Oxygen vacancy induced band gap narrowing of ZnO nanostructures by an electrochemically active biofilm

Sajid Ali Ansari, Mohammad Mansoob Khan, Shafeer Kalathil, Ambreen Nisar, Jintae Lee, Moo Hwan Cho*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

453 Citations (Scopus)


Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports a simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the oxygen vacancy and band gap narrowing of m-ZnO. m-ZnO enhanced the visible light catalytic activity for the degradation of different classes of dyes and 4-nitrophenol compared to p-ZnO, which confirmed the band gap narrowing because of oxygen defects. This study shed light on the modification of metal oxide nanostructures by EAB with a controlled band structure.

Original languageEnglish
Pages (from-to)9238-9246
Number of pages9
Issue number19
Publication statusPublished - 7 Oct 2013
Externally publishedYes


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