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

Abstract

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 −2 and current density of 162 mA μg −1 Pt at 1.6 V (vs RHE) for the OER, while still maintaining a very decent value of 0.32 A mg −1 Pt at 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 twostep 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.

Activity Restoration of Pt–Ni Octahedron via Phase Recovery for Anion Exchange Membrane‐Unitized Regenerative Fuel Cells

“…[ 9a,15 ] A catalyst passivated by oxidation cannot maintain its bifunctional ability, especially for the ORR, because the diffusion of oxygen toward the catalyst is hindered. Because Ni oxides have superior OER activity to Pt, [ 14a,16 ] the OER primarily occurs on Ni during the URFC process. Thus, even if the activity of Pt is reduced by passivation, the overall OER activity is maintained.…”

Nanostructured Pt-based catalysts for oxygen reduction reaction in alkaline media

“…The structure is presented in Figure 3. As a result, Pt@Ni@Pt maintained a very high MA value of 0.32 A•mgPt -1 at 0.85 V for the ORR [44]. Soto-Pérez et al also constructed PtNi-Nanowire by a solvothermal reaction and loaded it on Vulcan (PtNi-NWs/V), and PtNi-NWs/V provided the highest specific activity with logarithmic values of 0.707 and 1.01 (mA•cmPt -2 ) at 0.90 and 0.85 V vs RHE, respectively.…”

“…[49], Pt37Cu56 Au7 porous film [50], PtML/Pd9Au1/C [51], PtPdIr [52], which can modulate the oxygen binding energy, weakening it in comparison with to the Pt (111) surface, of the Pt-based catalysts [53]. Pt/C reference Nanoparticles 0.054 0.555 [44] PtS@NiS Core shell nanoparticles 0.002 0.012 [44] PtM@NiM Core shell nanoparticles 0.019 0.172 [44] PtL@NiL Core shell nanoparticles 0.001 0.003 [44] Pt@NiXL Core shell nanoparticles 0.029 0.023 [44] PtNi-NWs Nanowires 0.133 0.023 [45] PtNi-NWs/V (V= Vulcan) Nanowires 0.446 0.071 [45] PtNi-NWs/V-NH3 (V= Vulcan) Nanowires 0.337 0.001 [45] Commercial Pt/V (V= Vulcan) Nanoparticles 0.696 0.090 [45]…”

Gram-Scale Synthesis of Carbon-Supported Sub-5 nm PtNi Nanocrystals for Efficient Oxygen Reduction

“…The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/met12071078/s1, Figure S1 S1: ICP-OES results for various PtNi/C samples; Table S2: Fitting data of EIS results of commercial Pt/C-20% and PtNi/C-200 in 0.1 M KOH; Table S3: Comparison of the alkaline ORR activity of different Pt-based catalysts. References [39][40][41][42][43][44][45][46] are cited in Supplementary Materials. Institutional Review Board Statement: Not applicable.…”