Search

The front cover of the journal ChemElectroChem showcases the potential of high-throughput electrosynthesis, with a researcher collecting the products with the highest yield. This method offers the opportunity to accelerate research by optimizing existing reactions and discovering new pathways. The cover is associated with a research article by Eric McCalla, Janine Mauzeroll, and their colleagues, which provides more information on this topic. [Extracted from the article]

The present shear-force constant-distance scanning electrochemical microscope regulates tip-to-substrate distance using a phase-controlled feedback mechanism that is more sensitive than the amplitude-controlled constant-distance scanning electrochemical microscopes. Phase control responds faster to frequency perturbation and presents enhance sensitivity during distance curves under constant-distance mode.

Li-ion batteries that incorporate manganese present several advantages, including low cost and low toxicity. However, these batteries often suffer from dissolution of manganese into the electrolyte solution, severely impeding battery performance. This work describes the quantitative detection of Mn2+ ions in battery relevant environment i.e. non-aqueous electrolyte within an inert atmosphere. To this end, an electrochemical probe was fabricated using electrochemical deposition of a Hg cap onto a 25 μm Pt disk microelectrode. The Pt/Hg microelectrode was fully characterized by optical microscopy, cyclic voltammetry, scanning electrochemical microscopy. Using square wave anodic stripping voltammetry to overcome reproducibility issues with classical linear sweep anodic stripping voltammetry, Mn2+ was quantified in non-aqueous solution with a limit of detection of 14 μM. Finally, using this detection scheme, the trapping ability of aza-15-crown-5 ether and dilithium iminodiacetate was investigated. [ABSTRACT FROM AUTHOR]

The present work uses a scanning electrochemical microscopy technique to study systems containing the membrane-bound reaction center protein (RC) from the purple photosynthetic bacteria Rhodobacter spheroides to chromatophores (spherical reorganization of cell membrane following its mechanical rupture) and liposomes (reconstituted membrane systems at lower degree of complexity). Scanning electrochemical microscopy is a useful tool to investigate redox processes involving a RC, because the effective heterogeneous rate constants for the redox reaction with different mediators can be measured. The technique is also able to provide information on the role of the outer cell membrane permeation on the kinetics of the electron-transfer processes and to obtain more insight into the nature of the species involved.

The fabrication and characterization of novel micropipet probes for use in scanning electrochemical microscopy (SECM) are described. These can be used to dispense small (pL) amounts of a solution while monitoring the electrochemical response at a substrate and at a ring electrode tip on the micropipet probe. The probes were constructed by insulating gold-coated borosilicate micropipets with electrophoretic paint and exposing a ring electrode at the tip by heat treatment. Characterization of the probes was performed using scanning electron microscopy, cyclic voltammetry, and SECM approach curve experiments. Routine construction of tips with diameters of the order of 3 [micro]m was possible using this technique. The probes exhibited stable steady-state currents and positive and negative feedback approach curves that agreed with those predicted by theory. Demonstrative SECM imaging experiments were performed using a picodispenser to continuously dispense an electroactive solution (ferrocenemethanol) to the SECM cell while the probe was located within a few micrometers of a Pt substrate surface. Oxidation of the dispensed electroactive solution was performed at the substrate, and feedback currents were measured at the probe tip by holding the gold ring at a reducing potential. This mode of tip-dispensing SECM was used to obtain images of a platinum substrate electrode while monitoring both the substrate current and the feedback current at the probe.

Hg/Pt hemispherical ultramicroelectrodes (UMEs) (25-[micro]m diameter) were prepared either by electrodeposition from a mercuric ion solution or by simple contact of the Pt disk to a hanging mercury drop electrode. The two methods produced equivalent tips. Optical inspection and electrochemical characterization of these Hg tips with methyl viologen, cobalt sepulchrate trichloride, and hexamineruthenium(III) chloride confirm the hemispherical nature of the UME. The scanning electrochemical microscopy approach curves for all three redox couples over a conductive substrate fit theoretical plots for hemispherical electrodes. The numerical solution of the diffusion equations for substrate generation--tip collection (SG-TC) transients for a finite Pt disk and Hg/Pt hemispherical UME are reported and compared to experimental results. A diffusion layer approximation is presented, and diffusion coefficients are extracted from the simulation. The SG-TC results reveal the enhanced sensitivity of hemispherical UME to radial diffusion.