Simultaneously tuning charge separation and oxygen reduction pathway on graphitic carbon nitride by polyethylenimine for boosted photocatalytic hydrogen peroxide production

Xiangkang Zeng, Yue Liu, Yuan Kang, Qinye Li, Yun Xia, Yinlong Zhu, Huilin Hou, Md Hemayet Uddin, Thomas R. Gengenbach, Dehua Xia, Chenghua Sun, David T. McCarthy, Ana Deletic, Jiaguo Yu, Xiwang Zhang

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)

Abstract

The synthesis of hydrogen peroxide (H2O2) from H2O and O2 by metal-free photocatalysts (e.g., graphitic carbon nitride, C3N4) is a potentially promising approach to generate H2O2. However, the photocatalytic H2O2 generation activity of the pristine C3N4 in pure H2O is poor due to unpropitious rapid charge recombination and unfavorable selectivity. Herein, we report a facile method to boost the photocatalytic H2O2 production by grafting cationic polyethylenimine (PEI) molecules onto C3N4. Experimental results and density functional theory (DFT) calculations demonstrate PEI can tune the local electronic environment of C3N4. The unique intermolecular electronic interaction in PEI/C3N4 not only improves the electron-hole separation but also promotes the two-electron O2 reduction to H2O2 via the sequential two-step single-electron reduction route. With the synergy of improved charge separation and high selectivity of two-electron O2 reduction, PEI/C3N4 exhibits an unexpectedly high H2O2 generation activity of 208.1 μmol g-1 h-1, which is 25-fold higher than that of pristine C3N4. This study establishes a paradigm of tuning the electronic property of C3N4 via functional molecules for boosted photocatalysis activity and selectivity.

Original languageEnglish
Pages (from-to)3697-3706
Number of pages10
JournalACS Catalysis
Volume10
Issue number6
DOIs
Publication statusPublished - 20 Mar 2020

Keywords

  • artificial photosynthesis
  • graphitic carbon nitride
  • hydrogen peroxide
  • intermolecular electron transfer
  • polyethylenimine

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