Electrodeposited Pt–Pd dendrite on carbon support as anode for direct formic acid fuel cells

The activity of bimetallic catalyst is predominantly determined by its composition and its shape. In this work, Pt–Pd bimetallic catalysts were codeposited using cyclic voltammetry on a carbon black-coated carbon paper at two different potential ranges (0 to 1.3 V and − 0.2 to 1.3 V vs. SHE) and with two different Pt precursors (H2PtCl6 and K2PtCl4). SEM analysis revealed that the deposit obtained from both K2PtCl4 and H2PtCl6 precursor resembled the shape of a flower-like dendrite when the deposition potential window was in the range of 0 to 1.3 V. However, shifting the lower potential limit from 0 to − 0.2 V resulted in a leaf-like dendritic structure, irrespective of the Pt precursor used. Leaf-like dendritic structures showed enhanced formic acid oxidation activity with high mass activity and superior stability compared to flower-like structures. The superior performance of the leaf-like structure was clearly evident from fuel cell polarization studies carried out at 70 °C, which showed a maximum power density of 49 mW cm−2, whereas flower-like structures showed a power density of 20 mW cm−2.