Journal of Applied Electrochemistry, Vol.47, No.6, 735-745, 2017
Morphological transformation of electrodeposited Pt and its electrocatalytic activity towards direct formic acid fuel cells
Engineering the shape and size of platinum catalysts is crucial in determining fuel cell performance. In this study, Pt electrodeposited on carbon black-coated carbon paper at three different potentials (viz. 0.2, 0, and -0.2 vs. SHE) was evaluated for its performance in direct formic acid fuel cells (DFAFCs). The electrodeposited catalysts were analysed using SEM, XRD, and electrochemical techniques. The shape of the electrodeposited Pt transformed from globular (0.2 V) to dendritic (0 V) and to rosette-like (-0.2 V) structure by increasing the deposition potential in the cathodic direction. The change in shape could be due to the variation in the accompanying hydrogen evolution with the deposition potential in acidic electrolyte. The dendritic structure of Pt deposited at 0 V showed a higher electrochemical surface area and enhanced catalytic activity towards formic acid oxidation than the other two shapes. To study the performance of electrocatalysts in DFAFC, the anode catalyst was prepared in a new approach of layer-by-layer electrodeposition on carbon to maximize the triple phase boundary. The layered dendritic Pt generated a maximum power density of 42 mW cm(-2), comparable with the commercial Pt/C catalyst (46 mW cm(-2)) at 70 A degrees C for 3 M formic acid. [GRAPHICS] .
Keywords:Electrodeposition;Formic acid oxidation;Fuel cells;Layered catalyst preparation;Platinum;Shape control