Oxygen defects-mediated Z-scheme charge separation in g-C3N4/ZnO photocatalysts for enhanced visible-light degradation of 4-chlorophenol and hydrogen evolution

Jing Wang, Yi Xia, Hongyuan Zhao, Guifang Wang, Lan Xiang, Jianlong Xu, Sridhar Komarneni

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g-C3N4nanosheets were coupled with oxygen-defective ZnO nanorods (OD-ZnO) to form a heterojunction photocatalyst with a core-shell structure. Multiple optical and electrochemical analysis including electrochemical impedance spectroscopy, photocurrent response and steady/transient photoluminescence spectroscopy revealed that the g-C3N4/OD-ZnO heterojunction exhibited increased visible-light absorption, improved charge generation/separation efficiency as well as prolonged lifetime, leading to the enhanced photocatalytic activities for the degradation of 4-chlorophenol under visible-light illumination (λ > 420 nm). An oxygen defects-mediated Z-scheme mechanism was proposed for the charge separation in the heterojunction, which involved the recombining of photoinduced electrons that were trapped in the oxygen defects-level of OD-ZnO directly with the holes in the valence band of g-C3N4at the heterojunction interface. The detection of surface generated reactive species including [rad]O2and [rad]OH clearly supported the Z-scheme mechanism. Moreover, the g-C3N4/OD-ZnO photocatalysts also exhibited enhanced visible-light Z-scheme H2evolution activity, with an optimal H2evolution rate of about 5 times than that of pure g-C3N4. The present work not only provided an alternative strategy for construction of novel visible-light-driven Z-scheme photocatalysts, but also gained some new insights into the role of oxygen-defects of semiconductors in mediating the Z-scheme charge separation.

Original languageEnglish (US)
Pages (from-to)406-416
Number of pages11
JournalApplied Catalysis B: Environmental
StatePublished - 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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