Creation of Cu2O@TiO2 composite photocatalysts with p - N heterojunctions formed on exposed Cu2O facets, their energy band alignment study, and their enhanced photocatalytic activity under illumination with visible light

Lingmei Liu, Weiyi Yang, Wuzhu Sun, Qi Li, Jian Ku Shang

Research output: Contribution to journalArticlepeer-review

Abstract

The creation of photocatalysts with controlled facets has become an important approach to enhance their activity. However, how the formation of heterojunctions on exposed facets could affect their photocatalytic performance ranking had not yet been investigated. In this study, Cu2O@TiO2 core-shell structures were created, and Cu2O/TiO2 p-n heterojunctions were formed on various exposed facets of Cu2O cubes, Cu2O cuboctahedra, and Cu2O octahedra, respectively. These Cu2O@TiO2 polyhedra demonstrated an enhanced photocatalytic degradation effect on Methylene Blue (MB) and 4-nitrophenol (4-NP) under visible light illumination, because of the enhanced charge carrier separation by the formation of Cu2O@TiO2 p-n heterojunctions. It was further found that their photocatalytic performance was also facet-dependent as pure Cu2O polyhedra, while the photocatalytic performance ranking of these Cu2O@TiO2 polyhedra was different with that of their corresponding Cu2O polyhedron cores. By the combination of optical property measurement and XPS analysis, the energy band alignments of these Cu2O@TiO2 polyhedra were determined, which demonstrated that Cu2O@TiO2 octahedra had the highest band offset for the separation of charge carriers. Thus, the charge-carrier-separation-driven force in Cu2O@TiO2 polyhedra was different from their corresponding Cu2O polyhedron cores, which resulted in their different surface photovoltage spectrum (SPS) responses and different photocatalytic performance rankings.

Original languageEnglish (US)
Pages (from-to)1465-1476
Number of pages12
JournalACS Applied Materials and Interfaces
Volume7
Issue number3
DOIs
StatePublished - Jan 28 2015

Keywords

  • CuO@TiO polyhedra
  • energy band alignment
  • exposed facets
  • p - n heterojunctions
  • visible light photocatalytic activity

ASJC Scopus subject areas

  • Materials Science(all)

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