Nature Communications (Aug 2024)

Accelerated proton dissociation in an excited state induces superacidic microenvironments around graphene quantum dots

  • Yongqiang Li,
  • Siwei Yang,
  • Wancheng Bao,
  • Quan Tao,
  • Xiuyun Jiang,
  • Jipeng Li,
  • Peng He,
  • Gang Wang,
  • Kai Qi,
  • Hui Dong,
  • Guqiao Ding,
  • Xiaoming Xie

DOI
https://doi.org/10.1038/s41467-024-50982-x
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 13

Abstract

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Abstract Investigating proton transport at the interface in an excited state facilitates the mechanistic investigation and utilization of nanomaterials. However, there is a lack of suitable tools for in-situ and interfacial analysis. Here we addresses this gap by in-situ observing the proton transport of graphene quantum dots (GQDs) in an excited state through reduction of magnetic resonance relaxation time. Experimental results, utilizing 0.1 mT ultra-low-field nuclear magnetic resonance relaxometry compatible with a light source, reveal the light-induced proton dissociation and acidity of GQDs’ microenvironment in the excited state (Hammett acidity function: –13.40). Theoretical calculations demonstrate significant acidity enhancement in –OH functionalized GQDs with light induction ( $${{\mathrm{p}}}{K}_{{\text{a}}}^{*}$$ p K a * = –4.62, stronger than that of H2SO4). Simulations highlight the contributions of edge and phenolic –OH groups to proton dissociation. The light-induced superacidic microenvironment of GQDs benefits functionalization and improves the catalytic performances of GQDs. Importantly, this work advances the understanding of interfacial properties of light-induced sp 2–sp 3 carbon nanostructure and provides a valuable tool for exploring catalyst interfaces in photocatalysis.