-MWCNT composite was obtained from chemical reaction between TiCl4 and hydroxyl functionalized MWCNT. D.C electrical conductivity vs. CNT content profiles showed adverse effects on conductivity beyond 17%. The addition of CNT conferred a maximum electrical conductivity of 0.87 S/cm, a value less than the target of 1 S/cm but sufficient for the intended function. XRD scans revealed the effective formation of anatase titania while the presence of CNT was indicated by the black color in the final TiO2 composite and SEM. Cyclic voltammetry scans at 8 hour-intervals, after oxidation at 1.2V vs. Ag/AgCl by chronoamperometry technique, demonstrated the superior resistance to corrosion of the synthesized TiO2-CNT as compared to commercial carbon black.

Cyclic voltammetry results from carbon black and the TiO2-CNT composite after 24 hours of chronoamperometry, showing the relative lack of oxidation peaks on the TiO2-CNT that indicates the composite's resistance to surface oxidation.