Publications by authors named "Thierry Djenizian"

23 Publications

  • Page 1 of 1

Biomimetic models of the human eye, and their applications.

Nanotechnology 2021 May 3;32(30). Epub 2021 May 3.

Mines Saint-Etienne, Center of Microelectronics in Provence, Department of Flexible Electronics, F-13541 Gardanne, France.

Replicating the functionality of the human eye has been a challenge for more than a century, creating a great wealth of biomimetic and bioinspired devices, and providing ever improving models of the eye for myriad research purposes. As improvements in microelectronics have proceeded, individual components of the eye have been replicated, and models of the optical behaviour of the eye have improved. This review explores both work developed for improving medical components, with an ultimate aim of a fully functioning prosthetic eye, and work looking at improving existing devices through biomimetic means. It is hoped that this holistic approach to the subject will aid in the cross pollination of ideas between the two research foci. The review starts by summarising the reported measurements of optical parameters of various components of the eye. It then charts the development of individual bionic components. Particular focus is put on the development of bionic and biomimetic forms of the two main adaptive components of the eye, namely the lens and the iris, and the challenges faced in modelling the light sensitive retina. Work on each of these components is thoroughly reviewed, including an overview of the principles behind the many different approaches used to mimic the functionality, and discussion of the pros and cons of each approach. This is concluded by an overview of several reported models of the complete or semi-complete eye, including details of the components used and a summary of the models' functionality. Finally, some consideration is given to the direction of travel of this field of research, and which existing approaches are likely to bring us closer to the long term goal of a fully functional analogue of the eye.
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http://dx.doi.org/10.1088/1361-6528/abf3eeDOI Listing
May 2021

Changes in temperature inside an optomechanical model of the human eye during emulated transscleral cyclophotocoagulation.

Biomed Opt Express 2020 Aug 23;11(8):4548-4559. Epub 2020 Jul 23.

Mines Saint-Etienne, Center of Microelectronics in Provence, Department of Flexible Electronics, F-13541 Gardanne, France.

Currently, many diseases of the eye are treated by laser surgery. An understanding of light propagation and the heating of eye tissue during laser exposure is crucial to improving the outcome of these procedures. Here, we present the development of physical and computational models of the human eye by combining optical light propagation and thermal characteristics. For the physical model, all parts of the eye, including cornea, lens, ciliary body, sclera, aqueous and vitreous humors, and iris, were fabricated using a 3D printed holder and modified polydimethylsiloxane. We also present a computational model based on finite element analysis that allows for a direct comparison between the simulation and experimental measurements. These models provide an opportunity to directly assess the rise in temperature in all eye tissues. The simulated and physical models showed good agreement for the transmission of light at varying incident angles. The heating of optical components was investigated in the retina and the ciliary body during simulated laser surgery. Temperature increases of 45.3°C and 30.6°C in the retina and ciliary bodies, respectively, were found in the physical model after 1 minute of exposure to 186 mW of 850 nm laser radiation. This compared to 29.8°C and 33.9°C increases seen under the same conditions in the simulation model with human eye parameters and 48.1°C and 28.7°C for physical model parameters. These results and these models are very promising for further investigation of the impact of laser surgery.
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http://dx.doi.org/10.1364/BOE.385016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449722PMC
August 2020

TiO Nanotube Layers Decorated with AlO/MoS/AlO as Anode for Li-ion Microbatteries with Enhanced Cycling Stability.

Nanomaterials (Basel) 2020 May 17;10(5). Epub 2020 May 17.

Mines Saint-Etienne, Center of Microelectronics in Provence, Flexible Electronics Department, 13541 Gardanne, France.

TiO nanotube layers (TNTs) decorated with AlO/MoS/AlO are investigated as a negative electrode for 3D Li-ion microbatteries. Homogenous nanosheets decoration of MoS, sandwiched between AlO coatings within self-supporting TNTs was carried out using atomic layer deposition (ALD) process. The structure, morphology, and electrochemical performance of the AlO/MoS/AlO-decorated TNTs were studied using scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and chronopotentiometry. AlO/MoS/AlO-decorated TNTs deliver an areal capacity almost three times higher than that obtained for MoS-decorated TNTs and as-prepared TNTs after 100 cycles at 1C. Moreover, stable and high discharge capacity (414 µAh cm) has been obtained after 200 cycles even at very fast kinetics (3C).
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http://dx.doi.org/10.3390/nano10050953DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7279526PMC
May 2020

All-Solid-State Lithium Ion Batteries Using Self-Organized TiO Nanotubes Grown from Ti-6Al-4V Alloy.

Molecules 2020 May 1;25(9). Epub 2020 May 1.

Mines Saint-Etienne, Center of Microelectronics in Provence, Department of Flexible Electronics, F-13541 Gardanne, France.

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO as a cathode. The synthesis of self-organized TiO NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm μm (119 mAh g) at a kinetic rate of C/10.
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http://dx.doi.org/10.3390/molecules25092121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7248836PMC
May 2020

Editorial: Advances in Porous Semiconductor Research.

Front Chem 2020 6;8:122. Epub 2020 Mar 6.

Department of Materials Science and Engineering, Monash University, Clayton, VIC, Australia.

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http://dx.doi.org/10.3389/fchem.2020.00122DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7067815PMC
March 2020

Direct Pre-lithiation of Electropolymerized Carbon Nanotubes for Enhanced Cycling Performance of Flexible Li-Ion Micro-Batteries.

Polymers (Basel) 2020 Feb 11;12(2). Epub 2020 Feb 11.

Mines Saint-Etienne, Center of Microelectronics in Provence, Department of Flexible Electronics, F-13541 Gardanne, France.

Carbon nanotubes (CNT) are used as anodes for flexible Li-ion micro-batteries. However, one of the major challenges in the growth of flexible micro-batteries with CNT as the anode is their immense capacity loss and a very low initial coulombic efficiency. In this study, we report the use of a facile direct pre-lithiation to suppress high irreversible capacity of the CNT electrodes in the first cycles. Pre-lithiated polymer-coated CNT anodes displayed good rate capabilities, studied up to 30 C and delivered high capacities of 850 mAh g (313 μAh cm) at 1 C rate over 50 charge-discharge cycles.
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http://dx.doi.org/10.3390/polym12020406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7077669PMC
February 2020

Determination of optical parameters of the porcine eye and development of a simulated model.

J Biophotonics 2019 11 23;12(11):e201800398. Epub 2019 Jul 23.

Department of Flexible Electronics, Ecole Nationale Supérieure des Mines, Centre Microélectronique de Provence CMP-EMSE, Gardanne, France.

The eye is a very sophisticated system of optical elements for the preeminent sense of vision. In recent years, the number of laser surgery to correct the optical aberration such as myopia or astigmatism has significantly increased. Consequently, improving the knowledge related to the interactions of light with the eye is very important in order to enhance the efficiency of the surgery. For this reason, a complete optical characterization of the porcine eye is presented in this study. Kubelka-Munk and Inverse Adding-Doubling methods were applied to spectroscopy measurement to determine the absorption and scattering coefficients. Furthermore, the refractive index has been measured by ellipsometry. The different parameters were obtained for the cornea, lens, vitreous humor, sclera, iris, choroids and eyelid in the visible and infrared region. Thereafter, the results are implemented in a COMSOL Multiphysics® software to create an eye model. This model gives a better understanding of the propagation of light in the eye by adding optical parts such as the iris, the sclera or the ciliary bodies. Two simulations show the propagation of light from the cornea to the retina but also from the sclera to the retina. This last possibility provides a better understanding of light propagation during eye laser surgery such as, for example, transscleral cyclophotocoagulation. Figure: Eye simulation models allow the development of new laser treatments in a simple and safe way for patients. To this purpose, the creation of an eye simulated model based on optical parameters obtained from experimental data is presented in this study. This model will facilitate the understanding of the light propagation inside the porcine eye.
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http://dx.doi.org/10.1002/jbio.201800398DOI Listing
November 2019

Flexible Micro-Battery for Powering Smart Contact Lens.

Sensors (Basel) 2019 May 3;19(9). Epub 2019 May 3.

IMT Atlantique, Optics & Electronics Departments, CS 83818, F-29238 Brest CEDEX 3, France.

In this paper, we demonstrate the first attempt of encapsulating a flexible micro battery into a contact lens to implement an eye-tracker. The paper discusses how to scale the battery to power various circuits embedded in the contact lens, such as ASIC, photodiodes, etc., as well as how to combine the battery with external harvested energy sources. The fabricated ring battery has a surface area of 0.75 cm yielding an areal capacity of 43 µAh·cm at 20C. Based on simulated 0.35-µm CMOS ASIC power consumption, this value is large enough to allow powering the ASIC for 3 minutes. The functioning of the micro battery is demonstrated by powering an orange LED.
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http://dx.doi.org/10.3390/s19092062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6539253PMC
May 2019

Superior Electrochemical Performance of Thin-Film Thermoplastic Elastomer-Coated SnSb as an Anode for Li-ion Batteries.

Sci Rep 2019 Mar 13;9(1):4301. Epub 2019 Mar 13.

Mines Saint-Etienne, Center of Microelectronics in Provence, Department of Flexible Electronics, F - 13541, Gardanne, France.

The high failure strain of thermoplastic elastomers (TPEs) is a very desirable feature for rechargeable Li-ion batteries by improving the lifetime of high specific capacity anode materials that undergo mechanical fractures induced by large volume variations. In this work, poly(styrene-b-2-hydroxyethyl acrylate) called PS-b-PHEA was synthesized by a nitroxide meditated polymerization method. Owing to the use of a specific polystyrene macroinitiator (SG1), a suitable TPE copolymer with long hydroxyethyl acrylate blocks to ensure good mechanical properties is obtained for the first time. We show that the electrochemical properties of the PS-b-PHEA-coated SnSb anode are drastically improved by suppressing the crack formation at the surface of the electrode. Indeed, electrochemical characterization revealed that a high and stable gravimetric capacity over 100 cycles could be achieved. Moreover, excellent capacity reversibility was achieved when cycled at multiple C-rates and fast kinetics confirming the strong protection role of the polymer. The advanced chemical and mechanical properties of PS-b-PHEA open up promising perspectives to significantly improve the electrochemical performance of all electrodes that are known to suffer from large volume variations.
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http://dx.doi.org/10.1038/s41598-019-40835-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416307PMC
March 2019

Optical and Electrochemical Properties of Self-Organized TiO Nanotube Arrays From Anodized Ti-6Al-4V Alloy.

Front Chem 2019 8;7:66. Epub 2019 Feb 8.

Mines Saint-Etienne, Department of Flexible Electronics, Center of Microelectronics in Provence, Gardanne, France.

Due to their high specific surface area and advanced properties, TiO nanotubes (TiO NTs) have a great significance for production and storage of energy. In this paper, TiO NTs were synthesized from anodization of Ti-6Al-4V alloy at 60 V for 3 h in fluoride ethylene glycol electrolyte by varying the water content and further annealing treatment. The morphological, structural, optical and electrochemical performances of TiO NTs were investigated by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), UV-Visible spectroscopy and electrochemical characterization techniques. By varying the water content in the solution, a honeycomb and porous structure was obtained at low water content and the presence of (α + β) phase in Ti-6Al-4V alloy caused not uniform etching. With an additional increase in water content, a nanotubular structure is formed in the (α + β) phases with different morphological parameters. The anatase TiO NTs synthesized with 20 wt% HO shows an improvement in absorption band that extends into the visible region due the presence of vanadium oxide in the structure and the effective band gap energy () value of 2.25 eV. The TiO NTs electrode also shows a good cycling performance, delivering a reversible capacity of 82 mAh.g (34 μAh.cm.μm) at 1C rate over 50 cycles.
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http://dx.doi.org/10.3389/fchem.2019.00066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6375903PMC
February 2019

Electrodeposition of Polymer Electrolyte Into Porous LiNiMnO for High Performance All-Solid-State Microbatteries.

Front Chem 2018 23;6:675. Epub 2019 Jan 23.

Mines Saint-Etienne, Department of Flexible Electronics, Center of Microelectronics in Provence, Gardanne, France.

We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNiMnO) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage. These effects are attributed to the total filling of pores by the electrodeposited polymer that contributes to improve the reversible insertion of Li. A complete all-solid-state microbattery consisting of electropolymerized LNMO as the cathode, a thin polymer layer as the electrolyte, and TiO nanotubes as the anode has been successfully fabricated and tested.
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http://dx.doi.org/10.3389/fchem.2018.00675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6351485PMC
January 2019

ALD AlO-Coated TiO Nanotube Layers as Anodes for Lithium-Ion Batteries.

ACS Omega 2017 Jun 16;2(6):2749-2756. Epub 2017 Jun 16.

Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice, Czech Republic.

The utilization of the anodic TiO nanotube layers, with uniform AlO coatings of different thicknesses (prepared by atomic layer deposition, ALD), as the new electrode material for lithium-ion batteries (LIBs), is reported herein. Electrodes with very thin AlO coatings (∼1 nm) show a superior electrochemical performance for use in LIBs compared to that of the uncoated TiO nanotube layers. A more than 2 times higher areal capacity is received on these coated TiO nanotube layers (∼75 vs 200 μAh/cm) as well as higher rate capability and coulombic efficiency of the charging and discharging reactions. Reasons for this can be attributed to an increased mechanical stability of the TiO nanotube layers upon AlO coating, as well as to an enhanced diffusion of the Li ions within the coated nanotube layers. In contrast, thicker ALD AlO coatings result in a blocking of the electrode surface and therefore an areal capacity decrease.
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http://dx.doi.org/10.1021/acsomega.7b00463DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5494640PMC
June 2017

Bottom-Up Electrochemical Deposition of Poly(styrene sulfonate) on Nanoarchitectured Electrodes.

ACS Appl Mater Interfaces 2017 Jul 28;9(27):22902-22910. Epub 2017 Jun 28.

Aix Marseille Univ (AMU) , CNRS, Madirel (UMR 7246), Electrochemistry of Materials Group, site St Jérôme, 13397 Marseille, France.

The cathodic deposition of poly(styrene sulfonate) on nanoarchitectured TiO electrodes is explored by cyclic voltammetry and potentiostatic and galvanostatic experiments, showing a diffusion-controlled deposition described by Cottrell's law. The structure and composition of the polymer is evidenced by various spectroscopic techniques, including nuclear magnetic resonance, Fourier transform infrared, and X-ray photoelectron spectroscopy, and its morphology is studied by scanning electron microscopy. The average chain length can be estimated from the NMR spectra. The electropolymerization mechanism initiates by radical anion formation. The cycling behavior in half-cell batteries against Li metal is excellent, especially at high rates explored up to 10 C. The areal insertion capacity is above recent literature results, up to 80 μA h cm. The combination of normalized areal power density and areal energy density is one of the best reported in the literature.
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http://dx.doi.org/10.1021/acsami.7b04335DOI Listing
July 2017

Porous NASICON-Type Li3Fe2(PO4)3 Thin Film Deposited by RF Sputtering as Cathode Material for Li-Ion Microbatteries.

Nanoscale Res Lett 2016 Dec 17;11(1):365. Epub 2016 Aug 17.

Aix-Marseille University, CNRS, MADIRELLaboratory, UMR 7246, 13397, Marseille, France.

We report the electrochemical performance of porous NASICON-type Li3Fe2(PO4)3 thin films to be used as a cathode for Li-ion microbatteries. Crystalline porous NASICON-type Li3Fe2(PO4)3 layers were obtained by radio frequency sputtering with an annealing treatment. The thin films were characterized by XRD, SEM, and electrochemical techniques. The chronoamperometry experiments showed that a discharge capacity of 88 mAhg(-1) (23 μAhcm(-2)) is attained for the first cycle at C/10 to reach 65 mAhg(-1) (17 μAhcm(-2)) after 10 cycles with a good stability over 40 cycles.
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http://dx.doi.org/10.1186/s11671-016-1574-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988962PMC
December 2016

Anodized Ti3SiC2 As an Anode Material for Li-ion Microbatteries.

ACS Appl Mater Interfaces 2016 Jul 22;8(26):16670-6. Epub 2016 Jun 22.

Aix-Marseille University , CNRS, MADIREL Laboratory, UMR 7246, 13397 Marseille, France.

We report on the synthesis of an anode material for Li-ion batteries by anodization of a common MAX phase, Ti3SiC2, in an aqueous electrolyte containing hydrofluoric acid (HF). The anodization led to the formation of a porous film containing anatase, a small quantity of free carbon, and silica. By varying the anodization parameters, various oxide morphologies were produced. The highest areal capacity was achieved by anodization at 60 V in an aqueous electrolyte containing 0.1 v/v HF for 3 h at room temperature. After 140 cycles performed at multiple applied current densities, an areal capacity of 380 μAh·cm(-2) (200 μA·cm(-2)) has been obtained, making this new material, free of additives and binders, a promising candidate as a negative electrode for Li-ion microbatteries.
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http://dx.doi.org/10.1021/acsami.6b03528DOI Listing
July 2016

Porous Silicon Nanotube Arrays as Anode Material for Li-Ion Batteries.

ACS Appl Mater Interfaces 2015 Sep 14;7(37):20495-8. Epub 2015 Sep 14.

Aix-Marseille University , CNRS, MADIREL Laboratory, UMR 7246, 13397 Marseille, France.

We report the electrochemical performance of Si nanotube vertical arrays possessing thin porous sidewalls for Li-ion batteries. Porous Si nanotubes were fabricated on stainless steel substrates using a sacrificial ZnO nanowire template method. These porous Si nanotubes are stable at multiple C-rates. A second discharge capacity of 3095 mAh g(-1) with a Coulombic efficiency of 63% is attained at a rate of C/20 and a stable gravimetric capacity of 1670 mAh g(-1) obtained after 30 cycles. The high capacity values are attributed to the large surface area offered by the porosity of the 3D nanostructures, thereby promoting lithium-ion storage according to a pseudocapacitive mechanism.
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http://dx.doi.org/10.1021/acsami.5b05705DOI Listing
September 2015

Synthesis of carbon/sulfur nanolaminates by electrochemical extraction of titanium from Ti₂SC.

Angew Chem Int Ed Engl 2015 Apr 25;54(16):4810-4. Epub 2015 Feb 25.

A. J. Drexel Nanomaterials Institute, and Materials Science and Engineering Department, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (USA).

Herein we electrochemically and selectively extract Ti from the MAX phase Ti2SC to form carbon/sulfur (C/S) nanolaminates at room temperature. The products are composed of multi-layers of C/S flakes, with predominantly amorphous and some graphene-like structures. Covalent bonding between C and S is observed in the nanolaminates, which render the latter promising candidates as electrode materials for Li-S batteries. We also show that it is possible to extract Ti from other MAX phases, such as Ti3AlC2, Ti3SnC2, and Ti2GeC, suggesting that electrochemical etching can be a powerful method to selectively extract the "M" elements from the MAX phases, to produce "AX" layered structures, that cannot be made otherwise. The latter hold promise for a variety of applications, such as energy storage, catalysis, etc.
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http://dx.doi.org/10.1002/anie.201500110DOI Listing
April 2015

Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte.

Nanoscale Res Lett 2014 2;9(1):544. Epub 2014 Oct 2.

Aix-Marseille Université, CNRS, LP3 UMR 7341, F-13288, Marseille Cedex 9, France ; Aix-Marseille Université, CNRS, MADIREL UMR 7246, F-13397, Marseille Cedex 20, France.

This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance ((1)H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte.
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http://dx.doi.org/10.1186/1556-276X-9-544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4194452PMC
October 2014

Three-dimensional self-supported metal oxides for advanced energy storage.

Adv Mater 2014 Jun 2;26(21):3368-97. Epub 2014 Apr 2.

Aix-Marseille University, CNRS, LP3 Laboratory, UMR 7341, 13288, Marseille, France.

The miniaturization of power sources aimed at integration into micro- and nano-electronic devices is a big challenge. To ensure the future development of fully autonomous on-board systems, electrodes based on self-supported 3D nanostructured metal oxides have become increasingly important, and their impact is particularly significant when considering the miniaturization of energy storage systems. This review describes recent advances in the development of self-supported 3D nanostructured metal oxides as electrodes for innovative power sources, particularly Li-ion batteries and electrochemical supercapacitors. Current strategies for the design and morphology control of self-supported electrodes fabricated using template, lithography, anodization and self-organized solution techniques are outlined along with different efforts to improve the storage capacity, rate capability, and cyclability.
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http://dx.doi.org/10.1002/adma.201306126DOI Listing
June 2014

Sulfidated TiO2 nanotubes: a potential 3D cathode material for Li-ion micro batteries.

Chem Commun (Camb) 2013 May 20;49(39):4205-7. Epub 2012 Nov 20.

Aix Marseille University, CNRS, LP3 UMR 7341, 13288, Marseille, France.

In this work, self-organized titania nanotubes are sulfidated by an annealing treatment to produce TiOxSy nanotubes. Morphological, structural and electrochemical analyses show that this 3D nanostructured electrode is a potential cathode material for Li-ion microbatteries.
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http://dx.doi.org/10.1039/c2cc36857aDOI Listing
May 2013

Electrochemical fabrication and properties of highly ordered Fe-doped TiO2 nanotubes.

Chemphyschem 2012 Nov 28;13(16):3707-13. Epub 2012 Aug 28.

Aix Marseille University, CNRS, LP UMR, Marseille, France.

Highly-ordered Fe-doped TiO(2) nanotubes (TiO(2)nts) were fabricated by anodization of co-sputtered Ti-Fe thin films in a glycerol electrolyte containing NH(4)F. The as-sputtered Ti-Fe thin films correspond to a solid solution of Ti and Fe according to X-ray diffraction. The Fe-doped TiO(2)nts were studied in terms of composition, morphology and structure. The characterization included scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Mott-Schottky analysis. As a result of the Fe doping, an indirect bandgap of 3.0 eV was estimated using Tauc's plot, and this substantial red-shift extends its photoresponse to visible light. From the Mott-Schottky analysis, the flat-band potential (E(fb)) and the charge carrier concentration (N(D)) were determined to be -0.95 V vs Ag/AgCl and 5.0×10(19) cm(-3) respectively for the Fe-doped TiO(2)nts, whilst for the undoped TiO(2)nts, E(fb) of -0.85 V vs Ag/AgCl and N(D) of 6.5×10(19) cm(-3) were obtained.
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http://dx.doi.org/10.1002/cphc.201200406DOI Listing
November 2012

Highly conformal electrodeposition of copolymer electrolytes into titania nanotubes for 3D Li-ion batteries.

Nanoscale Res Lett 2012 Jun 27;7(1):349. Epub 2012 Jun 27.

Aix Marseille Université, CNRS, Chemistry of Materials Research Group LP3 UMR 7341, Marseille, F-13288, France.

The highly conformal electrodeposition of a copolymer electrolyte (PMMA-PEO) into self-organized titania nanotubes (TiO2nt) is reported. The morphological analysis carried out by scanning electron microscopy and transmission electron microscopy evidenced the formation of a 3D nanostructure consisting of a copolymer-embedded TiO2nt. The thickness of the copolymer layer can be accurately controlled by monitoring the electropolymerization parameters. X-ray photoelectron spectroscopy measurements confirmed that bis(trifluoromethanesulfone)imide salt was successfully incorporated into the copolymer electrolyte during the deposition process. These results are crucial to fabricate a 3D Li-ion power source at the micrometer scale using TiO2nt as the negative electrode.
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http://dx.doi.org/10.1186/1556-276X-7-349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3536562PMC
June 2012

Electrochemical fabrication of Sn nanowires on titania nanotube guide layers.

Nanotechnology 2008 May 14;19(20):205601. Epub 2008 Apr 14.

University of Aix-Marseille I, II, III-CNRS, UMR 6264: Laboratoire Chimie Provence, Electrochemistry of Materials Research Group, Centre Saint Jérôme, F-13397 Marseille Cedex 20, France.

We describe a novel approach for the fabrication of tailored nanowires using a two-step electrochemical process. It is demonstrated that self-organized TiO(2) nanotubes can be used to activate and guide the electrochemical growth of Sn crystallites, leading to the formation of vertical features with a high aspect ratio. We show that the dimensions and the density of Sn crystallites depend on the electrodeposition parameters.
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http://dx.doi.org/10.1088/0957-4484/19/20/205601DOI Listing
May 2008
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