Low‐Voltage Gaseous HCl Electrolysis with an Iron Redox‐Mediated Cathode for Chlorine Regeneration

Gaseous HCl as a by‐product is often produced from chlorination processes using Cl₂ gas. Onsite Cl₂ regeneration from HCl is highly desirable as it eliminates the need to buy new Cl₂ and dispose HCl waste. A gaseous HCl electrolysis with Fe³⁺/Fe²⁺ redox‐mediated cathode is demonstrated for Cl₂ regeneration. HCl is oxidized to generate Cl₂ and protons in the anode while Fe³⁺ is reduced to Fe²⁺ in the cathode. Simultaneously Fe³⁺ is regenerated by chemical oxidation of Fe²⁺ by oxygen (air) that also produces water. A low operational voltage and high coulombic efficiency are achieved by using a novel composite porous membrane and hydrophobic anode. Specifically, a cell voltage of only 0.64 V is needed at the typical current density of 4 kA m⁻², leading to a low energy consumption of 483 kWh per ton of Cl₂ (124 kJ mol ⁻¹) which is about 50–55 % of state‐of‐the‐art HCl electrolysis processes.     

A Redox‐Active Binder for Electrochemical Capacitor Electrodes

A promising strategy for increasing the performance of supercapacitors is proposed. Until now, a popular strategy for increasing the specific capacity of the electrode consists of grafting redox molecules onto a high surface area carbon structure to add a faradaic contribution to the charge storage. Unfortunately, the grafting of molecules to the carbon surface leads to a dramatic decrease of the electrochemical performances of the composite material. Herein, we used the organic binder as an active material in the charge/discharge process. Redox molecules were attached onto its polymeric skeleton to obtain a redox binder with the dual functionalities of both the binder and the active material. In this way, the electrochemical performance was improved without detrimentally affecting the properties of the porous carbon. Results showed that the use of a redox binder is promising for enhancing both energy and power densities.     

Rational Design of a Redox‐Labeled Chiral Target for an Enantioselective Aptamer‐Based Electrochemical Binding Assay

A series of redox‐labeled L ‐tyrosinamide (L ‐Tym) derivatives was prepared and the nature of the functional group and the chain length of the spacer were systematically varied in a step‐by‐step affinity optimization process of the tracer for the L ‐Tym aptamer. The choice of the labeling position on L ‐Tym proved to be crucial for the molecular recognition event, which could be monitored by cyclic voltammetry and is based on the different diffusion rates of free and bound targets in solution. From this screening approach an efficient electroactive tracer emerged. Comparable dissociation constants K_d were obtained for the unlabeled and labeled targets in direct or competitive binding assays. The enantiomeric tracer was prepared and its enantioselective recognition by the corresponding anti‐D ‐Tym aptamer was demonstrated. The access to both enantiomeric tracer molecules opens the door for the development of one‐pot determination of the enantiomeric excess when using different labels with well‐separated redox potentials for each enantiomer.     

Magnetless Device for Conducting Three‐Dimensional Spin‐Specific Electrochemistry

Electron spin states play an important role in many chemical processes. Most spin‐state studies require the application of a magnetic field. Recently it was found that the transport of electrons through chiral molecules also depends on their spin states and may also play a role in enantiorecognition. Electrochemistry is an important tool for studying spin‐specific processes and enantioseparation of chiral molecules. A new device is presented, which serves as the working electrode in electrochemical cells and is capable of providing information on the correlation of spin selectivity and the electrochemical process. The device is based on the Hall effect and it eliminates the need to apply an external magnetic field. Spin‐selective electron transfer through chiral molecules can be monitored and the relationship between the enantiorecognition process and the spin of electrons elucidated.     

Electrochemical Arylation of Electron‐Deficient Arenes through Reductive Activation

An electrochemical method has been developed to achieve arylation of electron‐deficient arenes through reductive activation. Various electron‐deficient arenes and aryldiazonium tetrafluoroborates are amenable to this transformation within the conditions of an undivided cell, providing the desired products in up to 92 % yield. Instead of preparing diazonium reagents, these reactions can begin from anilines, and they can be carried out in one pot. Electron paramagnetic resonance studies indicate that cathodic reduction of quinoxaline occurs using the transformation. Moreover, cyclic voltammetry indicates that both quinoxaline and aryl diazonium salt have relatively low reduction potentials, which suggests they can be activated through reduction during the reaction.