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Synthesis and Characterization of CuO/ZnO Composite Nanostructures: Precursor’s Effects, and their Optical Properties
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
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2012 (English)Manuscript (preprint) (Other academic)
Abstract [en]

A two steps hydrothermal method was developed to synthesize CuO/ZnO composite nanostructures (NSs) on glass substrate. The CuO NSs were selectively assembled on the lateral surface of ZnO nanorods (NRs) upon short growth duration. While the CuO NSs were entirely covered the surface of ZnO NRs at extended growth durations. The growth kinetics of CuO NSs is strongly dependent on the nature and the pH value of the precursor solution. When a single precursor solution of copper nitrate was applied in the synthesis process, a coral-like CuO/ZnO NSs were obtained. However, by adding a pH controlling agent to the precursor solution significant increase in the size of the grown CuO NSs was observed. The results revealed that the grown CuO NSs were robustly adhered to ZnO NRs, however, no explicit epitaxial relationship was found. The ZnO NRs band to band and defects emissions ratio was decreased compared to that of pure ZnO NRs, suggesting that oxygen vacancies are the probable growth sites of CuO NSs. The CuO/ZnO composite NSs exhibited a broad light absorption covering the whole visible range compared to the constituent materials. The low growth temperatures along with the optical properties of CuO/ZnO suggest these composite NSs may carry great potentials in light harvesting, sensing and emitting applications.

Place, publisher, year, edition, pages
2012.
Keyword [en]
Hydrothermal, ZnO nanorods, CuO nanostructures, deep level defects, composite
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-81428OAI: oai:DiVA.org:liu-81428DiVA: diva2:552410
Available from: 2012-09-14 Created: 2012-09-14 Last updated: 2014-01-15Bibliographically approved
In thesis
1. Synthesis of ZnO, CuO and their Composite Nanostructures for Optoelectronics, Sensing and Catalytic Applications
Open this publication in new window or tab >>Synthesis of ZnO, CuO and their Composite Nanostructures for Optoelectronics, Sensing and Catalytic Applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Research on nanomaterials has become increasingly popular because of their unique physical, chemical, optical and catalytic properties compared to their bulk counterparts. Therefore, many efforts have been made to synthesize multidimensional nanostructures for new and efficient nanodevices. Among those materials, zinc oxide (ZnO), has gained substantial attention owing to many outstanding properties. ZnO besides its wide bandgap of 3.34 eV exhibits a relatively large exciton binding energy (60 meV) at room temperature which is attractive for optoelectronic applications. Likewise, cupric oxide (CuO), having a narrow band gap of 1.2 eV and a variety of chemo-physical properties that are attractive in many fields. Moreover, composite nanostructures of these two oxides (CuO/ZnO) may pave the way for various new applications.

This thesis can be divided into three parts concerning the synthesis, characterization and applications of ZnO, CuO and their composite nanostructures.

In the first part the synthesis, characterization and the fabrication of ZnO nanorods based hybrid light emitting diodes (LEDs) are discussed. The low temperature chemical growth method was used to synthesize ZnO nanorods on different substrates, specifically on flexible non-crystalline substrates. Hybrid LEDs based on ZnO nanorods combined with p-type polymers were fabricated at low temperature to examine the advantage of both materials. A single and blended light emissive polymers layer was studied for controlling the quality of the emitted white light.

The second part deals with the synthesis of CuO nanostructures (NSs) which were then used to fabricate pH sensors and exploit these NSs as a catalyst for degradation of organic dyes. The fabricated pH sensor exhibited a linear response and good potential stability. Furthermore, the catalytic properties of petals and flowers like CuO NSs in the degradation of organic dyes were studied. The results showed that the catalytic reactivity of the CuO is strongly depending on its shape.

In the third part, an attempt to combine the advantages of both ZnO and CuO NSs was performed by developing a two-step chemical growth method to synthesize the composite NSs. The synthesized CuO/ZnO composite NSs revealed an extended light absorption and enhanced defect related visible emission.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. 59 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1467
Keyword
ZnO, CuO, Nanostructures, Low temperature growth, Light emitting diodes, pH sensors
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-81120 (URN)978-91-7519-818-7 (ISBN)
Public defence
2012-09-28, K3, Kåkenhus, Campus Norrköping, Linköping University, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2012-09-07 Created: 2012-09-07 Last updated: 2014-01-15Bibliographically approved
2. Lighting and Sensing Applications of Nanostructured ZnO, CuO and Their Composites
Open this publication in new window or tab >>Lighting and Sensing Applications of Nanostructured ZnO, CuO and Their Composites
2012 (English)Doctoral thesis, comprehensive summary (Other academic) [Artistic work]
Abstract [en]

Low dimensional nanostructures of zinc oxide (ZnO), cupric oxide (CuO), and their composite nanostructures possess remarkable physical and chemical properties. Fundamental understanding and manipulation of these unique properties are crucial for all potential applications. Integration of nanostructured ZnO and CuO and their hybrid composites may play a significant role in the existing technology while paving the way for new exciting areas. Solution based low temperature synthesis of ZnO and CuO nanostructures have attracted extensive research efforts during the last decade. These efforts resulted in a plenteous number of nanostructures ranging from quantum dots into very complex three dimensional nanomaterials. Among the various low temperature synthesis methods the hydrothermal technique became one of the most popular approaches. The use of hydrothermal approach enabled the synthesis of diversity of nanomaterials on conventional and nonconventional substrates such as metals, glass, plastic and paper etc.

The primary objectives of this thesis are to study and understand the characteristics of nanostructured ZnO, CuO, and their hybrid composites synthesized at low temperature. Likewise, the hybrid composites were successfully utilized to fabricate light emitting diodes and sensors. This thesis is organized into three major parts. In the beginning the synthesis and characterization of nanostructured ZnO, CuO, and their composite nanostructures are elaborated. Efforts have been made to understand the selective assembly of hierarchical CuO nanostructures on ZnO nanorods and to correlate it to the observed unique properties of the CuO/ZnO composite nanostructures. In the second part of the thesis fabrication, characterization, and device application of ZnO/p-polymer hybrid light emitting diode (HyLEDs) on flexible substrates are presented. In particular single and blended p-type light emissive polymers were controllably developed for potential greener and cheaper white light emitters. It was found that the HyLEDs exhibited rectifying diode characteristics together with white light emission covering the entire visible range. In the third part, pH and relative humidity sensing applications of CuO nanoflowers, and CuO/ZnO nanocorals, respectively, are described. A pH sensor based on CuO nanoflowers demonstrated good sensitivity and reproducibility over a wide range of pH. By taking the advantages of the selective growth of CuO nanostructures on ZnO nanorods and their naturally formed p-n heterojunction the realization of high sensitivity humidity sensor was achieved. The humidity sensor fabricated from the CuO/ZnO nanocorals displayed the highest sensitivity factor reported so far for its constituent materials; along with reasonably fast dynamic responses. A brief outlook into future challenges and opportunities are also presented in the last part of the thesis. 

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. 79 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1484
Keyword
ZnO, CuO, Nanostructures, Composites, ZnO/polymer LEDs, humidity sensor, p-n heterojunction
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85111 (URN)978-91-7519-755-5 (ISBN)
Public defence
2012-12-06, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:00 (English)
Opponent
Supervisors
Projects
Nanophotonics
Available from: 2012-11-27 Created: 2012-11-05 Last updated: 2017-02-23Bibliographically approved

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