THE STUDY OF HIERARCHAL SHAPE Tin USED AS CATALYSTS SUPPORT TOWARDS A BINDER FREE FUEL CELL ANODES

A novel catalyst support utilizing electrodeposited tin was investigated for direct liquid fuel cells. These materials were prepared by electrodeposition of tetragonal metallic Sn on Toray® carbon paper or gold electrodes under non-equilibrium conditions. Hierarchical shape branched dendrites of Sn were formed under selected experimental conditions. The growth processes on these electrodes were rigorously investigated using potentiostatic or galvanostatic steps, in aqueous solutions containing sodium citrate, SDS, HTAB.

Various morphologies of metallic Sn can be prepared by controlling the applied potential, duty cycle and the acid additives. Hierarchal morphologies of Sn start to appear at an over potentials of more than 0.9V and is strongly influenced by hydrogen evolution competing reaction. Characterization of the deposition the deposition and etching, passivation and activation processes were performed by EQCM.

Pt, PtSn and Ni catalysts were coated as thin layer on electrodeposited Sn supported on Toray® carbon paper by electroless or by electroplating processes. These binder free anodes were measured in methanol, methyl-formate in acid solutions, and nickel-plated was applied in urea oxidation in alkaline solutions. Superior oxidation specific activity was observed on all Sn supported anodes with respect to Pt or Ni catalysts loaded on carbon XC72.

The role of a thin layers of Pt formed on metallic tin was investigated by calculations using DFT based VASP approach. A very distinctive CO adoption behavior was revealed in support of our observed catalysts activity.