Bifunctional Pt-Ni Electrocatalyst Synthesis with Ultralow Platinum Seeds for Oxygen Evolution and Reduction in Alkaline Medium

Pt-Ni polyhedral nanoparticles (NPs) are extensively studied as electrocatalysts, mainly for oxygen reduction reaction (ORR), but they display a poor activity for the oxygen evolution reaction (OER). Here, ultralow platinum Pt@Ni@Pt core-bishell nanorods were designed (less than 1 wt % of Pt), synthesized, and characterized to yield bifunctional electrocatalysts with high efficiency toward ORR and OER in alkaline media. Ultralow platinum Pt@Ni@Pt core-bishell nanorods achieve an unprecedented (for a Pt-based catalyst) overpotential of 0.29 V at 10 mA cm^-2and current density of 162 mA μg^-1_Ptat 1.6 V (vs RHE) for the OER, while still maintaining a very decent value of 0.32 A mg^-1_Ptat 0.85 V for the ORR. These values outperform the standard Pt catalyst for the ORR and the Ni catalyst for the OER, using less than 1 wt % Pt. We describe the two-step synthesis of the Pt@Ni@Pt nanorods, demonstrating the adjustment of their structural properties by a combination of dimethylformamide (DMF) and benzyl alcohol in a solvothermal reaction. We found that the solvent ratio controls the Pt-core size, Ni-shell thickness, and morphology. The combination of high performance and structure control via synthesis makes Pt@Ni@Pt nanorods promising candidates for further applications and opens a door for their further investigation.