A review on highly ordered, vertically oriented TiO2 nanotube arrays: Fabrication, material properties, and solar energy applications

The worldwide thirst for portable consumer electronics in the 1990s had an enormous impact on portable power. Lithium ion batteries, in which lithium ions shuttle between an insertion cathode (e.g., LiCoO2) and an insertion anode (e.g., carbon), emerged as the power source of choice for the highperformance rechargeable-battery market. The performance advantages were so significant that lithium ion batteries not only replaced Ni-Cd batteries but left the purported successor technology, nickel-metal hydride, in its wake.1 The thick metal plates of * To whom correspondence should be addressed. J.W.L: e-mail, jwlong@ccs.nrl.navy.mil; telephone, (+1)202-404-8697. B.D.: e-mail, bdunn@ucla.edu; telephone, (+1)310-825-1519. D.R.R.: e-mail, rolison@nrl.navy.mil; telephone, (+1)202-767-3617. H.S.W.: e-mail, white@chem.utah.edu; telephone, (+1)810-585-6256. † Naval Research Laboratory. ‡ UCLA. § University of Utah. 4463 Chem. Rev. 2004, 104, 4463−4492

Three-dimensional battery architectures.

In this study highly ordered titania nanotube arrays of variable wall thickness are used to photocleave water under ultraviolet irradiation. We demonstrate that the wall thickness and length of the nanotubes can be controlled via anodization bath temperature. We find that the nanotube wall thickness is a key parameter influencing the magnitude of the photoanodic response and the overall efficiency of the water-splitting reaction. For 22 nm inner pore diameter nanotube arrays, those fabricated in a 5 °C anodization bath, 224 nm length and 34 nm wall thickness produced a photoanodic response that was thrice that of a nanotube array fabricated in a 50 °C anodization bath, 120 nm length and 9 nm wall-thickness. At high anodic polarization, above 1 V, the quantum efficiency under 337 nm illumination was greater than 90%. For the 5 °C anodization bath samples (22 nm pore-diameter, 34 nm wall thickness), upon 320−400 nm illumination at an intensity of 100 mW/cm2, hydrogen gas was generated at the power−time norm...

Enhanced Photocleavage of Water Using Titania Nanotube Arrays

Described is the fabrication of self-aligned highly ordered TiO2 nanotube arrays by potentiostatic anodization of Ti foil having lengths up to 134 μm, representing well over an order of magnitude i...

Anodic Growth of Highly Ordered TiO2 Nanotube Arrays to 134 μm in Length

and Perspectives Sophie Carenco,†,‡,§,∥,⊥ David Portehault,*,†,‡,§ Ced́ric Boissier̀e,†,‡,§ Nicolas Meźailles, and Cleḿent Sanchez*,†,‡,§ †Chimie de la Matier̀e Condenseé de Paris, UPMC Univ Paris 06, UMR 7574, Colleg̀e de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France ‡Chimie de la Matier̀e Condenseé de Paris, CNRS, UMR 77574, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Chimie de la Matier̀e Condenseé de Paris, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France

Nanoscaled metal borides and phosphides: recent developments and perspectives

All manifestations of pores in silicon are reviewed and discussed with respect to possible applications. Particular emphasis is put on macropores, which are classified in detail and reviewed in the context of pore formation models. Applications of macro-, meso-, and micropores are discussed separately together with some consideration of specific experimental topics. A brief discussion of a stochastic model of Si electrochemistry that was found useful in guiding experimental design for specific pore formation concludes the paper.

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Formation and application of porous silicon

The paper reviews electrochemically etched pores in III-V compound semiconductors (GaP, InP, GaAs) with emphasis on nucleation and formation mechanisms, pore geometries and morphologies, and to several instances of self-organization. Self-organization issues include the formation of single-crystalline two-dimensional hexagonal arrays of pores with lattice constants as small as 100 nm found in InP, synchronized and unsynchronized diameter oscillations coupled to current and voltage oscillations, and pore domain formation. The findings are discussed in relation to pores observed in silicon. Some novel porperties of the porous layers obtained in III-V compounds are briefly described.

Pores in III–V Semiconductors

A model is presented with the potential to account for all processes of the reactive Si–liquid interface including, e.g. current oscillations, and the formation of nano-, meso, and macropores with their specific dependence on crystal orientation. The model assumes that current flow is spatially and temporally inhomogeneous-current thus flows in current ‘lines’ occurring in current ‘bursts’. The mean cycle time between correlated current bursts is mostly given by the kinetics of oxide dissolution and hydrogen passivation (which introduces a strong surface orientation dependence). Structure generation at the Si electrode (current oscillations in the time domain or pore formation in the space domain) under these assumptions is a self-organized process resulting from an interplay of synchronizing and desynchronizing mechanisms. Synchronizing mechanisms always couple the nucleation of a new current burst in a specific area to the history of that area, desynchronizing mechanisms may also depend on the interaction of current burst. Examples for synchronizing mechanisms are enhanced nucleation probabilities on (100) surfaces, response to local oxides from another current burst, or coupling of current bursts by space charge region effects. Desynchronization results, e.g. from quantum wire effects, or local reduction of reactants or potential by a current line. The model accounts qualitatively for most if not all observed phenomena, gives a number of quantitative relations, and makes numerous predictions.

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Pore formation mechanisms for the Si-HF system

https://www.tf.uni-kiel.de/matwis/amat/publications/solar_energy_materials_cello/cello_solar_energy_materials_and_solar_cells.pdf

CELLO: an advanced LBIC measurement technique for solar cell local characterization

Self-organized single crystalline two-dimensional hexagonal arrays of pores in InP semiconductor compound are reported. We show that the self-arrangement of pores can be obtained on n-type substrates with (100) and (111) orientations. The long-range order in pore distribution evidenced in (100)InP samples proves to be favored by the so-called nucleation layer exhibiting branching pores oriented along 〈111〉 directions. The combination of long-range order with self-induced diameter oscillations is shown to be promising for nonlithographic growth of three-dimensional pore crystals.

J. Carstensen

Papers

Formation and application of porous silicon

Pores in III–V Semiconductors

Pore formation mechanisms for the Si-HF system

CELLO: an advanced LBIC measurement technique for solar cell local characterization

Self-organized growth of single crystals of nanopores