Enhanced Mass Activity and Stability of Bimetallic Pd-Ni Nanoparticles on Boron-Doped Diamond for Direct Ethanol Fuel Cell Applications

In this work, electrochemical deposition of Pd and bimetallic Pd−Ni nanoparticles on an oxygen-terminated boron-doped diamond (BDD) substrate is described for use as an electrocatalyst in a direct ethanol fuel cell. A potentiostatic two-step electrochemical method involving the electrodeposition of Ni nanoparticles on BDD followed by mono-dispersed Pd nanoparticles was used for the fabrication of a Pd−Ni/BDD electrode. The electrocatalytic activity of the bimetallic Pd−Ni nanoparticles was evaluated in an alkaline solution containing ethanol and compared to that of the Pd nanoparticles alone. The bimetallic Pd−Ni nanoparticles showed 2.4 times higher mass activity than similar systems in the literature as well as stability when operated in alkaline media. The higher electrochemical response towards the electrooxidation of ethanol observed for the bimetallic electrocatalysts was attributed to the synergistic effects of the electron interaction at the interface of the two metals. Chronopotentiometric measurements revealed that Pd is more stable when anchored to the Ni nanoparticles. The optimised loading of mono-dispersed Pd on a foreign Ni metal as nanoparticles plays a crucial role in achieving a high mass (3.63×10⁶ mA/g) and specific (10.53 mA/cm²) electrocatalytic activity of Pd towards ethanol electrooxidation in alkaline media.