Synergistic effect of oxygen and nitrogen functionalities for graphene-based quantum dots used in photocatalytic H2 production from water decomposition

Te Fu Yeh, Shean-Jen Chen, Hsisheng Teng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

94 Scopus citations

Abstract

Surface intact nitrogen-doped graphene oxide quantum dots (iNGO-QDs), which are based on the abundant elements C, H, O, and N, exhibit outstanding photocatalytic performance in H2 production through water decomposition. In this study, we synthesize the iNGO-QDs by thermally treating graphene oxide sheets in NH3 with subsequent ultrasonic exfoliation. The iNGO-QDs exhibit sizes of 2 to 6nm and consist of approximately 3 graphitic layers. Nitrogen doping in QD synthesis repairs the vacancy-type defects of GO and introduces n-type conductivity to compensate for the unbalanced charges on p-type GO, thereby suppressing leaks of photogenerated charges. Coexistence of p- and n-domains in the iNGO-QDs may form photochemical diodes to facilitate charge separation. Under visible light illumination, the iNGO-QDs steadily catalyze the production of H2 from an aqueous solution containing triethanolamine. When deposited with Pt as the cocatalyst, the iNGO-QDs exhibit high activity in H2 generation at an apparent quantum yield of 12.8% under monochromatic light (420nm) irradiation. The high activity of the iNGO-QDs can be attributed to the synergistic effect of the oxygen and nitrogen functionalities in facilitating charge separation and transfer.

Original languageEnglish
Pages (from-to)476-485
Number of pages10
JournalNano Energy
Volume12
DOIs
StatePublished - 1 Mar 2015

Keywords

  • Graphene oxide
  • Graphene quantum dot
  • Hydrogen production
  • Photocatalysis
  • Photosynthesis
  • Water-splitting

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