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Olympiades de la Chimie

Rencontre avec les lycéens - Olympiades de la Chimie 2022

Publication dans Bioelectrochemistry

Understanding and sensing microbial biofilm formation onto surfaces remains highly challenging for preventing corrosion and biofouling processes. For that purpose, we have thoroughly investigated biofilm formation onto glassy carbon electrode surfaces by using electrochemical technics. Pseudomonas aeruginosa was studied because of its remarkable ability to form biofilms in many environments. The modification of the electrode-solution interface during biofilm growth was monitored by in-situ measurement of the open-circuit potential and correlated with results obtained by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy and bioassays. The sensing of the biofilm formation hence suggests a multi-steps mechanism, which may include pre-formation of an insulating layer onto the surface prior to the bacteria adhesion and biofilm formation.

Séminaire équipe SPECTRE

Prochains séminaires: 07 nov. 2022 (Mahdi SAAD), 28 nov. 2022 (Alexandre LEBON), 05 déc. 2022 (Karunamay MAJEE), 12 déc. 2022 (Christophe ORAIN)

Front Cover ARt of Dalton Trans.

Dalton Transaction, Volume 51, Issue 16

Publication dans Electrochimica Acta

Copper (Cu) sensing in the nanomolar range is an important challenge for marine water monitoring, especially with eco-friendly materials and reagents. For this purpose, electrochemical Cu(II) sensors appear as fully suitable because of their relatively high sensitivity, selectivity and adaptability for in situ measurements. So far, one of the usual electrochemical methods for Cu(II) sensing is adsorptive anodic stripping voltammetry (AdASV), since it offers a good selectivity, accumulation at open circuit potential and a reliable analytical response for concentrations above 10 nmol.L−1. Surprisingly, no work has ever addressed an electrocatalytic procedure to enhance the electrochemical copper sensing and allowed detection below 10 nM. Thus, we have developed an original two-step strategy based on the surface modification of pencil graphite electrodes (PGE) with p-aminobenzyl-C-functionalized cyclam, a strong chelating ligand for Cu(II), as well as the use of a simple reaction which can be electrocatalyzed by Cu such as HER (Hydrogen Evolution Reaction) to finally determine the accumulated amount of copper catalyst on the PGE. We show here that (i) a well-defined diffusion-limited catalytic peak can be obtained from cyclic voltammetry (CV) experiments with Cu(II)-cyclam-modified PGE, (ii) this HER peak potential is correlated to copper surface concentration, which can be sensed at the same time by adsorptive anodic stripping voltammetry and (iii) peak shift analysis (SA) of the voltammetric curves is a more sensitive method than the commonly used stripping voltammetry to reveal copper accumulation at modified PGE. Indeed, the limit of detection (LOD) reached with this method is one order of magnitude lower compared to AdASV (LOD = 1.1 nM and 16 nM, respectively). These results illustrate the ability of electrocatalysis to be a relevant tool under certain conditions for metal trace detection through

Publication dans Chemical Communications

We present here a novel strategy based on the covalent grafting of a C-functionalized Ni–cyclam complex onto glassy carbon to achieve heterogeneous electrocatalytic CO2 reduction in neutral water at low overpotential (−500 mV vs. NHE), with moderate turnover number (TON = 454), high selectivity (85% CO produced) and good faradaic efficiency (56% CO). Direct comparison with the N-functionalized Ni–cyclam analogue highlights the benefits of this approach in terms of CO2 electroreduction.

Front Cover Art of Chem. Commun.

Chemical Communications, Volume 58, Issue 48