Size-dependent activity of carbon dots for photocatalytic H2 generation in combination with a molecular Ni cocatalyst

Carla Casadevall, Ava Lage, Manting Mu, Heather F. Greer, Daniel Antón-García, Julea N. Butt, Lars J. C. Jeuken, Graeme W. Watson, Max Garcia-Melchor, Erwin Reisner (Lead Author)

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Abstract

Carbon dots (CDs) are low-cost light-absorbers in photocatalytic multicomponent systems, but their wide size distribution has hampered rational design and the identification of the factors that lead to their best performance. To address this challenge, we report herein the use of gel filtration size exclusion chromatography to separate amorphous, graphitic, and graphitic N-doped CDs depending on their lateral size to study the effect of their size on photocatalytic H 2 evolution with a DuBois-type Ni cocatalyst. Transmission electron microscopy and dynamic light scattering confirm the size-dependent separation of the CDs, whereas UV-vis and fluorescence spectroscopy of the more monodisperse fractions show a distinct response which computational modelling attributes to a complex interplay between CD size and optical properties. A size-dependent effect on the photocatalytic H 2 evolution performance of the CDs in combination with a molecular Ni cocatalyst is demonstrated with a maximum activity at approximately 2-3 nm CD diameter. Overall, size separation leads to a two-fold increase in the specific photocatalytic activity for H 2 evolution using the monodisperse CDs compared to the as synthesized polydisperse samples, highlighting the size-dependent effect on photocatalytic performance.

Original languageEnglish
Pages (from-to)15775-15784
Number of pages10
JournalNanoscale
Volume15
Issue number38
Early online date28 Aug 2023
DOIs
Publication statusPublished - 14 Oct 2023

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