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Publications: Articles

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References par page: Mots clefs Voir les resumes


Rostek, Raimar, Stein, Nicolas and Boulanger, Clotilde
Journal of Materials Research, 30(17):2518-2543

Mots clefs: electrodeposition,thermoelectricity,microscale devices

Resume: Starting with the first published works on the electrochemical deposition of thermoelectric (TE) V–VI compounds in the early nineties, these past two decades have seen a steady increase in scientific interest and publications on this topic. This is hardly surprising, as TE devices offer unique opportunities for power generation in virtually any environment (“energy harvesting”) or demanding cooling applications through the Peltier effect. This review first provides an overview of the advances in the electrodeposition of n- and p-type thin films based on Bi2(Te, Se)3 and (Bi, Sb)2Te3, the currently best-known TE materials for room temperature applications. The overview includes information about the electrolyte and the deposition conditions as well as the achieved composition, thickness, morphology, and TE properties of the deposited films. Additionally, we present the state-of-the-art and recent developments in electroplating-based fabrication processes for microscale TE devices.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Braghiroli, F. L., Fierro, V., Szczurek, A., Stein, N., Parmentier, J. and Celzard, A.
Ind. Crops Prod., 70:332-340

Resume: Six porous carbon materials, produced by hydrothermal treatment of flavonoid tannin and subsequent carbonization at 1173 K, were tested as electrodes of supercapacitors. Four of these carbons were doped with nitrogen by putting tannin in contact with ammonia before or during the hydrothermal treatment. The pyrolyzed hydrothermal carbons had moderate surface areas, within the range 442-684 m2 g-1, and nitrogen contents ranging from 0.7 to 8.0 wt.%. Specific capacitances as high as 320 F g-1 and normalized capacitances as high as 58 ?F cm-2 were measured at 2 mV s-1. These performances are comparable with those obtained with high surface area-activated carbons, whereas, normalized capacitances values are among the highest ever reported. Mesostructuration, within the range 3-13 nm, of these materials appears to be a good strategy to improve their electrochem. performances at higher scan rates. We confirmed the beneficial role of oxygen up to 18 wt.%, while an optimum in nitrogen content exists from 3 to 6 wt.%. [on SciFinder(R)]

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Zimmer, Alexandre, Broch, Laurent, Boulanger, Clotilde and Stein, Nicolas
Electrochimica Acta, 174(0):376-383

Mots clefs: In-situ ellipsometry nucleation electrocrystallization first steps of electrodeposition bismuth telluride

Resume: Abstract An optical-electrochemical study on the initial stages of bismuth telluride (Bi2Te3) electrodeposition onto gold substrate is presented in this work. Numerical methods were applied on both electrochemical and optical data to obtain the relevant kinetic parameters from electrocrystallization theoretical equations and ellipsometric models in order to describe this system in the relevant 0-15 seconds range. The in-situ ellipsometry and electrodeposition analysis reveals a three-step mechanism. After an induction time including the double layer charge, the formation of a monolayer of tellurium is highlighted, followed by the adatom surface diffusion. Then, the growth of three-dimensional Bi2Te3 crystallites is observed according a progressive nucleation and a linear growth rate. Experimental and theoretical details about each technique are given and analyzed.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Braghiroli, F. L., Fierro, V., Szczurek, A., Stein, N., Parmentier, J. and Celzard, A.
Carbon, 90(0):63-74

Resume: Abstract Aminated tannin submitted to hydrothermal treatment led to nitrogen-doped gels in the absence of any cross-linker. Such gels were subcritically dried, freeze-dried or supercritically dried to obtain organic xerogels, cryogels and aerogels, respectively, having nitrogen contents between 3.0 and 3.7 wt.%. After pyrolysis at 900 °C, the materials presented nitrogen contents ranging from 1.9 to 3.0 wt.%, and surface areas as high as 860, 754 and 585 m2 g?1 for carbon aerogels, cryogels and xerogels, respectively. All of them displayed micropores associated with different mesopore volumes, depending on both the drying method and initial dilution of the precursor. When tested as supercapacitor electrodes, these carbon gels presented outstanding specific and normalised capacitances, up to 387.6 F g?1 and 69.5 ?F cm?2, respectively, at a scan rate of 2 mV s?1 in 4 mol L?1 H2SO4 aqueous solution. These performances are higher than those obtained with high apparent surface area-activated carbons, as the measured capacitances are indeed among the highest ever reported. The influence of nitrogen- and oxygen-based moieties was investigated, and optimal N and O contents of 2–3 and 17–18 wt.%, respectively, were observed.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Chang, Taehoo, Cho, Sungmee, Kim, Jeongmin, Schoenleber, Jonathan, Frantz, Cedric, Stein, Nicolas, Boulanger, Clotilde and Lee, Wooyoung
Electrochimica Acta, 161:403-407

Resume: In this study, we examd. individual bismuth telluride nanowires (NWs) electrodeposited in polycarbonate membranes (PCM) used as sacrificial templates. It has been demonstrated that the compn. of Bi2Te3 is controlled by the electrodeposition conditions, e.g. the applied potential. High-resoln. transmission electron microscopy (HRTEM) shows that the av. grain size of NWs increases with increasing Te content. Our results also reveal that the electrodeposited bismuth telluride NWs are n-type, and their elec. cond. increases with increasing Te content. These NWs also demonstrated a max. power factor of 195.8 mW/m·K2 for the Te-rich NW (d = 162 nm) at 300 K. [on SciFinder(R)]

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Escande, Vincent, Petit, Eddy, Garoux, Laetitia, Boulanger, Clotilde and Grison, Claude
ACS Sustainable Chemistry & Engineering,

Resume: A novel Mn-derived catalyst was prepared starting from biomass of Mn-hyperaccumulating plants growing on metal-rich soils. Recovery of this biomass as value-added ?ecocatalysts? provides incentives for the development of phytoextraction programs on soils degraded by mining activities. Characterization of the resulting plant-based ?Eco-Mn?? catalyst by inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF) and X-ray photoelectron spectroscopy (XPS) demonstrated the presence of unusual polymetallic complexes of Mn(II) in the catalyst, along with Fe(III). Incorporation of these species into montmorillonite K10 as solid support provided a supported Eco-Mn? catalyst, whose properties were investigated for alkene epoxidation with H2O2 (30 wt%)/NaHCO3 (0.2 M) as a green terminal oxidizing reagent. The supported Eco-Mn? catalyst demonstrated a high efficiency for styrene epoxidation, with only 0.31 mol% of Mn, a much lower content of Mn than in previously described Mn-derived heterogeneous catalysts. Whereas Fe was also present in the supported Eco-Mn? catalyst, comparison experiments showed that Fe had only a limited role in the catalysis. The water content in the reaction medium had a beneficial effect, increasing the reaction efficiency. The supported Eco-Mn? catalyst was recycled four times without any loss of activity. Comparison of its properties to those of heterogeneous catalysts made by incorporation of commercial MnCl2.4H2O and FeCl3.6H2O highlighted the superior catalytic activity of polymetallic species present in the biosourced catalyst. The substrate scope of the method was extended to various alkenes, including bulky natural products, which were epoxidized with high yields (up to 99%), sometimes much higher than those obtained with already described Mn-derived heterogeneous catalysts. Finally, by simple adjustments of reaction conditions, the method allowed controlled access to aldehydes by oxidative cleavage of various styrene-derived substrates (up to 93% yield). The method thus constitutes a valuable alternative not only to classical epoxidation reagents, but also to oxidative cleavage of styrene-derived molecules, which usually involves toxic and hazardous reagents.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

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