Effect of Annealing Temperature on the Hydrogen Production of TiO<sub>2</sub> Nanotube Arrays in a Two-Compartment Photoelectrochemical Cell

Sun, Yan; Yan, Kangping; Wang, Guixin; Guo, Wei; Ma, Tingli

doi:10.1021/jp1116118

Cited by 84 publications

(55 citation statements)

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“…As described later, this deactivation was accompanied by the transition of anatase into rutile crystallites and the partial degradation of the NT structure in a similar way to previous reports. [3][4][5][6] Next, we focused on the effect of annealing treatments in a reductive atmosphere under a N 2 stream. Figures 1b and 2b show the results of PEC performances of TiO 2 NT electrodes annealed in a N 2 stream.…”

Section: Pec Performances Of Tiomentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10] Importantly, TiO 2 can be a platform for developing visible-light-responsive photoelectrodes for water splitting under sunlight because it is easily sensitized by dye molecules, quantum dots, and narrow bandgap semiconductors. 2,11 Impurity doping also can provide visible light absorption to TiO 2 by forming an impurity level and a sub-band in the bandgap.…”

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confidence: 99%

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Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Amano

Mukohara

Shintani

2018

J. Electrochem. Soc.

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TiO 2 nanotube arrays fabricated by anodization and post annealing are extensively studied as an n-type semiconductor electrode for photoelectrochemical (PEC) water splitting owing to their large surface area and efficient electron transport property. The rutile phase is believed to be an inactive component of the TiO 2 nanotube's electrode because annealing at high temperatures decreases the PEC efficiency with the transformation of anatase into rutile crystallites. In contrast, herein, we found that photoelectrodes prepared by two-step annealing, in which TiO 2 nanotubes annealed in air at 650 • C were then treated in a nitrogen atmosphere at a higher temperature, exhibited higher PEC efficiency despite the anatase nanotube structure changes to rutile particles. Sheet resistance measurement and Mott-Schottky analysis showed that the enhanced efficiency is attributed to a significant increase in donor density by partial reduction of rutile TiO 2 . The second annealing in the reductive atmosphere is essential to provide a columnar arrangement of TiO 2 crystallites with high donor density resulting in high PEC properties for the oxidation of water to O 2 . This suggests that improving the electron transport property by the enhanced electrical conductivity and the interconnected nanocrystalline structure is important to enhance the PEC property of rutile TiO 2 particulate photoanodes. Photoelectrochemical (PEC) water splitting is a promising technology for producing H 2 using solar energy. A key component necessary to achieve a PEC system is the development of highly efficient photoelectrodes. Since the discovery of PEC water oxidation on TiO 2 electrodes, n-type oxide electrodes have been extensively studied as photoanodes for four-electron oxidation of water to evolve O 2 .1 Among them, highly ordered vertically oriented TiO 2 nanotube (NT) electrodes have attracted much research attention owing to their high efficiency in the PEC reaction after crystallization to anatase by annealing.2-10 Importantly, TiO 2 can be a platform for developing visible-light-responsive photoelectrodes for water splitting under sunlight because it is easily sensitized by dye molecules, quantum dots, and narrow bandgap semiconductors.2,11 Impurity doping also can provide visible light absorption to TiO 2 by forming an impurity level and a sub-band in the bandgap. 12,13The nanotubular crystalline structure exhibits a large surface area, which increases the interface of a semiconductor/liquid and decreases the traveling length of photogenerated holes, which results in improved charge separation.2 The large pore volume inside the hollow structure provides fast diffusion of electrolytes and evolved O 2 gas. Furthermore, the one-dimensional interconnected nanocrystalline structure provides excellent electron transport pathways for the photoexcited electrons to the back contact substrate.2 The fast electron transport, which means long diffusion lengths of photoexcited electrons, enables the optical path length, i.e. the NT length, to increa...

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Section: Pec Performances Of Tiomentioning

confidence: 99%

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confidence: 99%

Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Amano

Mukohara

Shintani

2018

J. Electrochem. Soc.

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“…The linear sweep voltammetry and photocurrent density are recorded. The efficiency of photoconversion is calculated as follows [54].…”

Section: Photoelectrochemical Performancementioning

confidence: 99%

Fast and Large-Scale Anodizing Synthesis of Pine-Cone TiO2 for Solar-Driven Photocatalysis

et al. 2017

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Anodization has been widely used to synthesize nanostructured TiO 2 films with promising photocatalytic performance for solar hydrogen production and pollution removal. However, it usually takes a few hours to obtain the right nanostructures even on a small scale (e.g., 10 mm × 20 mm). In order to attract interest for industrial applications, fast and large-scale fabrication is highly desirable. Herein, we demonstrate a fast and large-scale (e.g., 300 mm × 360 mm) synthesis of pine-cone TiO 2 nanostructures within two min. The formation mechanism of pine-cone TiO 2 is proposed. The pine-cone TiO 2 possesses a strong solar absorption, and exhibits high photocatalytic activities in photo-oxidizing organic pollutants in wastewater and producing hydrogen from water under natural sunlight. Thus, this study demonstrates a promising method for fabricating TiO 2 films towards practical photocatalytic applications.

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“…Therefore, the discussion of optimal annealing temperature and crystallinity is difficult. The highest photodegradation efficiency has been reported using NT films annealed at different temperatures such as 450°C [15], 500°C [16], 550°C [17], and 600°C [18]. These earlier studies have concluded that the tubular structure was stable at or below the optimal temperatures.…”

Section: Introductionmentioning

confidence: 99%

Anatase TiO2 nanotube powder film with high crystallinity for enhanced photocatalytic performance

Lin¹,

Liu²,

Zhu³

et al. 2016

Nano Online

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Cite as: Jia Lin, Xiaolin Liu, Shu Zhu, Yongsheng Liu. Anatase TiO2 nanotube powder film with high crystallinity for enhanced photocatalytic performance , nano Online We report on the synthesis of TiO2 nanotube (NT) powders using anodic oxidation and ultrasonication. Compared to free-standing NT array films, the powder-type NTs can be easily fabricated in a cost-effective way. Particularly, without the substrate effect arising from underlying Ti metals, highly crystallized NT powders with intact tube structures and pure anatase phase can be obtained using high-temperature heat treatment. The application of NTs with different crystallinity for the photocatalytic decomposition of methylene blue (MB) was then demonstrated. The results showed that with increasing annealing temperature, the photocatalytic decomposition rate was gradually enhanced, and the NT powder electrode annealed at 650°C showed the highest photoactivity. Compared to typical NTs annealed at 450°C, the rate constant increased by 2.7-fold, although the surface area was 21% lower. These findings indicate that the better photocatalytic activity was due to the significantly improved crystallinity of anatase anodic NTs in powder form, resulting in a low density of crystalline defects. This simple and efficient approach is applicable for scaled-up water purification and other light utilization applications.

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Effect of Annealing Temperature on the Hydrogen Production of TiO₂ Nanotube Arrays in a Two-Compartment Photoelectrochemical Cell

Cited by 84 publications

References 40 publications

Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Fast and Large-Scale Anodizing Synthesis of Pine-Cone TiO2 for Solar-Driven Photocatalysis

Anatase TiO2 nanotube powder film with high crystallinity for enhanced photocatalytic performance

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Effect of Annealing Temperature on the Hydrogen Production of TiO2 Nanotube Arrays in a Two-Compartment Photoelectrochemical Cell

Cited by 84 publications

References 40 publications

Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Rutile Titania Particulate Photoelectrodes Fabricated by Two-Step Annealing of Titania Nanotube Arrays

Fast and Large-Scale Anodizing Synthesis of Pine-Cone TiO2 for Solar-Driven Photocatalysis

Anatase TiO2 nanotube powder film with high crystallinity for enhanced photocatalytic performance

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Effect of Annealing Temperature on the Hydrogen Production of TiO₂ Nanotube Arrays in a Two-Compartment Photoelectrochemical Cell