Facet-Dependent Photocatalytic Behaviors of ZnS-Decorated Cu 2 O Polyhedra Arising from Tunable Interfacial Band Alignment

Gollapally Naresh, Pei Lun Hsieh, Vandana Meena, Shih Kuang Lee, Yi Hsuan Chiu, Mahesh Madasu, An Ting Lee, Hsin Yi Tsai, Ting Hsuan Lai, Yung-Jung Hsu, Yu-Chieh Lo*, Michael H. Huang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

ZnS particles were grown over Cu 2 O cubes, octahedra, and rhombic dodecahedra for examination of their facet-dependent photocatalytic behaviors. After ZnS growth, Cu 2 O cubes stay photocatalytically inactive. ZnS-decorated Cu 2 O octahedra show enhanced photocatalytic activity, resulting from better charge carrier separation upon photoexcitation. Surprisingly, Cu 2 O rhombic dodecahedra give greatly suppressed photocatalytic activity after ZnS deposition. Electron paramagnetic resonance spectra agree with these experimental observations. Time-resolved photoluminescence profiles provide charge-transfer insights. The decrease in the photocatalytic activity is attributed to an unfavorable band alignment caused by significant band bending within the Cu 2 O(110)/ZnS(200) plane interface. A modified Cu 2 O-ZnS band diagram is presented. Density functional theory calculations generating plane-specific band energy diagrams of Cu 2 O and ZnS match well with the experimental results, showing that charge transfer across the Cu 2 O(110)/ZnS(200) plane interface would not happen. This example further illustrates that the actual photocatalysis outcome for semiconductor heterojunctions cannot be assumed because interfacial charge transfer is strongly facet-dependent.

Original languageEnglish
Pages (from-to)3582-3589
Number of pages8
JournalACS Applied Materials and Interfaces
Volume11
Issue number3
DOIs
StatePublished - 23 Jan 2019

Keywords

  • band alignment
  • cuprous oxide
  • facet-dependent properties
  • heterojunctions
  • interfacial charge transfer
  • zinc sulfide

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