Pulsed Electrodeposition of Metastable Pd₃₁Bi₁₂ Nanoparticles for Oxygen Reduction Electrocatalysis

Metastable alloys have recently emerged as high-performance catalysts, extending the toolbox of binary alloy materials that can be utilized to mediate electrocatalytic reactions. In particular, nanostructured metastable ordered intermetallic compounds are challenging to synthesize. Here we report a method for synthesizing sub-15 nm metastable ordered intermetallic Pd31Bi12 nanoparticles at room temperature, in a single step, by pulsed electrochemical deposition onto high surface area carbon supports. The resulting Pd31Bi12 nanoparticles displays a 7× enhancement of the mass activity relative to Pt/C and a 4× enhancement relative to Pd/C for the oxygen reduction reaction (ORR). The high performance of Pd31Bi12 nanoparticles is demonstrated to arise from reduced oxygen binding caused by alloying of Pd with Bi. We also demonstrate that the isolation of Pd sites from each other facilitates methanol-tolerant ORR behavior.