Nitrogen-Doped Graphene Quantum Dots for Remarkable Solar Hydrogen Production

Kai An Tsai, Ping Yen Hsieh, Ting Hsuan Lai, Chun Wen Tsao, Hui Pan, Yan Gu Lin, Yung-Jung Hsu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We synthesized nitrogen (N)-doped graphene quantum dots (N-GQDs) using a top-down hydrothermal cutting approach. The concentration of N dopants was readily controlled by adjusting the concentration of the N source of urea. When N dopants were incorporated into GQDs, visible absorption was induced by C-N bonds, which created another pathway for generating photoluminescence (PL). Time-resolved PL data revealed that the carrier lifetime of GQDs was increased upon doping with the optimized N concentration. The photoelectrochemical properties of N-GQDs toward water splitting were studied, and the results showed that 2N-GQDs prepared with 2 g of urea produced the highest photocurrent. The photocatalytic activity of 2N-GQDs powder photocatalyst for hydrogen production was also examined under AM 1.5G illumination, showing substantial enhancement over that of pristine GQDs. Electrochemical impedance spectroscopy data further revealed a significant improvement in charge dynamics and reaction kinetics and an increased carrier concentration as a result of N doping.

Original languageEnglish
Pages (from-to)5322-5332
Number of pages11
JournalACS Applied Energy Materials
Issue number6
StatePublished - 22 Jun 2020


  • charge dynamics
  • graphene quantum dots
  • nitrogen-doped
  • solar hydrogen production
  • water splitting


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