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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Inorganic ligands-mediated hole attraction and surface structuralreorganization in InP/ZnS QD photocatalysts studied via ultrafast visibleand midinfrared spectroscopies

Author

  • Yang Liu
  • Ying Zhou
  • Mohamed Abdellah
  • Weihua Lin
  • Jie Meng
  • Qian Zhao
  • Shan Yu
  • Zhanghui Xie
  • Qinying Pan
  • Fengying Zhang
  • Tonu Pullerits
  • Kaibo Zheng

Summary, in English

Photoinduced carrier dynamical processes dominate the optical excitation properties of photocatalysts and further determine the photocatalytic performance. In addition, as the electrons generally possess a faster transfer rate than holes, hole transfer and accumulation are critical, and they play the key efficiency-limiting step during the photocatalytic process. Therefore, a comprehensive understanding of the dynamics of photogenerated holes and their determining factors in the photocatalytic system is highly essential to rationalize the full catalytic mechanism and develop highly efficient photocatalysts, which have not yet been revealed. In this work, the photoinduced charge carrier dynamics in InP/ZnS quantum dots (QDs) capped with long-chain L-typed ligands (oleylamine) and inorganic ligands (sulfide ion (S2−)) were explored. Time-resolved photoluminescence and femtosecond transient-absorption spectroscopy unambiguously confirmed the ultrafast hole transfer from the InP core to S2− ligands. Moreover, by probing the bleach of vibrational stretching of the ligands with transient midinfrared absorption spectroscopy, the hole transfer time was determined to be 4.2 ps. The injected holes are long-lived at the S2− ligands (>4.5 ns), and they can remove electrostatically attached surfactants to compensate for the spatial charge redistribution. Finally, compared with other inorganic ligands such as Cl and PO43−, S2− balances the ionic radii and net charge to ensure the optimal condition for charge transfer. Such observation rationalizes the excellent photocatalytic H2 evolution (213.6 µmol mg−1 within 10 h) in InP/ZnS QDs capped with S2− compared with those capped with other ligands and elucidates the role of surface ligands in the photocatalytic activity of colloidal QDs.

Department/s

  • Chemical Physics
  • NanoLund: Center for Nanoscience
  • eSSENCE: The e-Science Collaboration

Publishing year

2022

Language

English

Publication/Series

SCIENCE CHINA Materials

Document type

Journal article

Publisher

Science in China Press

Topic

  • Physical Sciences

Keywords

  • hole transfer
  • InP/ZnS QD photocatalysts
  • midinfrared spectroscopies
  • surface ligands
  • ultrafast visible spectroscopies

Status

Epub

ISBN/ISSN/Other

  • ISSN: 2095-8226