Rostock 2019 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 24: Large and Reactive Systems

MO 24.4: Vortrag

Freitag, 15. März 2019, 11:15–11:30, S HS 002 Biologie

Transient absorption spectroscopy of nanodiamonds in water: direct observation of solvated electrons — •Christoph Merschjann¹, Franziska Buchner¹, Benjamin Kiendl², Amélie Venerosy³, Hugues Girard³, Jean-Charles Arnault³, Emina Hadzifejzovic⁴, John Foord⁴, Anke Krueger², and Tristan Petit¹ — ¹Helmholtz-Zentrum Berlin, Germany — ²Universität Würzburg, Germany — ³CEA-LIST, Saclay, France — ⁴University of Oxford, United Kingdom

Nanodiamonds (ND) are promising candidates for photocatalytic transformation of CO₂ to CO and organic reduction products like methanol or formic acid, as they release solvated electrons to the aqueous solution upon UV illumination. However, the nature of the electron emission process and its related dynamics are still unknown.

We investigate the ultrafast dynamics of this process using femtosecond transient absorption spectroscopy with DUV (225 nm) pump and VIS supercontinuum probe pulses. While the recombination of solvated electrons is governed by long-lived (> 2 ns) diffusion processes, NDs of different surface termination (-H, -OH, -COOH) show characteristic features in the sub-picosecond regime. We will discuss the impact of these surface terminations on the dynamics of solvated electrons, and thus on the photocatalytic performance in water. We expect that our results will support the design of efficient metal-free photocatalysts for CO₂ conversion.

Financial support by the European Union’s Horizon 2020 Program (Grant Agreement no. 665085, "DIACAT") is gratefully acknowledged.