Platinum-based transition metal alloy materials have been considered promising candidates as industrial catalysts for decades. Shape-controlled Ni-alloyed Pt nanocatalysts show enhanced catalytic conversion at the liquid/solid interface. Specifically, the elaborate novel structure of Pt-skin/Pt3Ni would provide a chemical reaction pathway with highly efficient charge transfer on the surface. Dissociated oxygen could also pull sub-surface Ni onto the topmost layer of the Pt-Ni catalyst, which occurs spontaneously when there is a theoretical low-energy barrier. Thus, the segregated Ni oxide complex makes a Pt-NiO1-x interfacial structure. This adsorbate-driven nanostructure formation correlates strongly with an improved conversion rate of carbon monoxide molecules via the strong metal–support interaction effect along the perimeter. In this study, we show the interfacial structure of Pt-NiO1-x/Pt3Ni at the gas/solid interface during the CO oxidation reaction using combined real-time imaging (environmental transmission electron microscopy, E-TEM) and in situ spectroscopic techniques (X-ray photoelectron spectroscopy, XPS; and diffuse reflectance infrared Fourier-transform spectroscopy, DRIFT) to investigate the surface catalytic reactions. The operando observations show oxygen-driven Ni oxide cluster segregation at the interface and provide direct evidence of Pt-NiO1-x interfacial structure formation. The spectroscopic analysis suggests that CO molecules are selectively adsorbed on the Pt atoms, and that effective molecular conversion takes place immediately at the interface. These straightforward investigations explain the role of interfacial structures as an active site on the surface. These fundamental results also propose the tremendous potential for the utilization of catalytronics in future technology.

Unraveling catalytically active Pt-NiO1-x interfacial structure formations on the bimetallic PtNi nanocrystal surface

2019 Fall National Meeting

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