Electrochemical conversion of glassy carbon into a poly-nucleophilic reactive material. Applications for carbon chemical functionalization. A mini-review

2015

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The reduction of solutions of carbon dioxide (saturated at the room temperature in organic polar solvents such as acetonitrile, AN, or N,N-dimethylfomamide, DMF, containing tetraalkylammonium salts TAAX) was achieved at smooth silver electrodes. Under these conditions, reduction steps were obtained beyond -1.7 V vs Ag / AgCl with exact potentials depending on the size of TAA + cations. An unexpected behaviour is noticeable with tetramethylammonium salts (TMA + X -) leading to a progressive electrode inhibition upon scans or fixed potential electrolysis at E < -2V. These results are in agreement with the formation of a thick layer of the form {Ag-CO 2 -,TMA + } strongly sensitive to di-oxygen, water, organic π-acceptors; this layer is considered as a reducing reagent of low chemical stability and can be oxidized before silver. Placed under pure argon atmosphere, the layer decomposes -presumably by instability of TMA + in reducing media that permits trapping of large superficial amounts of CO 2 in the material supposing the formation of multi-layers of CO 2 (up to 5´10 -6 mol cm -2 ). These novel {silver-CO 2 } materials could be seen as dual catalytic-electrophilic electrodes.

Section: Resultsmentioning

confidence: 73%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Electrochemical insertion of CO 2 into silver in a large extent

2015

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“…Voltammetric and coulometric measurements were performed using three-electrode cells separated with a fritted glass. The electrochemical instrumentation has been previously reported [7].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Fixed potential reduction and exfoliation of natural graphite by bulky ammonium salts has been reported [6]. The electrochemical synthesis of those "graphite salts", rather similar to {TAA-amalgams}, has to be considered both as a novel generation of reducing species and as poly-nucleophilic materials (then reactive with organic reagents for modification of graphites and carbons [7]). …”

Section: Introductionmentioning

confidence: 99%

Electrochemical exfoliation in real time of natural graphite deposited onto glassy carbon. Doping and modifying carbons through ultra-thin graphite layers

2014

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To cite this version:Jacques Simonet. Electrochemical exfoliation in real time of natural graphite deposited onto glassy carbon. Doping and modifying carbons through ultra-thin graphite layers. Electrochemistry Communications, Elsevier, 2014, 48, pp.142 -146. <10.1016/j.elecom.2014.08.031>. A C C E P T E D M A N U S C R I P T Rennes Cedex, France. ACCEPTED MANUSCRIPT AbstractNatural graphite, deposited onto smooth glassy carbon, when reduced (around -2V vs.Ag/AgCl) in the presence of tetraalkylammonium salts (TAAX) in aprotic polar solvents, lead to spectacular exfoliation processes followed in real time in the course of voltammetric scans.The method permits to get extraordinary stable modified carbon surfaces, with quite simple voltammetric responses (1 to 4 reversible cathodic steps) that strongly depend on the nature of the cations used. Those cathodic steps exhibit currents quasi perfectly proportional to the scan rate. It is expected the formation of a graphene-like substrate. Surface modifications both by ferrocene and anthraquinone could underline the originality of those new materials

“…The nature of metal and ion-pairs formed with the counter-ion of supporting electrolyte should be considered here. We might expect that carbon dioxide is scheming in this context because its apparent reduction potential is very dependant on the electrode material and on the supporting electrolyte; it certainly obeys catalytic rules already observed with many solid conducting materials such as glassy carbon [11], graphite [12], graphene [13], and lead [14,15].…”

Section: Introductionmentioning

confidence: 99%

Cathodic carboxylation of gold in thick {Au-CO2}n layers. A model for reversible electrochemical sequestration of CO2

Jouikov

2015

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To cite this version:Viatcheslav Jouikov, Jacques Simonet. Cathodic carboxylation of gold in thick Au-CO2n layers. A model for reversible electrochemical sequestration of CO2. Electrochemistry Communications, Elsevier, 2015Elsevier, , 59, pp.40-42. <10.1016Elsevier, /j.elecom.2015.06.020>. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractCatalytic reduction of CO 2 (saturated in organic polar solvents, e.g. N,N-dimethylfomamide, containing Me 4 NX or NaBF 4 ) was achieved at smooth gold electrodes and at glassy carbon electrodes galvanostatically capped with a thin layer of gold. Under these quite explicit conditions, very sharp reduction steps were observed near -1.5 V vs. Ag/AgCl. With small cations listed above, an unexpected behaviour was observed, a progressive electrode inhibition occurring upon several scans or after a fixed-potential electrolysis at E < -1.7 V. This phenomenon could be attributed to the insertion of CO 2 into gold, leading to the formation of a thick iono-metallic multi-strata layer (less conducting than pure metal) that grows with the electrode charge. The formation of this new interface is due to the concur of three elements: transient CO 2 anion radical, the metal, and rather small-sized cations (M + = Na + or TMA + ), the three possibly associated in a form {Au-CO 2 -,M + } apparently very reactive with oxygen, moisture, and with some organic π-acceptors. Upon multi-scans up to -2.2 V, the thickness of formed layer progressively increases reaching more than 10 -7 to 10 -6 mol cm -2 . Such multi-layers undergo decomposition in the anodic domain at about +1.7 V liberating CO 2 beforehand trapped in Au. Coulometric analyses demonstrated that insertion (cathodic) and release (anodic) steps are quite equivalent, which permits to consider this process as chemically reversible sequestration of carbon dioxide.