Humidity sensing properties of ZnO-based fibers by electrospinning

Horzum, Nesrin; Taşçıoglu, Didem; Okur, Salih; Demir, Mustafa M.

doi:10.1016/j.talanta.2011.05.031

Cited by 72 publications

(45 citation statements)

References 36 publications

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“…In the case of electrospinning from an inorganic precursor, the high-temperature calcination process causes a reduction in the diameter of the fibers as the sacrificial polymer template is selectively removed. Consequently, by reason of calcination, the resultant nanofibers become fragile owing to their thinner cross sections and the thermomechanical stress generated from the reduction in size [105,[120][121][122]. There have been many efforts made in recent times towards the production of metal oxide nanofibers by the electrospinning route.…”

Section: Metal Oxide Nanofibersmentioning

confidence: 99%

Recent Advances in the Synthesis of Metal Oxide Nanofibers and Their Environmental Remediation Applications

Mondal

2017

Inventions

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Recently, wastewater treatment by photocatalytic oxidation processes with metal oxide nanomaterials and nanocomposites such as zinc oxide, titanium dioxide, zirconium dioxide, etc. using ultraviolet (UV) and visible light or even solar energy has added massive research importance. This waste removal technique using nanostructured photocatalysts is well known because of its effectiveness in disintegrating and mineralizing the unsafe organic pollutants such as organic pesticides, organohalogens, PAHs (Polycyclic Aromatic Hydrocarbons), surfactants, microorganisms, and other coloring agents in addition to the prospect of utilizing the solar and UV spectrum. The photocatalysts degrade the pollutants using light energy, which creates energetic electron in the metal oxide and thus generates hydroxyl radical, an oxidative mediator that can oxidize completely the organic pollutant in the wastewater. Altering the morphologies of metal oxide photocatalysts in nanoscale can further improve their photodegradation efficiency. Nanoscale features of the photocatalysts promote enhance light absorption and improved photon harvest property by refining the process of charge carrier generation and recombination at the semiconductor surfaces and in that way boost hydroxyl radicals. The literature covering semiconductor nanomaterials and nanocomposite-assisted photocatalysis-and, among those, metal oxide nanofibers-suggest that this is an attractive route for environmental remediation due to their capability of reaching complete mineralization of organic contaminants under mild reaction conditions such as room temperature and ambient atmospheric pressure with greater degradation performance. The main aim of this review is to highlight the most recent published work in the field of metal oxide nanofibrous photocatalyst-mediated degradation of organic pollutants and unsafe microorganisms present in wastewater. Finally, the recycling and reuse of photocatalysts for viable wastewater purification has also been conferred here and the latest examples given.

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Section: Metal Oxide Nanofibersmentioning

confidence: 99%

Recent Advances in the Synthesis of Metal Oxide Nanofibers and Their Environmental Remediation Applications

Mondal

2017

Inventions

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“…28,29 In the electrospinning of inorganic precursor, one has to take into account that the calcination leads almost automatically to a shrinkage of the fibers because the polymer template is removed. After calcination, the nanofibers are usually more brittle 30 because of their thinner section and the internal stress generated by the shrinkage. Therefore, an additional material that is not mechanically or chemically affected by the calcination process needs to be incorporated in the fibers during the electrospinning.…”

Section: ■ Introductionmentioning

confidence: 99%

Hierarchically Structured Metal Oxide/Silica Nanofibers by Colloid Electrospinning

Horzum

Muñoz‐Espí

Glaßer

et al. 2012

ACS Appl. Mater. Interfaces

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We present herein a new concept for the preparation of nanofibrous metal oxides based on the simultaneous electrospinning of metal oxide precursors and silica nanoparticles. Precursor fibers are prepared by electrospinning silica nanoparticles (20 nm in diameter) dispersed in an aqueous solution of poly(acrylic acid) and metal salts. Upon calcination in air, the poly(acrylic acid) matrix is removed, the silica nanoparticles are cemented, and nanocrystalline metal oxide particles of 4−14 nm are nucleated at the surface of the silica nanoparticles. The obtained continuous silica fibers act as a structural framework for metal oxide nanoparticles and show improved mechanical integrity compared to the neat metal oxide fibers. The hierarchically nanostructured materials are promising for catalysis applications, as demonstrated by the successful degradation of a model dye in the presence of the fibers. KEYWORDS: catalysis, ceria, electrospinning, lithium cobalt oxide, metal oxide, nanoparticles ■ INTRODUCTIONBecause of their large ratio of surface area to volume and interconnected porosity, metal oxide meshes have been proposed for applications in catalysis, energy storage, and sensors.1−3 Various bottom-up approachessuch as vapor− liquid−solid (VLS) 4 and vapor−solid (VS) 5 growthand topdown techniquessuch as nanocarving 6 and electrospinning 7 have been described. Among these techniques, electrospinning is probably the most versatile, because it allows the fabrication of fibrous mats from a wide variety of both organic and/or inorganic materials. 8,9 Moreover, it allows for control over the diameter, morphology, porosity, alignment, and composition of the resulting fibers. 10,11Calcination of electrospun mats obtained from metal oxide precursors is a commonly used approach because of its facility and potential for upscaling. The calcination process is usually applied to mixtures of polymers/metal oxide precursors and it is based on an oxidative conversion of the polymeric component by heat treatment. There are many successful examples in literature for the fabrication of inorganic fibers by calcination of precursor materials prepared by sol−gel, 12−18 polymer-based sol−gel processes, 19−22 or from electrospinning of polymer dispersions in the presence of ex situ formed colloids.23−27 Upon increase of the temperature, metal oxide crystals nucleate and grow while the polymeric component undergoes degradation. 28,29 In the electrospinning of inorganic precursor, one has to take into account that the calcination leads almost automatically to a shrinkage of the fibers because the polymer template is removed. After calcination, the nanofibers are usually more brittle 30 because of their thinner section and the internal stress generated by the shrinkage. Therefore, an additional material that is not mechanically or chemically affected by the calcination process needs to be incorporated in the fibers during the electrospinning.The recently reviewed electrospinning of colloids 31 has been explored for the ...

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“…5 Automatic control systems, reliable, cheap and sensitive humidity sensors operated at room temperatures are of significant interest these days. 6 In recent times, the sensors based on porous metal ceramic oxides have received much attention due to their chemical and physical stability. 7 Metal oxide semiconductors nanostructures based sensing devices have perfect chemical reactive surfaces which have excellent water adsorbing and desorbing properties, thermal stabilities, and mechanical durability.…”

Section: Introductionmentioning

confidence: 99%

“…nanoparticles, nanowires, nanorods, nanotetrapods, or nanofibers, and their influence on the humidity sensing performance. 6 Many methods have been employed for the synthesis of oxide nanosturctures e.g. vapour liquid solid (VLS), co-precipitation, hydrothermal synthesis, sol-gel, metalorganic chemical vapour deposition (CVD) and electrospinning.…”

Section: Introductionmentioning

confidence: 99%

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Effect of different electrodes on the transport properties of ZnO nanofibers under humid environment

et al. 2015

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Relative humidity (RH) sensing properties of zinc oxide nanofibers (ZNF), synthesized using electrospinning technique, were studied by impedance spectroscopy. RH sensors were fabricated with two different electrodes (Au and Ni) using lithography on top of the nanofibers deposited on Si/SiO2 substrate. Compare with the Ni electrode sensor, Au electrode sensor exhibits larger sensitivity and quicker response/recovery. Capacitance, electrical conductivity and electrical modulus were studied at 40%-90% RH as a function of the frequency of the applied AC signal in the frequency range of 10−2-106 Hz. The corresponding response and recovery times are 3s and 5s for Au, and 6s and 10s for Ni electrode sensor, respectively. The sensors exhibited a reversible response with small hysteresis of less than 4% and 12% for Au and Ni electrodes respectively. Stability of the sensor device with Au electrode was confirmed by testing the device for 13 days. The excellent sensing characteristics and comparison of sensors with different electrode materials may offer an effective route for designing and optimizing RH sensors.

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Humidity sensing properties of ZnO-based fibers by electrospinning

Cited by 72 publications

References 36 publications

Recent Advances in the Synthesis of Metal Oxide Nanofibers and Their Environmental Remediation Applications

Recent Advances in the Synthesis of Metal Oxide Nanofibers and Their Environmental Remediation Applications

Hierarchically Structured Metal Oxide/Silica Nanofibers by Colloid Electrospinning

Effect of different electrodes on the transport properties of ZnO nanofibers under humid environment

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