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Tailoring the active site for the oxygen evolution reaction on a Pt electrode

ABSTRACT: Highly active electrocatalysts for the oxygen evolution reaction (OER) are essential to improve the efficiency of water electrolysis. The properties of OER active sites on single-crystal Pt electrodes were examined herein. The OER is markedly enhanced by repeated oxidative and reductive potential cycles on the Pt(111) surface. The OER activity on Pt(111) is nine times higher in the third cycle than that before the potential cycles. OER activation by potential cycling depends on the (111) terrace width, with wider (111) terraces significantly enhancing the OER. The oxidation/reduction of the Pt(111) surface produces atomic-sized vacancies on the terraces that activate the OER. Structural analysis using X-ray diffraction reveals that the active sites formed by potential cycling are defects in the second subsurface Pt layer. Potential cycling induces the bowl-shaped roughening of the electrode surface, wherein high-coordination number Pt atoms at the bottom of the cavities activate the OER. Electrocatalytic oxygen evolution is a key reaction for water splitting, but the detailed atomic structures of single-crystal electrodes under cycling conditions are still not fully understood. Here, the authors study the oxygen evolution activity on Pt(111) during potential cycling and find that the current density reaches a maximum in the third cycle and is nine times higher than that in the initial cycle, owing to a roughened Pt(111) surface and formation of islands and atomic vacancies in the second subsurface Pt layer.

SUBMITTER: Iizuka K

PROVIDER: S-EPMC9814662 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature

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