Ultra-low loading of highly active Pt and PtSn catalysts on hierarchical tin as anodes in direct methanol fuel cells

Pt and PtSn catalysts were synthesized by a single-step electroless process on hierarchical three-dimensional electrodeposited branched metallic Sn structures (BMS). The controlled electrodeposition of Sn on a carbon-paper substrate resulted in a high surface area of BMS, on which the Pt and PtSn alloy catalysts were deposited as thin layers. The PtSn species were reduced on the Sn substrate from Pt-Sn complexes formed in the solution. Several synthetic aspects were studied, such as the acidity of the electroless solution and the electroless process time span. The prepared electrodes were applied as anodes in direct methanol fuel cells. Methanol oxidation on these electrodes exhibited a specific peak power density of 476 mW mg⁻¹ Pt at 0.45 V, 90 mA cm⁻² and 70°C, using only 75 μg cm⁻² of Pt, which is significantly higher than previously reported platinum-based catalysts.