F. Gelb, V. Keller, N. Sojic, D. Zigah, T. Cottineau
Sustainable Energy & Fuels, 2020, 4, 1099-1104
Herein, we report a new approach that allows a fast investigation of the influence of the thickness of a TiO2 photoelectrochemical film. For this we developed a simple anodization method that allows to grow, in one step, on a single titanium electrode, aligned TiO2 nanotubes with length changing gradualy between 0 to 10 μm. We were able to tune the length of the tubes by controling the immersion time within the electrolyte during the synthesis. To determine the optimal length of the nanotubes for photoelectrochemical application, the response of these electrodes was localy analysed using Scanning Photo-ElectroChemical Microscopy.
M.C. Tatry, Y. Qiu, V. Lapeyre, P. Garrigue, V. Schmitt, V. Ravaine
J. Colloid Interface Sci. 2020 (561), 481-493, doi.org/10.1016/j.jcis.2019.11.023
Hypothesis
Pickering emulsions stabilized by soft and responsive microgels can demulsify on demand upon microgel collapse. The concept has been explored with simple model microgels such as poly(N-isopropylacrylamide) (pNIPAM) and their derivatives, but the role of functionalization is largely unexplored.
Experiments
Saccharide-responsive phenylboronic-modified microgels are used as Pickering emulsion stabilizers. Emulsion stability and microgel organization at drop surface are studied as a function of saccharide concentration. Better insight into their behavior at interfaces is gained through adsorption kinetics and Langmuir film studies at air-water interface.
Findings
The functionalization of water-swollen microgels by phenylboronic functions imparts some hydrophobicity to the structure, at the origin of additional internal cross-links analogous which rigidify the structure compared to non-functionalized microgels, as proved by their slow adsorption kinetics and poor interfacial compressibility. Upon boronate ester formation with diol groups of the saccharide, the hydrophobic character of the phenylboronic acid decreases, increasing the adsorption kinetics and their interfacial compressibility. Emulsions are stable in the presence of saccharide, given the high deformability of the yet-hydrophilic microgels, and mechanically unstable with less deformable particles in low saccharide concentration. The hydrophobic-hydrophilic switch acts as a trigger to tune the microgel stabilizing properties.
A. Villarroel Marquez, G. Salinas, M. Abarkan, M. Idir, C. Brochon, G. Hadziioannou, M. Raoux, A. Kuhn, J. Lang, E. Cloutet
Macromol. Rapid Commun. 2020, 41, 2000134 (Back Cover)
An approach providing cation selective PEDOT:polyelectrolyte mixed conductors is presented in this communication, based on the structural modification of this ambivalent (ionic and electronic conductive) polymer complex. First, a 18-crown-6 moiety was integrated into the styrene sulfonate monomer structure as a specific metal cation scavenger particularly targeting K+ detection. This newly functionalized monomer has been characterized by 1H- NMR titration to evaluate the ion selectivity. Aqueous PEDOT dispersion inks containing the polymeric ion-selective moieties have been designed and their electrical and electrochemical properties have been analyzed. These biocompatible inks are the first proof-of-concept step towards the targeted selectivity in view of their interfacing with biological cells and microorgans of interest in the field of biosensors and physiology.
Bastien Tassy, Alice L Dauphin, Hiu Mun Man, Hugo Le Guenno, Elisabeth Lojou, Laurent Bouffier, Anne de Poulpiquet.
Abstract: Getting information about the fate of immobilized enzymes and the evolution of their environment during turnover is a mandatory step toward bioelectrode optimization for effective use in biodevices. We demonstrate here the proof-of-principle visual characterization of the reactivity at an enzymatic electrode thanks to fluorescence confocal laser scanning microscopy (FCLSM) implemented in situ during the electrochemical experiment. The enzymatic O2 reduction involves proton-coupled electron transfers. Therefore, fluorescence variation of a pH-dependent fluorescent dye in the electrode vicinity enables reaction visualization. Simultaneous collection of electrochemical and fluorescence signals gives valuable space- and time-resolved information. Once the technical challenges of such a coupling are overcome, in situ FCLSM affords a unique way to explore reactivity at the electrode surface and in the electrolyte volume. Unexpected features are observed, especially the pH evolution of the enzyme environment, which is also indicated by a characteristic concentration profile within the diffusion layer. This coupled approach also gives access to a cartography of the electrode surface response (i.e., heterogeneity), which cannot be obtained solely by an electrochemical means.
A. Karajic, P. Merzeau, E. Suraniti, S. Gounel, C. Jaillet, A. Kuhn, N. Mano
ACS Applied Energy Materials, 2020, 3, 5, 4441–4448
Biofuel cells (BFCs) are electrochemical devices that rely on the transformation of chemical energy into electricity through biochemical pathways, however delivering only modest or low power and voltage. This intrinsic limitation narrows their potential applications for driving electronics and thermodynamic systems with higher energy demands than what can be delivered by the BFCs alone. Nevertheless, coupling BFCs to electronic circuits, able to raise their voltage, allows circumventing these drawbacks. In this proof-of-concept study, we demonstrate an unconventional way of achieving highly efficient electrochemical corrosion protection of an iron surface in a chloride rich medium. The required protecting cathodic potential is generated by a self-powered bioelectronic system, consisting of a BFC, which can, despite its low voltage output (0.3V), completely prevent interfacial corrosion if it is combined with an electronic boost converter.
- Oscillatory Light-Emitting Biopolymer based Janus Microswimmers
- Chemo- and Magnetotaxis of Self-Propelled Light-Emitting Chemoelectronic Swimmers
- Remote Actuation of a Light‐Emitting Device Based on Magnetic Stirring and Wireless Electrochemistry
- L’électrochimie : une technique alternative de mesure du SO2 dans le vin ?