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• Electrodeposition of tellurium from deep eutectic solvents can produce nanowires. • Tellurium nanostructure is strongly dependent on deposition conditions. • Swapping chloride for iodide produces nanoplatelets in place of nanowires. • Tellurium nucleation is kinetically slower in chloride than bromide and iodide, which impacts subsequent nanostructures. Electrochemical deposition of tellurium from deep eutectic solvents (DES) at gold film electrodes produced films of tellurium nanowires. The deposition was evenly distributed over the gold surface, with an average diameter of ∼70 nm and length of ∼1 µm. Deposition was extremely sensitive to the applied potential, tellurium concentration and deposition bath temperature, with deviations away from optimised conditions preventing the formation of the desired nanostructure. Interestingly, replacing the chloride in a popular eutectic solvent with bromide or iodide had a significant impact on the resultant film structure, with bromide giving no clearly defined nanostructure but iodide giving nanoplatelets. This demonstrates a strong control of tellurium nanostructure by halide ions, offering a way to two distinct nanostructures from the same core experimental set up. [Display omitted] [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]

• Nickel cobalt nitride electrodes catalyse glucose and hydrogen peroxide redox. • Zirconium nitrides are superior to platinum/carbon for oxygen reduction. • Molybdenum nitride microdisk show great potential as electrochemical sensors. Metal nitride materials are garnering interest in many fields including electrochemistry, although they are still at an early stage of investigation and underexplored. This mini review provides insights on the latest advancements in the field of electroanalytical chemistry based on metal nitride materials, specifically focusing on the best performing transition metal nitride sensors published between 2017 and 2020 for important targets such as glucose, hydrogen peroxide and dissolved oxygen. Nickel cobalt nitride electrodes demonstrate electrocatalytic behaviours toward glucose oxidation and hydrogen peroxide reduction processes. Meanwhile, zirconium nitride electrodes could replace platinum/carbon electrodes for oxygen reduction reaction. This article also introduces solid molybdenum nitride microdisk electrodes, which can easily be prepared and maintained and show diffusion-control voltammetric responses for the complex peroxodisulfate reduction reaction. This mini review will benefit researchers who would like to delve into the potential of metal nitride electrodes as electrochemical sensors. [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]

Electrogenerated chemiluminescence (ECL) based sensors have the intrinsic advantage of having zero theoretical background signal, derived from the electrochemical initiation of the luminescence process. Since the limit of detection (LOD) for sensors is defined as three times the noise of the background over the sensitivity of the system, further improvement to an ECL based detection limit is tied to improving sensitivity. Enhancing ECL sensitivity can be achieved through optimizing the mechanistic or kinetic performance of the reagents. While the mechanism for many luminophore-coreactant pairs have been established, the kinetics for the competing homogeneous reactions responsible for photon emission have not been directly resolved. This is due to the difficulty in experimentally probing and isolating a single homogeneous reaction while multiple simultaneous heterogeneous and homogeneous reactions are occurring. Combining the techniques of spectroelectrochemistry and finite element modeling, we monitor the homogeneous reactions for the coreactant pair, tris(2,2'-bipyridine)ruthenium(II) (Ru(BPY)32+) and tripropylamine (TPA). Corresponding trends found in the experimental absorbance and theoretical concentration profiles demonstrated that the reaction between Ru(BPY)33+ and TPA• intermediates proceeds significantly faster than the other available pathways. The identification of the oxidized intermediates as the dominant electron transfer pathway implies that the screening of luminophore and coreactant pairs that increase the stability of these kinetically labile intermediates would increase ECL sensitivity and ultimately performance. [ABSTRACT FROM AUTHOR]