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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

El Hichou, Ahmed, Diliberto, Sébastien and Stein, Nicolas
Surface and Coatings Technology, 270(0):236-242

Mots clefs: Electrodeposition Zinc oxide film Aluminum doping

Resume: Abstract Undoped and aluminum doped zinc oxide thin films were successfully deposited by electrodeposition technique from aqueous solution onto ITO substrates at optimized experimental conditions. The variations of the structural, electrical and optical properties with the doping concentration were investigated. X-ray diffraction analysis showed typical patterns of the hexagonal ZnO structure for both doped and undoped films. The films are single phase and polycrystalline with the (002) preferred orientation. The grain size, texture coefficient and optical band gap values were evaluated for different aluminum salt concentrations. The films, obtained from a 10? 7 M aluminum electrolyte, exhibit the highest crystallographic quality and lowest electrical resistivity of 2 × 10? 4 ?·cm with an energy band gap of 3.35 eV.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Li, Shen, Chaput, Laurent, Stein, Nicolas, Frantz, Cedric, Lacroix, David and Termentzidis, Konstantinos
Applied Physics Letters, 106(23):233108

Mots clefs: molecular dynamics method phonons thermal conductivity bismuth compounds nanowires

Equipe: Département CP2S : Chimie et électrochimie des matériaux

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