Development of cavity microelectrode devices and their uses in various research fields

International audienceThe cavity microelectrodes (CMEs) have been introduced in the 1990s and since then have been employed for the characterization of various types of materials ranging from materials used for energy storage, biological applications, catalysis characterization, or corrosion studies. This technique takes advantage of working on small amount of pure electroactive materials (few hundreds nanograms) using usual electrochemical techniques (cyclic voltammetry, electrochemical impedance spectroscopy, etc.) and allows a rapid screening of the electrochemical behavior of new materials. The CME development and its main applications for the electrochemistry of powder materials are reviewed and discussed

Copper-Palladium Nanoelectrocatalysts for Carbon Dioxide Reduction, International Symposium on Electrocatalysis

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Insights into the Voltammetry of Cavity Microelectrodes Filled with Metal Powders: The Value of Square Wave Voltammetry

International audienceCavity MicroElectrodes (CMEs) offer a valuable platform to evaluate the electrocatalytic performance of micro-and nano-particulate materials. The technical factors and physicochemical processes affecting the electrochemical response at CMEs are to be recognized, specifically, the accessibility of redox species to the electrocatalyst surface. With this aim, the voltammetric response of CMEs is investigated through a joint experimental and theoretical approach including a comparative study of cyclic and square wave voltammetry (SWV). Experiments reveal a capacitive distortion of the response that increases with the powder surface area, but with a faradaic response analogous to that of recessed or inlaid microdisks, i.e. with electrochemical reactions occurring essentially on the first layer of the powder load. We show that SWV is well suited to discriminate Faradaic processes at CMEs and we present accurate mathematical expressions to describe it. These results provide guidelines for the design and analysis of CME voltammetric measurements

Nanocatalyseurs Cu100-xPdx pour la réduction électrochimique du CO2

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Influence of nanosizing on hydrogen electrosorption properties of rhodium based nanoparticles/carbon composites

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Photoelectrochemical and electrochemical urea oxidation with microwave-assisted synthesized Co-Fe2O3@NiO core–shell nanocomposites

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Mesopore Formation and Silicon Surface Nanostructuration by Metal-Assisted Chemical Etching With Silver Nanoparticles

International audienceThis article presents a study on Metal-Assisted Chemical Etching (MACE) of silicon in HF-H 2 O 2 using silver nanoparticles as catalysts. Our aim is a better understanding of the process to elaborate new 3D submicrometric surface structures useful for light management. We investigated MACE over the whole range of silicon doping, i.e., p ++ , p + , p, p − , n, n + , and n ++. We discovered that, instead of the well-defined and straight mesopores obtained in p and n-type silicon, in p ++ and n ++ silicon MACE leads to the formation of cone-shaped macropores filled with porous silicon. We account for the transition between these two pore-formation regimes (straight and cone-shaped pores) by modeling (at equilibrium and under polarization) the Ag/Si/electrolyte (HF) system. The model simulates the system as two nanodiodes in series. We show that delocalized MACE is explained by a large tunnel current contribution for the p-Si/Ag and n-Si/HF diodes under reverse polarization, which increases with the doping level and when the size of the nanocontacts (Ag, HF) decreases. By analogy with the results obtained on heavily doped silicon, we finally present a method to form size-controlled cone-shaped macropores in p silicon with silver nanoparticles. This shape, instead of the usual straight mesopores, is obtained by applying an external anodic polarization during MACE. Two methods are shown to be effective for the control of the macropore cone angle: one by adjusting the potential applied during MACE, the other by changing the H 2 O 2 concentration. Under appropriate etching conditions, the obtained macropores exhibit optical properties (reflectivity ∼3 %) similar to that of black silicon

First Evidence of Rh Nano-Hydride Formation at Low Pressure

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Anisotropic Nanoporous Nickel Obtained through the Chemical Dealloying of Y 2 Ni 7 for the Comprehension of Anode Surface Chemistry of Ni‐ M H Batteries

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Iron role in the electrochemical cyclopropanation reaction of activated olefins and halogenated compounds

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