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The electrochemical reduction of CO2 continues to see significant interest as a viable means of both producing important chemical materials and lowering carbon emissions. The primary challenge to making this process economically viable is the design of catalyst, electrode and reactor components that can selectively produce just one of the many possible CO2 reduction products. In this work, we report the use of hydrophobic 1-octadecanethiol coatings at copper coated gas diffusion electrodes to enhance the production of ethylene. This thiol coating gives a substantial increase in the production of ethylene at low current densities as well as a change in the rate determining step, as indicated by the substantial reduction in the Tafel slope. The observed changes to the CO2 reduction reaction indicate that the thiol layer provides a triphasic interface within the gas diffusion electrode catalyst layer. [ABSTRACT FROM AUTHOR]

A critical review of classical and improved electrodes, electrocatalysts and reactors is provided. The principles governing the selection of electrochemical flow reactor or progression of a particular design for laboratory or pilot scale are reviewed integrating the principles of electrochemistry and electrochemical engineering with practical aspects. The required performance, ease of assembly, maintenance schedule and scale-up plans must be incorporated. Reactor designs can be enhanced by decorating their surfaces with nanostructured electrocatalysts. The simple parallel plate geometry design, often in modular, filter-press format, occupies a prominent position, both in the laboratory and in industry and may incorporates porous, 3D or structured electrode surfaces and bipolar electrical connections considering the reaction environment, especially potential- and current-distributions, uniformity of flow, mass transport rates, electrode activity, side reactions and current leakage. Specialised electrode geometries include capillary gap and thin film cells, rotating cylinder electrodes, 3-D porous electrodes, fluidised bed electrodes and bipolar trickle tower reactors. Applications span inorganic, organic electrosynthesis and environmental remediation. Recent developments in cell design: 3D printing, nanostructured, templating 3D porous electrodes, microchannel flow, combinatorial electrocatalyst studies, bioelectrodes and computational modelling. Figures of merit describing electrochemical reactor performance and their use are illustrated. Future research and development needs are suggested. [ABSTRACT FROM AUTHOR]

The field of enzymatic biosensors applied to brain electrochemistry has rapidly expanded over the last few years, thanks in part to their excellent selectivity to specific target species. Much current research is therefore focused on enhancing the electrochemical signal, which often involves the detection of stoichiometric amounts of H2O2 formed as part of the enzyme mechanism. This opens the possibility of enhancing a biosensor's performance by facilitating the H2O2 oxidation signal through surface modification. Here, we investigate the impact of the roughness of the platinum surface on the biosensor response, where rougher platinum surfaces show greater activity for H2O2 oxidation, and therefore enhanced biosensor sensitivity. Through careful manipulation of the electrode surface roughness, we are able to show a significant improvement to the LOD when using a rougher electrode surface. Additionally, we have shown that this enhanced surface roughness has no detrimental effects toward the electrode response time. This suggests that surface roughness could be a simple and easy to implement means of enhancing the sensitivity of electrode-based enzymatic biosensors, and is an important factor to consider when studying other aspects of biosensor fabrication. [ABSTRACT FROM AUTHOR]

A new type of an electrochemical flow cell designed for exchangeable ultramicroelectrodes (UMEs) is presented. The cell could be used with up to 8 different UMEs allowing one to use this cell for UME array measurements. The cell was characterized using both empirical data and finite element modeling. Au and Pt UMEs were used to detect catechol simultaneously, demonstrating the ability of this cell to be used as a sensory platform. The electroanalytical response of flow system was validated by direct measurements of H2O2 concentrations. Finally, stochastic nanoparticle measurements were successfully performed using the flow system, highlighting the future possibilities of this system for environmental monitoring. [ABSTRACT FROM AUTHOR]

Herein, we validate a novel cuvette-based approach to measure electrogenerated chemiluminescence (ECL) by employing the hyphenation of a commercial spectrometer and a potentiostat. The new experimental design provides simultaneous acquisition of electrochemical and ECL data, allowing complementary analysis by both techniques. Preliminary analysis of an organometallic ECL standard, tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+), and tripropylamine (TPA), showed excellent reproducibility both in terms of the electrochemistry and the ECL signal. Equally as important, the acquired electrochemistry and ECL from the Ru(bpy)32+/TPA system served as a baseline for evaluating the ECL response of polymerizable ruthenium luminophores. [ABSTRACT FROM AUTHOR]

d-Serine acts as an endogenous co-agonist for N-methyl- d-aspartate receptors at synapses, making it essential for proper brain development and function. This amino acid has also been linked to several neurodegenerative diseases such as Alzheimer's disease and dementia. Nevertheless, the primary site and mechanism of d-serine release remains unclear. We recently demonstrated the use of an enzymatic amperometric biosensor for the in vivo quantification of endogenous d-serine release in Xenopus laevis tadpoles. Herein, we investigate the effect of the permselective poly( meta-phenylenediamine) electropolymerization conditions on the biosensor's response time and selectivity. Scanning electrochemical microscopy (SECM) is then used with the optimized biosensor to measure localized release of d-serine from a model system. This SECM methodology, which provides high spatial and temporal resolution, could be useful to investigate the primary site and mechanism of d-serine release in other biological samples. [ABSTRACT FROM AUTHOR]

In sampled-current voltammetry (SCV), current transients acquired after stepping the potential along the redox wave of interest are sampled at a fixed time to produce a sigmoidal current--potential curve akin to a pseudo steady state voltammogram. Repeating the sampling for different times yields a family of sampled-current voltammograms, one for each time scale. The concept has been used to describe the current--time-potential relationship at planar electrodes but rarely employed as an electroanalytical method except in normal pulse voltammetry where the chronoamperograms are sampled once to produce a single voltammogram. Here we combine the unique properties of microdisk electrodes with SCV and report a simple protocol to analyze and compare the microdisk sampled-current voltammograms irrespective of sampling time. This is particularly useful for microelectrodes where cyclic voltammograms change shape as the mass transport regime evolves from planar diffusion at short times to hemispherical diffusion at long times. We also combine microdisk sampled-current voltammetry (MSCV) with a conditioning waveform to produce voltammograms where each data point is recorded with the same electrode history and demonstrate that the waveform is crucial to obtaining reliable sampled-current voltammograms below 100 ms. To facilitate qualitative analysis of the voltammograms, we convert the current--potential data recorded at different time scales into a unique sigmoidal curve, which clearly highlights kinetic complications. To quantitatively model the MSCVs, we derive an analytical expression which accounts for the diffusion regime and kinetic parameters. The procedure is validated with the reduction of Ru(NH3)63+, a model one electron outer sphere process, and applied to the derivation of the kinetic parameters for the reduction of Fe3+ on Pt microdisks. The methodology reported here is easily implemented on computer controlled electrochemical workstations as a new electroanalytical method to exploit the unique properties of microelectrodes, in particular at short times. [ABSTRACT FROM AUTHOR]

CO 2 reduction offers an attractive alternative green synthetic route for ethylene, especially where CO 2 could be sourced from industrial exhausts and in combination with green power sources. However, practical applications are currently limited due to the unfortunately low selectivity of cathode materials towards ethylene. This work uses polymers with intrinsic microporosity (PIMs) to improve the performance of copper gas diffusion electrodes for CO 2 reduction to ethylene. We report an improved selectivity and activity towards ethylene with the addition of a thin PIMs layer, which is seen as improved Faradaic efficiency, increased stability and a shift in the reduction to lower overpotential. This improvement is highly dependent on the thickness of the added polymer layer, with too thick a layer having a detrimental impact on the hydrophobicity of the gas diffusion layer. With a compromise in loading, PIMs can be used to enhance the activity and selectivity of catalysts for targeted CO 2 reduction to ethylene. Image 10694 • Gas diffusion electrodes allow CO 2 reduction to ethylene, but selectivity is low. • Polymers with intrinsic microporosity can increase ethylene production. • Using too much polymer has a detrimental impact. • A compromise polymer thickness increases ethylene yield and electrode stability. [ABSTRACT FROM AUTHOR]