Journal
APPLIED CATALYSIS B-ENVIRONMENTAL
Volume 206, Issue -, Pages 406-416Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apcatb.2017.01.067
Keywords
g-C3N4/OD-ZnO catalyst; Z-scheme charge separation; Degradation of 4-chlorophenol; H-2 evolution; Heterojunction interface
Funding
- National Science Foundation of China [51234003, 51374138]
- National Science Foundation of Jiangsu Province [BK20160328]
- National Key Technology Research and Development Program of China [2013BAC14B02]
- China Scholarship Council [201506210232]
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g-C3N4 nanosheets 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 (lambda > 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-C3N4 at the heterojunction interface. The detection of surface generated reactive species including O-center dot(2-) and (OH)-O-center dot clearly supported the Z-scheme mechanism. Moreover, the g-C3(N4)/OD-ZnO photocatalysts also exhibited enhanced visible-light Z-scheme H-2 evolution activity, with an optimal H-2 evolution 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. (C) 2017 Elsevier B.V. All rights reserved.
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