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Chemically Modified Metal Oxide Nanostructures Electrodes for Sensing and Energy Conversion
Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The goal of this thesis is the development of scalable, low cost synthesis of metal oxide nanostructures based electrodes and to correlate the chemical modifications with their energy conversion performance. Methods in energy conversion in this thesis have focused on two aspects; a potentiometric chemical sensor was used to determine the analytical concentration of some components of the analyte solution such as dopamine, glucose and glutamate molecules. The second aspect is to fabricate a photo-electrochemical (PEC) cell. The biocompatibility, excellent electro-catalytic activities and fast electron transfer kinetics accompanied with a high surface area to volume ratio; are properties of some metal oxide nanostructures that of a potential for their use in energy conversion. Furthermore, metal oxide nanostructures based electrode can effectively be improved by the physical or a chemical modification of electrode surface. Among these metal oxide nanostructures are cobalt oxide (Co3O4), zinc oxide (ZnO), and bismuth-zincvanadate (BiZn2VO6) have all been studied in this thesis. Metal oxide nanostructures based electrodes are fabricated on gold-coated glass substrate by low temperature (< 100 0C) wet chemicalapproach. X-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption and photoluminescence were used to investigate the optical properties of the nanostructures. The resultant modified electrodes were tested for their performance as chemical sensors and for their efficiency in PEC activities. Efficient chemically modified electrodes were demonstrated through doping with organic additives like anionic, nonionic or cationic surfactants. The organic additives are showing a crucial role in the growth process of metal oxide nanocrystals and hence can beused to control the morphology. These organic additives act also as impurities that would significantly change the conductivity of the electrodes. However, no organic compounds dependence was observed to modify the crystallographic structure. The findings in this thesis indicate the importance of the use of controlled nanostructures morphology for developing efficient functional materials.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017. , p. 73
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1827
Keywords [en]
Metal oxide nanostructures, mixed metal oxide nano-compound, low temperature wet-chemical growth, chemically modified electrode, doping, surfactant, potentiometric sensor, chemical sensor and photo-electrochemical activity
National Category
Materials Chemistry Inorganic Chemistry Other Chemical Engineering Analytical Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-134275DOI: 10.3384/diss.diva-134275ISBN: 9789176855904 (print)OAI: oai:DiVA.org:liu-134275DiVA, id: diva2:1070790
Public defence
2017-03-03, Sal K3, Kåkenhus, Campus Norrköping, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2017-02-02 Created: 2017-02-02 Last updated: 2017-02-09Bibliographically approved
List of papers
1. Incorporating beta-Cyclodextrin with ZnO Nanorods: A Potentiometric Strategy for Selectivity and Detection of Dopamine
Open this publication in new window or tab >>Incorporating beta-Cyclodextrin with ZnO Nanorods: A Potentiometric Strategy for Selectivity and Detection of Dopamine
2014 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 1, p. 1654-1664Article in journal (Refereed) Published
Abstract [en]

We describe a chemical sensor based on a simple synthesis of zinc oxide nanorods (ZNRs) for the detection of dopamine molecules by a potentiometric approach. The polar nature of dopamine leads to a change of surface charges on the ZNR surface via metal ligand bond formation which results in a measurable electrical signal. ZNRs were grown on a gold-coated glass substrate by a low temperature aqueous chemical growth (ACG) method. Polymeric membranes incorporating beta-cyclodextrin (beta-CD) and potassium tetrakis (4-chlorophenyl) borate was immobilized on the ZNR surface. The fabricated electrodes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The grown ZNRs were well aligned and exhibited good crystal quality. The present sensor system displays a stable potential response for the detection of dopamine in 10(-2) mol.L-1 acetic acid/sodium acetate buffer solution at pH 5.45 within a wide concentration range of 1 x 10(-6) M-1 x 10(-1) M, with sensitivity of 49 mV/decade. The electrode shows a good response time (less than 10 s) and excellent repeatability. This finding can contribute to routine analysis in laboratories studying the neuropharmacology of catecholamines. Moreover, the metal-ligand bonds can be further exploited to detect DA receptors, and for bio-imaging applications.

Place, publisher, year, edition, pages
MDPI, 2014
Keywords
ZnO nanorods; dopamine; potentiometric response; selectivity; stability; repeatability
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107470 (URN)10.3390/s140101654 (DOI)000336039100087 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
2. Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
Open this publication in new window or tab >>Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
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2015 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 116, p. 21-26Article in journal (Refereed) Published
Abstract [en]

Generally, the anisotropic shape of inorganic nano-crystal can be influenced by one or more of different parameters i.e. kinetic energy barrier, temperature, time, and the nature of the capping molecules. Here, different surfactants acting as capping molecules were used to assist the aqueous chemical growth of zinc oxide (ZnO) nanostructures on Au coated glass substrates. The morphology, crystal quality and the photoluminescence (PL) properties of the ZnO nanostructures were investigated. The PL properties of the prepared ZnO nanostructures at room temperature showed a dominant UV luminescence peak, while the "green yellow" emissions were essentially suppressed. Moreover, the ZnO nanostructures were investigated for the development of a glucose biosensor. An adsorbed molecule has direct contribution on the glucose oxidase/ZnO/Au sensing properties. We show that the performance of a ZnO-based biosensor can be improved by tailoring the properties of the ZnO biomolecule interface through engineering of the morphology, effective surface area, and adsorption capability.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
ZnO nanostructures; Cationic and anionic molecules; PL spectra; Glucose sensitivity
National Category
Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-119245 (URN)10.1016/j.vacuum.2015.02.026 (DOI)000354582900004 ()
Note

Funding Agencies|University of Kordofan Grant, El-Obeid, Kordofan Sudan [700]

Available from: 2015-06-15 Created: 2015-06-12 Last updated: 2017-12-04
3. Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor
Open this publication in new window or tab >>Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor
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2014 (English)In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 26, no 8, p. 1773-1781Article in journal (Refereed) Published
Abstract [en]

In this study, an effect of different concentrations of urea on the morphology of cobalt oxide (Co3O4) nanostructures was investigated. The Co3O4 nanostructures are fabricated on gold coated glass substrate by the hydrothermal method. The morphological and structural characterization was performed by scanning electron microscopy, and X-ray diffraction techniques. The Co3O4 nanostructures exhibit morphology of flowers-like and have comprised on nanowires due to the increasing amount of urea. The nanostructures were highly dense on the substrate and possess a good crystalline quality. The Co3O4 nanostructures were successfully used for the development of a sensitive glucose biosensor. The presented glucose biosensor detected a wide range of glucose concentrations from 1 x 10(-6) M to 1 x 10(-2) M with sensitivity of a -56.85 mV/decade and indicated a fast response time of less than 10 s. This performance could be attributed to the heterogeneous catalysis effect at glucose oxidase enzyme, nanoflowers, and nanowires interfaces, which have enhanced the electron transfer process on the electrode surface. Moreover, the reproducibility, repeatability, stability and selectivity were also investigated. All the obtained results indicate the potential use of the developed glucose sensor for monitoring of glucose concentrations at drugs, human serum and food industry related samples.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2014
Keywords
Nanostructures; Hydrothermal method; Glucose biosensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-110486 (URN)10.1002/elan.201400116 (DOI)000340557700016 ()
Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2017-12-05Bibliographically approved
4. Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode
Open this publication in new window or tab >>Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode
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2014 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 203, p. 543-549Article in journal (Refereed) Published
Abstract [en]

Ultra-thin cobalt oxide (Co3O4) nanowires grown on gold coated glass substrates by the hydrothermal chemical deposition and have been used as a wide range dopamine potentiometric sensor. An anionic surfactant ( sodium dodecylbenzenesulfonate) was used to achieve assisted growth procedure. Moreover, a polymeric membrane containing polyvinyl chloride as plasticized polymer, p-cyclodextrin as ionophore, and potassium tetrakis (4-chlorophenyl) borate as ionic additive were immobilized on the Co3O4 nanostructures through electrostatic adsorption method. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption was used to investigate the band gap of the Co3O4 nanostructures. The structural characterization showed a cubic crystalline, pure phase, and nanowires morphology of the Co3O4. However, the morphology is altered when the surfactant concentration has been changed. The Co3O4 chemical modified electrodes were used in potentiometric measurements for dopamine in a 10(-2) M acetic acid/sodium acetate solution having a pH of 5.45. For dopamine range from 10(-9) M to 10(-2) M, the potential response of the sensor electrode was linear with a slope of 52 mV/decade. The wide range and high sensitivity of the modified Co3O4 nanowires based sensor for dopamine is attributed to the defects on the metal oxide that is dictated by the used surfactant along with the high surface area-to-volume ratio.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Potentiometric sensor; Chemically modified electrode; Surfactant; Dopamine chemical sensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
Identifiers
urn:nbn:se:liu:diva-111254 (URN)10.1016/j.snb.2014.07.028 (DOI)000341455400072 ()
Available from: 2014-10-15 Created: 2014-10-14 Last updated: 2017-12-05Bibliographically approved
5. Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
Open this publication in new window or tab >>Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
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2016 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed) Published
Abstract [en]

In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

Place, publisher, year, edition, pages
MDPI AG, 2016
Keywords
potentiometric sensor; ZnO nanorods; glutamate; doping
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-126849 (URN)10.3390/s16020222 (DOI)000371787800096 ()26861342 (PubMedID)
Note

Funding Agencies|University of Kordofan, El-Obeid, Kordofan Sudan [700]

Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2017-11-30
6. Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
Open this publication in new window or tab >>Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
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2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 3, p. 1112-1119Article in journal (Refereed) Published
Abstract [en]

We demonstrate scalable, low-cost and low-temperature (<100 °C) aqueous chemical growth of bismuth–zinc vanadate (BiZn2VO6) nanocompounds by BiVO4 growth on ZnO nanobelts (NBs). The nanocompounds were further doped with polyethylene glycol (PEG) to tune the electronic structure of the materials, as a means to lower the charge carrier recombination rate. The chemical composition, morphology, and detailed nanostructure of the BiZn2VO6 nanocompounds were characterized. They exhibit rice-like morphology, are highly dense on the substrate and possess a good crystalline quality. Photoelectrochemical characterization in 0.1 M lithium perchlorate in carbonate propylene shows that BiZn2VO6 nanocompounds are highly suitable as anodes for solar-driven photoelectrochemical applications, providing significantly better performance than with only ZnO NBs. This performance could be attributed to the heterogeneous catalysis effect at nanocompound and ZnO NB interfaces, which have enhanced the electron transfer process on the electrode surface. Furthermore, the charge collection efficiency could be significantly improved through PEG doping of nanocompounds. The photocurrent density of PEG-doped BiZn2VO6 nanocompounds reached values of 2 mA cm−2 at 1.23 V (vs. Ag/AgCl), over 60% larger than that of undoped BiZn2VO6 nanocompounds. Photoluminescence emission experiments confirmed that PEG plays a crucial role in lowering the charge carrier recombination rate. The presented BiZn2VO6 nanocompounds are shown to provide highly competitive performance compared with other state-of-the art photoelectrodes.

Place, publisher, year, edition, pages
Cambridge: Royal Society of Chemistry, 2017
National Category
Materials Chemistry Condensed Matter Physics Inorganic Chemistry Ceramics
Identifiers
urn:nbn:se:liu:diva-134273 (URN)10.1039/C6TA10180A (DOI)000394430800031 ()
Note

Funding agencies:  Ministry of Higher Education and Scientific Research, Khartoum-Sudan [700]; Wenner-Gren Foundations; Swedish Government Strategic Research Area in Materials Science on Functional Material at Linkoping University [2009 00971]; Swedish Foundation for Strate

Available from: 2017-02-02 Created: 2017-02-02 Last updated: 2017-11-29Bibliographically approved

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