Thermal diffusion of Co into sputtered ZnO:Co thin film for enhancing visible-light-induced photo-catalytic activity

Chi Yuan Kao, Jiunn Der Liao, Chia Wei Chang, Ru Yang Wang

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

ZnO has received a lot of attention in for the degradation and complete mineralization of environmental pollutants. In this study, efficient ZnO-based visible-light photocatalysts are synthesized via a low-cost method by increasing the Co concentration at the outermost surface of ZnO:Co thin film under an annealing process. The simply adjusted Co concentration gradient (≈1.5% increase) into the surface of ZnO:Co is driven by thermal diffusion. Co ions substitute Zn sites in the ZnO lattice. The band gap narrowed due to sp-d exchange interactions between the conduction band electrons and the d electrons of Co. The annealing process enhances the grain size and the degree of crystallinity of the diffused Co/ZnO:Co, which contributes to the absorption edge red-shift. Photocatalytic activities such as the photo-degradation of methylene blue and the inactivation of bacteria are obviously enhanced. The proposed low-cost method significantly increases the efficiency of ZnO for the generation of the photocatalytic effect under visible-light exposure.

Original languageEnglish
Pages (from-to)1813-1818
Number of pages6
JournalApplied Surface Science
Volume258
Issue number5
DOIs
Publication statusPublished - 2011 Dec 15

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Thermal diffusion
Catalyst activity
Annealing
Thin films
Environmental Pollutants
Electrons
Methylene Blue
Exchange interactions
Photodegradation
Photocatalysts
Conduction bands
Costs
Bacteria
Energy gap
Ions
Degradation

All Science Journal Classification (ASJC) codes

  • Surfaces, Coatings and Films

Cite this

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abstract = "ZnO has received a lot of attention in for the degradation and complete mineralization of environmental pollutants. In this study, efficient ZnO-based visible-light photocatalysts are synthesized via a low-cost method by increasing the Co concentration at the outermost surface of ZnO:Co thin film under an annealing process. The simply adjusted Co concentration gradient (≈1.5{\%} increase) into the surface of ZnO:Co is driven by thermal diffusion. Co ions substitute Zn sites in the ZnO lattice. The band gap narrowed due to sp-d exchange interactions between the conduction band electrons and the d electrons of Co. The annealing process enhances the grain size and the degree of crystallinity of the diffused Co/ZnO:Co, which contributes to the absorption edge red-shift. Photocatalytic activities such as the photo-degradation of methylene blue and the inactivation of bacteria are obviously enhanced. The proposed low-cost method significantly increases the efficiency of ZnO for the generation of the photocatalytic effect under visible-light exposure.",
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Thermal diffusion of Co into sputtered ZnO:Co thin film for enhancing visible-light-induced photo-catalytic activity. / Kao, Chi Yuan; Liao, Jiunn Der; Chang, Chia Wei; Wang, Ru Yang.

In: Applied Surface Science, Vol. 258, No. 5, 15.12.2011, p. 1813-1818.

Research output: Contribution to journalArticle

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