Computer simulation of charge-selective electrochemistry of catechols at high-surface-area carbon fibers

Galvanically Stimulated Degradation of Carbon-Fiber Reinforced Polymer Composites: A Critical Review

Carbon is used as a reinforcing phase in carbon-fiber reinforced polymer composites employed in aeronautical and other technological applications. Under polarization in aqueous media, which can occur on galvanic coupling of carbon-fiber reinforced polymers (CFRP) with metals in multi-material structures, degradation of the composite occurs. These degradative processes are intimately linked with the electrically conductive nature and surface chemistry of carbon. This review highlights the potential corrosion challenges in multi-material combinations containing carbon-fiber reinforced polymers, the surface chemistry of carbon, its plausible effects on the electrochemical activity of carbon, and consequently the degradation processes on carbon-fiber reinforced polymers. The implications of the emerging use of conductive nano-fillers (carbon nanotubes and carbon nanofibers) in the modification of CFRPs on galvanically stimulated degradation of CFRP is accentuated. The problem of galvanic coupling of CFRP with selected metals is set into perspective, and insights on potential methods for mitigation and monitoring the degradative processes in these composites are highlighted.

Effects of Substrate and Polymer Encapsulation on CO2 Electroreduction by Immobilized Indium(III) Protoporphyrin

Heterogenization of molecular catalysts for CO₂ electroreduction has attracted significant research activity, due to the combined advantages of homogeneous and heterogeneous catalysts. In this work, we demonstrate the strong influence of the nature of the substrate on the selectivity and reactivity of electrocatalytic CO₂ reduction, as well as on the stability of the studied immobilized indium(III) protoporphyrin IX, for electrosynthesis of formic acid. Additionally, we investigate strategies to improve the CO₂ reduction by tuning the chemical functionality of the substrate surface by means of electrochemical and plasma treatment and by catalyst encapsulation in polymer membranes. We point out several underlying factors that affect the performance of electrocatalytic CO₂ reduction. The insights gained here allow one to optimize heterogenized molecular systems for enhanced CO₂ electroreduction without modification of the catalyst itself.

Electrochemical flow injection analysis study of ion partitioning at high surface area carbon fiber electrodes

Charge-selective electrochemistry was previously shown to occur at high surface area carbon fibers that were produced by fracturing the outer periphery with anodic current or positive potential. The cyclic voltammetric behavior of electroactive species observed at these fibers exhibited a distinct pH dependence related to the protonation/deprotonation of oxygen-containing functional groups at the surface of the carbon fiber. In this paper, electrochemical flow injection analysis (EC-FIA) is used to probe ion partitioning in to and out of the interior microstructure of the treated carbon fiber, for both electroactive and electroinactive species. It was found that the extent of partitioning was the result of both ion charge and hydrated ionic radius, in addition to the level of fracture. It was further observed that the direction of movement for an injected ionic species could be controlled relative to the ion concentration, the pH of the carrier solution, or both. EC-FIA allowed the simultaneous observation of current due to ion movement and that due to electron transfer to a redox-active species. The results presented are consistent with a model in which fixed negatively charged sites in the interior of fractured fibers govern ion partitioning with positively charged ions in the carrier solution, with counterions located in the interior "free" volume.