Enhanced visible light photocatalytic activity and oxidation ability of porous graphene-like g-C₃N₄ nanosheets via thermal exfoliation

Fan DONG, Yuhan LI, Zhenyu WANG, Wing Kei HO

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192 Citations (Scopus)

Abstract

Graphene-like porous g-C₃N₄ nanosheets were synthesized via direct pyrolysis of thiourea followed by a thermal exfoliation. With increased exfoliation temperature, the color of the resulting samples gradually became shallow, and the thickness and size of the layers were decreased. A formation mechanism involving layer-by-layer exfoliation coupled with layer splitting was proposed. The band structure of the g-C₃N₄ nanosheets was continuously tuned because of quantum size effect. Time-resolved decay spectra indicated that the radiative lifetime of charge carriers (τ1 and τ2) increased from 4.13 and 26.23 ns for bulk g-C₃N₄ to 5.36 and 36.57 ns for graphene-like g-C3N4 nanosheets. The g-C₃N₄ nanosheet samples were applied for visible light photocatalytic removal of NOx in air. The performance of porous g-C₃N₄ nanosheets was significantly enhanced with increased exfoliation temperature from 450 to 550 °C. Moreover, photochemical and structural stability was well maintained after multiple reaction cycles. By monitoring the reaction intermediate NO₂, it was found that the generation of NO₂ was inhibited. The activity enhancement of graphene-like g-C₃N₄ nanosheets can be predominantly ascribed to the prolonged lifetime and improved photo-oxidation ability of charge carriers arising from the unique electronic structure. As the synthesis method for graphene-like g-C₃N₄ nanosheets with high a performance is simple, the g-C₃N₄ nanosheets can be envisioned to be applicable in environmental remediation and solar energy conversion. © 2015 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)393-403
JournalApplied Surface Science
Volume358
Issue numberPart A
DOIs
Publication statusPublished - Apr 2015

Citation

Dong, F., Li, Y., Wang, Z., & Ho, W.-K. (2015). Enhanced visible light photocatalytic activity and oxidation ability of porous graphene-like g-C₃N₄ nanosheets via thermal exfoliation. Applied Surface Science, 358(Part A), 393-403. doi: 10.1016/j.apsusc.2015.04.034

Keywords

  • Porous g-C₃N₄ nanosheets
  • Thermal exfoliation
  • Band structure
  • Visible light photocatalysis
  • Oxidation ability

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