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Operando Evolution of the Structure and Oxidation State of Size-Controlled Zn Nanoparticles during CO₂ Electroreduction

Jeon, Hyo Sang, Sinev, Ilya, Scholten, Fabian, Divins, Nuria J., Zegkinoglou, Ioannis, Pielsticker, Lukas, Cuenya, Beatriz Roldan
Journal of the American Chemical Society 2018 v.140 no.30 pp. 9383-9386
carbon dioxide, catalysts, electrochemistry, hydrogen production, nanoparticles, oxidation, spectroscopy, zinc
We explored the size-dependent activity and selectivity of Zn nanoparticles (NPs) for the electrochemical CO₂ reduction reaction (CO₂RR). Zn NPs ranging from 3 to 5 nm showed high activity and selectivity (∼70%) for CO production, whereas those above 5 nm exhibited bulk-like catalytic properties. In addition, a drastic increase in hydrogen production was observed for the Zn NPs below 3 nm, which is associated with the enhanced content of low-coordinated sites on small NPs. The presence of residual cationic Zn species in the catalysts was also revealed during CO₂RR via operando X-ray absorption fine-structure spectroscopy measurements. Such species are expected to play a role in the selectivity trends obtained. Our findings can serve as guidance for the development of highly active and CO-selective Zn-based catalysts for CO₂RR.