Size-controllable synthesis of dendritic Pd nanocrystals as improved electrocatalysts for formic acid fuel cells’ application

Abstract

Control over size and shape of Pd nanocrystals is critical for highly active and stable catalysts in direct formic acid fuel cells’ application. In this work, dendritic Pd nanocrystals have been successfully synthesized using a facile, environmentally friendly approach in an aqueous solution below 100 °C. The size of as-synthesized dendritic Pd nanocrystals has a narrow distribution, about 57.5 ± 7.5 nm. The dendritic Pd nanocrystals exhibit much superior electrocatalytic properties for formic acid oxidation compared with commercial Pd black in acidic medium. The specific activity and mass activity toward formic acid oxidation on dendritic Pd nanocrystals are 5.14 mA/cm2 and 3.3 A/mg in perchloric acid solution, 2.0 mA/cm2 and 1.08 A/mg in sulfuric acid solution, respectively. And for commercial Pd black, the specific activity and mass activity are 2.08 mA/cm2 and 0.36 A/mg in perchloric acid solution, 0.68 mA/cm2 and 0.12 A/mg in sulfuric acid solution. Furthermore, chronoamperometric measurements show that the dendritic Pd nanocrystals have excellent stability over commercial Pd black. Keywords: Dendritic Pd nanocrystals, Eletrocatalysis, Formic acid oxidation, Fuel cells