Platinum (Pt) based electrocatalysts is central for many electrochemical reactions, such as the hydrogen evolution reaction, alcohol oxidation reaction, and oxygen reduction reaction. The activity of Pt based catalysts largely depends on their geometric shape, surface composition, and electrochemical active surface area. PtM (M=Fe, Co, Ni) based tetrahedron has rarely been synthesized and studied due to it higher suface volume ratio and lower symmetry compared with PtM octahedron. Herein, we report a controlled-synthesis of PtNi tetrahedrons with exceptional electrochemical activity towards HER. The regulated growth of high quality PtNi tetrahedrons were ascribed to the rapid nucleation and facet confinement induced by introducing W(CO)6 as both the nucleation agent and capping agent. Study of growing mechanism shows that the W-controlled nucleation step in tandem with the preferential adsorption of CO on PtNi {111} are the central factor that regulate the shape formation. Meanwhile, PtNitet features a Pt rich tetrapod-skeleton and Ni(OH)2 rich PtNi {111} surface due to the different decomposition rate of precursors and deposition preference of the Pt and Ni atoms on the nucleates. It is found that Pt prefer to deposit on the along the &lt;111&gt; direction to form Pt tetrapod while Ni prefer to deposit on the concave structure in-between these Pt pods. Benefited from the unique (111) enclosed tetrahedron structure and the Pt/Ni(OH)2 interface, the PtNi tetrahedrons show an boosted HER activity in 1 M KOH with mass activity of 13.4 ± 0.2 A/mgPt at -70 mV vs. RHE, which is over 17.8 times higher than the activity of commercial Pt/C . This novel shape and surface control will fulfill the blank of the Pt alloy tetrahedron synthesis that is unachieved for decades. Its high HER activity and stability resulted from the Pt/Ni(OH)2 interface engineering is also an important step towards tailorable catalysts for a variety of reactions, vital for future energy demand.

Synthesis of PtNi tetrahedrons with exceptional activity for hydrogen evolution reaction

2019 Fall National Meeting

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