A Microfluidic Channel Flow Cell for Electrochemical ESR

The application of physics-informed neural networks to hydrodynamic voltammetry

Electrochemical problems are widely studied in flowing systems since the latter offer improved sensitivity notably for electro-analysis and the possibility of steady-state measurements for fundamental studies even with macro-electrodes.

XAS and EPR in Situ Observation of Ru(V) Oxo Intermediate in a Ru Water Oxidation Complex**

In this study, we combine in situ spectroelectrochemistry coupled with electron paramagnetic resonance (EPR) and X‐ray absorption spectroscopies (XAS) to investigate a molecular Ru‐based water oxidation catalyst bearing a polypyridinic backbone [Ru^II(OH₂)(Py₂Metacn)]²⁺. Although high valent key intermediate species arising in catalytic cycles of this family of compounds have remain elusive due to the lack of additional anionic ligands that could potentially stabilize them, mechanistic studies performed on this system proposed a water nucleophilic attack (WNA) mechanism for the O−O bond formation. Employing in situ experimental conditions and complementary spectroscopic techniques allowed to observe intermediates that provide support for a WNA mechanism, including for the first time a Ru(V) oxo intermediate based on the Py₂Metacn ligand, in agreement with the previously proposed mechanism.

Amine functionalization of N,N,N′,N′-tetramethyl-p-phenylenediamine for the electrosynthesis of a wide range of p-phenylenediamines in green conditions

An efficient derivative of TMPD is introduced by amine functionalization. Despite TMPD, two-electron oxidation of this compound is stable. This property opens a window for the electrosynthesis of new phenylenediamines in green conditions.

Novel Electrochemical Pretreatment for Preferential Removal of Nonylphenol in Industrial Wastewater: Biodegradability Improvement and Toxicity Reduction

Preferential pretreatment of nonylphenol (NP) before biological treatment is of great significance due to its horizontal gene transfer effect and endocrine disruption activity. A novel molecular imprinting high-index facet SnO₂ (MI-SnO_2, HIF) electrode is designed. NP was effectively removed from industrial wastewater at 1.8 V with totally suppressing human estrogen activity. The ratio of 5 day biological oxygen demand to chemical oxygen demand (BOD₅/COD_Cr) was enhanced to 0.412 from 0.186 after preferential pretreatment. The effluent concentration of NP was 6.4 μg L^-1 after further simulating anaerobic-anoxic-oxic treatment, which was about 1/10 of that without pretreatment. This preferential electrochemical pretreatment is interpreted as prior adsorption and enrichment of target pollutants on the MI-SnO_2, HIF surface. The reactive oxygen species and subsequent oxidation products were investigated by in situ electron paramagnetic resonance and electrochemical infrared spectroscopy. The degradation pathway of NP was further analyzed by liquid chromatography-mass spectrometry. This unique pretreatment method for a complex tannery wastewater system has irreplaceable status because no methods with similar advantages have been reported, expecting to be widely used in preferential pretreatment of toxic contaminants blended with highly concentrated nontoxic organics.

Robust non-covalent and covalent anchored N,N,N′,N’-tetramethyl-p-phenylenediamine derivative on electrode surface via spontaneous physical immobilization and in situ generated aryldiazonium ion electro-grafting: implication for on-surface chemistry and electro-catalytic determinations

Redox active electrodes were fabricated via robust adsorption and electro-grafting of an electroactive diazonium ion. The electrodes have implications in post-functionalization as well as electro-catalytic activity.

Reversed redox generation of silyl radicals in a four-electrode flow-through EPR spectroelectrochemical cell

A flow-through four-electrode EPR spectroelectrochemical cell was developed which allowed the observation of silyl radical formation in apparently multielectron electrochemical processes, in which these species could not be detected directly because of the high driving force of their further reduction/oxidation leading to non-paramagnetic products. Silyl radicals thus generated were characterized by spin trapping with alpha-phenyl-N-tert-butyl nitrone (PBN), intramolecular spin trapping or by direct detection. The overall multielectron process is realized in the first, generating, compartment of the cell and the ionic species formed are then transformed into the corresponding radicals in the second compartment via a one-electron redox process in the opposite direction, e.g. two-electron reductions of Ph(3)SiCl or Et(3)SiCl followed by one-electron oxidation of the resulting Ph(3)Si(-) or Et(3)Si(-) anions (+2e/-e process). These radical species were then identified as their secondary paramagnetic products or by their spin trapping with PBN. Using (2-[cyclohex-3-enyl]ethyl)dimethyl chlorosilane in this process, the formation of the silicon-centered radical and its intramolecular addition across the internal double bond were evidenced by spin trapping. The reduction of electrophilic silicon intermediates issued from the oxidation of Ph(3)SiSiPh(3) (-2e/+2e process) resulted in Ph(3)Si* radicals trapped with PBN. The reduction of the electrochemically prepared persistent dication of a stable disilene, thiatetrasilacyclopentene, allowed generation of a disilene cation radical characterized by EPR.