Search query: tio2 thin film

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abstract: Electrolyte layer, made up of an ionic conductor with ignorable electronic conductivity, plays vital roles in transporting ions as well as blocking electron passage in electrochemical devices like a solid oxide fuel cell (SOFC) The electronic conductivity of the electrolyte has been always blamed for bringing in the short circuiting problem. In this study, however, we demonstrate that the dominant issue is not the electronic conductivity of electrolytes but the energy band diagram of the device. Using a semiconductor TiO2 thin film as an electrolyte, we present a novel design of fuel cell devices from the perspective of the energy band structure and alignment. A TiO2 thin film was fabricated by a mass productive spin coating method. An OCV of 1.1 V and maximum power output of 364 mW cm 2 at 550 degC were achieved, which proves that TiO2 plays the role of an electrolyte with sufficient ionic transportation while no electronic short circuiting problem occurs. The online intercalation of Li into TiO2 enables the creation of more oxygen vacancies. Additionally, proton incorporation and conducting mechanisms in TiO2 have been verified and discussed. This work provides a new method for suppressing the electronic conductivity of electrolytes as well as developing functional electrolytes from a well known semiconductor for advanced low temperature SOFCs.
author_names: Wenjing Dong

Yuzhu Tong

Bin Zhu

Haibo Xiao

Lili Wei

Chaoyu Huang

Baoyuan Wang

Xunying Wang

Jung-Sik Kim

Haixia Wang
title: Semiconductor TiO2 thin film as an electrolyte for fuel cells
year: 2019

abstract: This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+ Ti4+ O2 oxygen vacancies, OH group and optical properties was studied using X ray photon spectroscopy (XPS) and UV Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 seconds. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was observed in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.
author_names: Bandna Bharti

Santosh Kumar

Heung-no Lee

Rajesh Kumar
title: Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatment
venue: Scientific reports
year: 2016

abstract: Graphene oxide platelets synthesized by using a chemical exfoliation method were deposited on anatase TiO2 thin films. Postannealing of the graphene oxide/TiO2 thin films at 400 degC in air resulted in partial formation of a Ti C bond between the platelets and their beneath thin film. By using atomic force microscopy and X ray photoelectron spectroscopy analyses, UV visible light induced photocatalytic reduction of the graphene oxide platelets of the annealed graphene oxide/TiO2 thin films immersed in ethanol was studied for the different irradiation times. After 4 h of photocatalytic reduction, the vertical space between the platelets decreased from about 1.1 to less than 0.8 nm and the concentration of the C O bond was reduced 85% indicating effective reduction of the graphene oxide platelets to the graphene ones. The graphene oxide/TiO2 thin films reduced at different irradiation times were utilized as nanocomposite photocatalysts for degradation of E. coli bacteria in an aqueous solution under solar li.
author_names: Omid Akhavan

Elham Ghaderi
title: Photocatalytic Reduction of Graphene Oxide Nanosheets on TiO2 Thin Film for Photoinactivation of Bacteria in Solar Light Irradiation
year: 2009

abstract: In the present study, a selectively exposed (101) crystal facet engineered TiO2 photoanode is investigated for the higher efficiency of the hydrogen evolution reaction. To date, even though the photoelectrochemical performance (PEC) dependent on exposed crystal facets has been calculated and demonstrated in semiconducting microcrystals, selectively exposed crystal facets of photocatalyst thin films have not been reported yet. Herein, we demonstrate a TiO2 thin film photoanode with 100% exclusively exposed crystal facets and suggest a methodology to obtain metal oxide thin film photoanodes with selectively exposed crystal facets. A selectively exposed crystal facet manipulated metal oxide thin film photoanode is fabricated over pre synthesized microcrystals through a three step strategy: (1) hydrothermal synthesis of microcrystals, (2) positioning of microcrystals via polymer induced manual assembly, and (3) fabrication of selectively exposed crystal facets of a TiO2 thin film through a secondary growth hydrothermal reaction. Based on the synthesis of representative TiO2 microcrystals with dominantly exposed (101) (100) and (001) crystal facets, the selectively exposed crystal faceted TiO2 thin film photoanode is comparatively investigated for practical PEC performance. The photocurrent density of the selectively exposed (101) crystal faceted TiO2 thin film photoanode is determined as 0.13 mA cm 2 and has an 18% conversion efficiency of incident photon to current at a 0.65 V Ag/AgCl potential under AM 1.5G illumination. Its photoelectrochemical hydrogen production reached 0.07 mmol cm 2 for 12 h, which is higher than those of (100) and (001) faceted photoelectrodes.
author_names: Chang Woo Kim

So-Jin Yeob

Hui-Ming Cheng

Young Soo Kang
title: A selectively exposed crystal facet engineered TiO2 thin film photoanode for the higher performance of the photoelectrochemical water splitting reaction
year: 2015

abstract: TiO2 thin film based, chemiresistive sensors for NO2 gas which operate at room temperature under ultraviolet (UV) illumination have been demonstrated in this work. The rf sputter deposited and post annealed TiO2 thin films have been characterized by atomic force microscopy, X ray photoelectron spectroscopy, and X ray diffraction to obtain surface morphology, chemical state, and crystal structure, respectively. UV vis absorption spectroscopy and Tauc plots show the optical properties of the TiO2 films. Under UV illumination, the NO2 sensing performance of the TiO2 films shows a reversible change in resistance at room temperature. The observed change in electrical resistivity can be explained by the modulation of surface adsorbed oxygen. This work is the first demonstration of a facile TiO2 sensor for NO2 analyte that operates at room temperature under UV illumination.
author_names: Ting Xie

Nichole F Sullivan

Kristen Lisa Steffens

Baomei Wen

Guannan Liu

Ratan K Debnath

Albert V Davydov

Romel D Gomez

Abhishek Motayed
title: UV assisted room temperature chemiresistive NO2 sensor based on TiO2 thin film.
venue: Journal of alloys and compounds
year: 2015

abstract: To examine the special features of the antibacterial effect for a thin transparent titanium dioxide (TiO2) film, the photocatalytic degradation of endotoxin, which is a pyrogenic constituent of Escherichia coli (E. coli) as well as its bactericidal activity, was investigated. The TiO2 films were prepared from titanium isopropoxide solution, annealing at 500 degC. The bactericidal activity for E. coli cells was estimated by survival ratio calculated from the number of viable cells which form colonies on the nutrient agar plates. The endotoxin concentration was determined by the Limulus tests. When E. coli cells were killed by the TiO2 photocatalyst under UV irradiation, the endotoxin from the cells was also degraded efficiently. This result shows that the TiO2 photocatalyst has both bactericidal activity and decomposing activity for the endotoxin (i.e. detoxifying activity) The bactericidal effect of the TiO2 thin film results from both inactivating the viability of the bacteria and the destruction of the.
author_names: Kayano Sunada

Yoshihiko Kikuchi

+ and Kazuhito Hashimoto

Akira Fujishima
title: Bactericidal and Detoxification Effects of TiO2 Thin Film Photocatalysts
year: 1998

abstract: We develop a simple approach to fabricate graphene loaded TiO(2) thin films on glass substrates by the spin coating technique. Our graphene loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene loaded TiO(2) thin film also contributes to the self cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd) and further shows its capability for the application of self cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene loaded TiO(2) films may have the potential use in various indoor applications.
author_names: Srinivasan Anandan

Tata Narasinga Rao

Marappan Sathish

Dinesh Rangappa

Itaru Honma

Masahiro Miyauchi
title: Superhydrophilic graphene loaded TiO2 thin film for self cleaning applications.
venue: ACS applied materials interfaces
year: 2013

abstract: Flat anatase TiO2 thin film deposited at room temperature shows the natural hydrophobicity, which is destroyed by 400 degC vacuum annealing. On the basis of the analysis of surface composition and structure, the origin of hydrophobicity of the flat TiO2 film can be identified as (1) approximately fully stoichiometric TiO2 and (2) hydrocarbon adsorbates on the film surface. We further validate that interfacial water molecules near the surface of the as prepared TiO2 film are oriented in the hydrophobic hydration structure via Fourier transform infrared/attenuated total reflection. Moreover, the as prepared TiO2 film also shows a smart surface reversibly switched between hydrophobicity and super hydrophilicity. During the recovery process of hydrophobicity, the irradiated films show the wettability with water contact angle of 107 1.7, 72 2.5, 80 1.1, and 17 1.3deg corresponding to after a week of exposure to ambient air, O2, CF4, and Ar, respectively. It can be strongly reinforced that the stoichiometry and the adsorbates both play an important role in forming the hydrophobic TiO2 films.
author_names: Jianzha Zheng

Shanhu Bao

Yu Guo

Ping Jin
title: Natural hydrophobicity and reversible wettability conversion of flat anatase TiO2 thin film.
venue: ACS applied materials interfaces
year: 2014

abstract: Titanium dioxide (TiO2) has been widely used in the photodegradation of organic contaminants and wastewater treatment in recent years. However, the mechanism of photocatalytic reaction on TiO2 surfaces is still poorly understood, especially for the reactions under real environmental conditions. In the present study, the sum frequency generation vibrational spectroscopy, a surface specific tool, has been employed to in situ study the dissociation and photooxidation reaction of CH3OH on TiO2 thin film, which served as a model system of photooxidizing organic compounds. The experimental results show that mixing O2 with CH3OH promotes more CH3OH dissociation to produce CH3O, and UV light can not only induce CH3OH dissociation to CH3O but also generate large nonresonance. To mimic the photodegradation process of organics, removing methoxy on the TiO2 thin film has been investigated under both aerobic and anaerobic conditions. We have observed two types of methoxy, photocatalytically reactive under both conditi.
author_names: Ran-ran Feng

Anan Liu

Shuo Liu

Jiao-jian Shi

Ruidan Zhang

Zefeng Ren
title: In Situ Studies on the Dissociation and Photocatalytic Reactions of CH3OH on TiO2 Thin Film by Sum Frequency Generation Vibrational Spectroscopy
year: 2015

abstract: Abstract Single phase rutile type TiO2 thin films with a high refractive index (n) and a low extinction coefficient (k) prepared on glass are expected to improve the performance of anti reflection coatings. In this study, TiO2 thin films were prepared by the pulsed laser deposition (PLD) method at temperatures ranging from room temperature to 600 degC under an oxygen partial pressure of 1 9 Pa or a 10 5 Pa vacuum, and their crystal structure, microstructure and optical properties were investigated. A single phase rutile type TiO2 thin film was successfully prepared on a glass substrate by depositing at room temperature in a vacuum followed by post annealing at 450 degC in air. A nanocrystalline oxygen deficient phase in the as deposited films plays an important role in the formation of the single rutile phase during post annealing. The single phase rutile type TiO2 thin films showed excellent optical properties, with n 3.14 and k
author_names: Akihiro Ishii

Yoko Nakamura

Itaru Oikawa

Atsunori Kamegawa

Hitoshi Takamura
title: Low temperature preparation of high n TiO2 thin film on glass by pulsed laser deposition
year: 2015