Fabrication of hydrogen sensors with transparent titanium oxide nanotube-array thin films as sensing elements

Mor, Gopal K.; Varghese, Oomman K.; Paulose, Maggie; Ong, Keat Ghee; Grimes, Craig A.

doi:10.1016/j.tsf.2005.08.190

Cited by 208 publications

(128 citation statements)

References 26 publications

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“…The increased thickness of nanotube walls should be a consequence of using the lower anodization temperature. Although the formation of TiO 2 nanotubes is a result of the competition between the electrochemical etching of Ti and the chemical dissolution of TiO 2 occurring in the electrolyte solution during anodization [16], the chemical dissolution would be a limiting factor for the growth of nanotube length and wall, depending on the solution temperature.…”

Section: Morphology Of Tnt Filmsmentioning

confidence: 99%

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Liang

2009

Journal of Hazardous Materials

179

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In this study titanium dioxide nanotube (TNT) arrays were prepared by an anodic oxidation process with post-calcination. The morphology and structure of the TNT films were studied by FESEM, XRD, and XPS. Photocatalytic activity of the TNT films was evaluated in terms of the degradation of 2,3-dichlorophenol in aqueous solution under UV light irradiation. The effects of the nanotube structure including tube length and tube wall thickness, and crystallinity on the photocatalytic activity were investigated in details. The results showed that the large specific surface area, high pore volume, thin tube wall, and optimal tube length would be important factors to achieve the good performance of TNT films. Moreover, the TNT films calcined at 500 o C for 1 h with the higher degree of crystallinity exhibited the higher photocatalytic activity than other TNT films calcined at 300 o C and 800 o C. Consequently, these results indicate that the optimization of TiO 2 nanotube structures is critical to achieve the high performance of photocatalytic reaction.

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Section: Morphology Of Tnt Filmsmentioning

confidence: 99%

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Liang

2009

Journal of Hazardous Materials

179

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“…[39][40][41] All samples were crystallized and treated with aqueous TiCl 4 solution under identical conditions. A cross-sectional FESEM view of a TiCl 4 treated nanotube array film (length ∼1 to 1.2 µm) is shown in Figure 3a.…”

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confidence: 99%

Visible to Near-Infrared Light Harvesting in TiO₂ Nanotube Array−P3HT Based Heterojunction Solar Cells

et al. 2009

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The development of high-efficiency solid-state excitonic photovoltaic solar cells compatible with solution processing techniques is a research area of intense interest, with the poor optical harvesting in the red and near-IR (NIR) portion of the solar spectrum a significant limitation to device performance. Herein we present a solid-state solar cell design, consisting of TiO 2 nanotube arrays vertically oriented from the FTOcoated glass substrate, sensitized with unsymmetrical squaraine dye (SQ-1) that absorbs in the red and NIR portion of solar spectrum, and which are uniformly infiltrated with p-type regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) that absorbs higher energy photons. Our solidstate solar cells exhibit broad, near-UV to NIR, spectral response with external quantum yields of up to 65%. Under UV filtered AM 1.5G of 90 mW/cm 2 intensity we achieve typical device photoconversion efficiencies of 3.2%, with champion device efficiencies of 3.8%.The best performing bulk heterojunction solar cells (η ∼ 6%) employ an optimized blend of a polymeric donor and a fullerene acceptor. 1,2 The fullerene acceptor absorbs very little light and is primarily used in blends to provide an efficient interface for exciton dissociation. Various efforts toward efficiency improvement in these devices are directed toward the development of low band gap polymers to absorb a broad swathe of the solar spectrum, 3-6 lowering the molecular energy levels of the semiconducting polymer to enhance the open circuit voltage of the organic solar cells, 1,7 and the control of the blended film morphology for enhanced exciton harvesting. [8][9][10][11][12] In the best performing solid-state dyesensitized solar cells (SS-DSSCs), η ∼ 5%, the only photon absorber is a dye, while the electron and hole transport functions are performed, respectively, by a disordered nanoparticulate TiO 2 network and a transparent small molecule spiro-OMeTAD. [13][14][15][16] To achieve higher efficiency devices, research efforts have focused on improved porefilling by the hole transporter, the use of higher mobility hole transporters and the synthesis of dyes with a broader and more-intense absorption spectrum.Red/NIR radiation (650-1000 nm) accounts for approximately 33% of the solar energy arriving at the surface of the Earth, while UV-visible radiation (350-650 nm) accounts for about 40%. Hence a key issue toward achieving higher efficiency organic solar cells is in the development of red and NIR absorbing molecules to utilize more of the solar spectrum. As an approach for efficiently utilizing visible to NIR solar radiation, herein we describe an inorganic-organic hybrid solar cell, see Figure 1a, where electron transporting TiO 2 nanotube arrays, sensitized with red and NIR light absorbing organic dye, are used in combination with hole transporting and visible light absorbing regioregular P3HT. [17][18][19] It should be noted that this low band gap organic dye should not block transmission of the high-energy photons of near-UV-visible range pa...

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“…Commercially, hydrogen sensors are mainly composed of metal oxide (e.g., SnO 2 ) films based on the chemresistive mechanism. [3][4][5][6][7] However, to obtain satisfactory results by using metal oxide sensors a temperature over 400 1C is usually required, 8 which is energy intensive and may trigger an explosion. Therefore, it is desirable to develop new types of hydrogen sensors which operate at room temperature.…”

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confidence: 99%

Enhanced hydrogen sensing properties of graphene by introducing a mono-atom-vacancy

Jiang

Zheng

et al. 2013

Phys. Chem. Chem. Phys.

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aTo facilitate the dissociative adsorption of H 2 molecules on pristine graphene, the addition of a monoatom-vacancy to graphene is proposed. This leads to reduction of the dissociative energy barrier for a H 2 molecule on graphene from 3.097 to 0.805 eV for the first H 2 and 0.869 eV for the second, according to first principles calculations. As a result, two H 2 molecules can be easily dissociatively adsorbed on this defected graphene at room temperature. The electronic structure and conductivity of the graphene change significantly after H 2 adsorption. In addition, the related dissociative adsorption phase diagrams under different temperatures and partial pressures show that this dissociative adsorption at room temperature is very sensitive (10 À35 mol L À1 ). Therefore, this defected graphene is promising for ultra-sensitive room temperature hydrogen sensing.

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Fabrication of hydrogen sensors with transparent titanium oxide nanotube-array thin films as sensing elements

Cited by 208 publications

References 26 publications

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Visible to Near-Infrared Light Harvesting in TiO₂ Nanotube Array−P3HT Based Heterojunction Solar Cells

Enhanced hydrogen sensing properties of graphene by introducing a mono-atom-vacancy

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Fabrication of hydrogen sensors with transparent titanium oxide nanotube-array thin films as sensing elements

Cited by 208 publications

References 26 publications

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Effects of structure of anodic TiO2 nanotube arrays on photocatalytic activity for the degradation of 2,3-dichlorophenol in aqueous solution

Visible to Near-Infrared Light Harvesting in TiO2 Nanotube Array−P3HT Based Heterojunction Solar Cells

Enhanced hydrogen sensing properties of graphene by introducing a mono-atom-vacancy

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Visible to Near-Infrared Light Harvesting in TiO₂ Nanotube Array−P3HT Based Heterojunction Solar Cells