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Florian Le Formal

Cette personne n’est plus à l’EPFL

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Publications associées (39)

Rate Law Analysis of Water Oxidation on a Hematite Surface

Michael Graetzel, Florian Le Formal, Stanley David Tilley

Water oxidation is a key chemical reaction, central to both biological photosynthesis and artificial solar fuel synthesis strategies. Despite recent progress on the structure of the natural catalytic site, and on inorganic catalyst function, determining th ...

American Chemical Society2015

Challenges towards Economic Fuel Generation from Renewable Ellectricity: The Heed for Efficient Electro-Catalysis

Kevin Sivula, Florian Le Formal, Wiktor Stefan Bourée, Mathieu Steven Prévot

Utilizing renewable sources of energy is very attractive to provide the growing population on earth in the future but demands the development of efficient storage to mitigate their intermittent nature. Chemical storage, with energy stored in the bonds of c ...

Swiss Chemical Soc2015

Ultrafast Charge Carrier Recombination and Trapping in Hematite Photoanodes under Applied Bias

Michael Graetzel, Maurin Cornuz, Florian Le Formal, Stanley David Tilley, Xiaoyan Wang

Transient absorption spectroscopy on subpicosecond to second time scales is used to investigate photogenerated charge carrier recombination in Si-doped nanostructured hematite (alpha-Fe2O3) photoanodes as a function of applied bias. For unbiased hematite, ...

American Chemical Society2014

Hematite photoelectrodes for water splitting: evaluation of the role of film thickness by impedance spectroscopy

Michael Graetzel, Kevin Sivula, Florian Le Formal

The electrochemical behavior of alpha-Fe2O3 photoelectrodes prepared by spray pyrolysis with different thicknesses was examined under dark and illumination conditions. The main charge transport phenomena occurring in the PEC cell photoelectrodes were chara ...

Royal Soc Chemistry2014

Back Electron-Hole Recombination in Hematite Photoanodes for Water Splitting

Michael Graetzel, Maurin Cornuz, Florian Le Formal, Stanley David Tilley

The kinetic competition between electron-hole recombination and water oxidation is a key consideration for the development of efficient photoanodes for solar driven water splitting. In this study, we employed three complementary techniques, transient absor ...

American Chemical Society2014

Solid-State Dye-Sensitized Solar Cells using Ordered TiO2 Nanorods on Transparent Conductive Oxide as Photoanodes

Michael Graetzel, Shaik Mohammed Zakeeruddin, Carole Graetzel, Robin Humphry-Baker, Soo-Jin Moon, Mingkui Wang, Florian Le Formal

TiO2 nanorod arrays were prepared on top of a transparent conductive glass substrate covered with a thin TiO2 compact layer. Solid-state dye-sensitized solar cells (SSDSCs) were fabricated using these structured TiO2 films sensitized with C106 dye as a pho ...

American Chemical Society2012

The Transient Photocurrent and Photovoltage Behavior of a Hematite Photoanode under Working Conditions and the Influence of Surface Treatments

Michael Graetzel, Kevin Sivula, Florian Le Formal

Hematite (alpha-Fe2O3) is widely recognized as a promising candidate for the production of solar fuels via water splitting, but its intrinsic optoelectronic properties have limited its performance to date. In particular, the large electrochemical overpoten ...

American Chemical Society2012

A Ga2O3 underlayer as an isomorphic template for ultrathin hematite films toward efficient photoelectrochemical water splitting

Michael Graetzel, Maurin Cornuz, Kevin Sivula, Florian Le Formal, Jérémie Minh-Châu Brillet, Nicolas Tétreault, Takashi Hisatomi

Hematite photoanodes for photoelectrochemical (PEC) water splitting are often fabricated as extremely-thin films to minimize charge recombination because of the short diffusion lengths of photoexcited carriers. However, poor crystallinity caused by structu ...

2012

Solar hydrogen production with semiconductor metal oxides: new directions in experiment and theory

Michael Graetzel, Kevin Sivula, Florian Le Formal, Jérémie Minh-Châu Brillet

An overview of a collaborative experimental and theoretical effort toward efficient hydrogen production via photoelectrochemical splitting of water into di-hydrogen and di-oxygen is presented here. We present state-of-the-art experimental studies using hem ...

2012

Cathodic shift in onset potential of solar oxygen evolution on hematite by 13-group oxide overlayers

Michael Graetzel, Maurin Cornuz, Kevin Sivula, Florian Le Formal, Jérémie Minh-Châu Brillet, Nicolas Tétreault, Takashi Hisatomi

The onset potential of photoelectrochemical water oxidation on ultrathin hematite was improved by up to 200 mV by the chemical bath deposition of 13-group oxides as overlayers. It is proposed that the corundum-type overlayers released lattice strain of the ...

2011

Influence of Plasmonic Au Nanoparticles on the Photoactivity of Fe2O3 Electrodes for Water Splitting

Michael Graetzel, Florian Le Formal, Scott Charles Warren

An experimental study of the influence of gold nanoparticles on a alpha-Fe2O3 photoanodes for photoelectrochemical water splitting is described. A relative enhancement in the water splitting efficiency at photon frequencies corresponding to the plasmon res ...

American Chemical Society2011

Passivating surface states on water splitting hematite photoanodes with alumina overlayers

Michael Graetzel, Maurin Cornuz, Kevin Sivula, Florian Le Formal, Nicolas Tétreault, Thomas Moehl

Hematite is a promising material for inexpensive solar energy conversion via water splitting but has been limited by the large overpotential (0.5-0.6 V) that must be applied to afford high water oxidation photocurrent. This has conventionally been addresse ...

2011

On the Morphology and Interfaces of Nanostructured Hematite Photoanodes for Solar-Driven Water Splitting

Florian Le Formal

A sustainable route to store the energy provided by the Sun, is to directly convert sunlight into molecular hydrogen using a semiconductor performing water photolysis. Hematite (α-Fe2O3) is promising for this application due to its ample abundance, chemica ...

EPFL2011

Multi-walled carbon nanotubes functionalized by carboxylic groups: Activation of TiO2 (anatase) and phosphate olivines (LiMnPO4; LiFePO4) for electrochemical Li-storage

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Florian Le Formal

Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO2 (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO2 is improved by nanotube networking, but the Li-st ...

Elsevier2010

Examining architectures of photoanode-photovoltaic tandem cells for solar water splitting

Michael Graetzel, Maurin Cornuz, Jun Ho Yum, Kevin Sivula, Florian Le Formal, Jérémie Minh-Châu Brillet

Given the limitations of the materials available for photoelectrochemical water splitting, a multiphoton (tandem) approach is required to convert solar energy into hydrogen efficiently and durably. Here we investigate a promising system consisting of a hem ...

Cambridge University Press2010

Photoelectrochemical Water Splitting with Mesoporous Hematite Prepared by a Solution-Based Colloidal Approach

Michael Graetzel, Kevin Sivula, Florian Le Formal

Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe2O3) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostruc ...

American Chemical Society2010

Controlling Photoactivity in Ultrathin Hematite Films for Solar Water-Splitting

Michael Graetzel, Kevin Sivula, Florian Le Formal

A promising route to increase the performance of hematite (alpha-Fe2O3) photoelectrodes for solar hydrogen production through water-splitting is to use an extremely thin layer of this visible light absorber on a nanostructured scaffold. However, the typica ...

Wiley-Blackwell2010

Enhanced-Light-Harvesting Amphiphilic Ruthenium Dye for Efficient Solid-State Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Carole Graetzel, Robin Humphry-Baker, Soo-Jin Moon, Mingkui Wang, Florian Le Formal, Peng Wang

A ruthenium sensitizer (coded C101, NaRu (4,4'-bis(5-hexylthiophen-2-yl)-2,2'-bipyridine) (4-carboxylic acid-4'-caboxylate-2,2'-bipyridine) (NCS)(2)) containing a hexylthiophene-conjugated bipyridyl group as an ancillary ligand is presented for use in soli ...

Wiley-Blackwell2010

WO3-Fe2O3 Photoanodes for Water Splitting: A Host Scaffold, Guest Absorber Approach

Michael Graetzel, Kevin Sivula, Florian Le Formal

Solar hydrogen production via watersplitting with hematite (Fe2O3) has been limited by poor light absorption and a small hole diffusion length. These drawbacks can be overcome by using a high-surface-area host to support a thin layer of hematite-allowing p ...

2009

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