Jekaterina Kuleshova

TEMPO‐Mediated Electrooxidation of Primary and Secondary Alcohols in a Microfluidic Electrolytic Cell

A general procedure for the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated electrooxidation of primary and secondary alcohols modified for application in a microfluidic electrolytic cell is described. The electrocatalytic system utilises a buffered aqueous tert-butanol reaction medium, which operates effectively without the requirement for additional electrolyte, providing a mild protocol for the oxidation of alcohols to aldehydes and ketones at ambient temperature on a laboratory scale. Optimisation of the process is discussed along with the oxidation of 15 representative alcohols.

Optimization of the electrodeposition process of high-performance bismuth antimony telluride compounds for thermoelectric applications

High-quality films of bismuth antimony telluride were synthesized by electrodeposition from nitric acid electroplating baths. The influence of a surfactant, sodium ligninsulfonate, on the structure, morphology, stoichiometry, and homogeneity of the deposited films has been investigated. It was found that addition of this particular surfactant significantly improved the microstructural properties as well as homogeneity of the films with a significant improvement in the thermoelectric properties over those deposited in the absence of surfactant. A detailed microprobe analysis of the deposited films yielded a stoichiometric composition of Bi(0.35)Sb(1.33)Te(3) for the films electrodeposited in the absence of surfactant and a stoichiometry of Bi(0.32)Sb(1.33)Te(3) for films deposited in the presence of surfactant.

Correlation of microstructural properties with thermoelectric performance of Bi0.Sb1.Te3 film fabricated by electroplating

This study shows for the first time, the correlation between the microstructural properties (chemical composition and its homogeneity) and the thermoelectric properties for p-type Bi 0.5 Sb 1.5 Te 3 electroplated films (10-15 μm thickness). High microstructural quality of Bi 0.5 Sb 1.5 Te 3 electroplated films (a close to stoichiometry chemical composition with its high homogeneity elements distribution) was achieved by using an additive in the plating solution (sodium ligninsulfonate) as a surfactant agent. A fine-grained microstructure of 280 nm to 1μm has been observed for these materials, which half that of the plated films without a surfactant. The thermoelectric properties of electrodeposited Bi 0.5 Sb 1.5 Te 3 films obtained without microstructural optimisation, show modest Seebeck coefficient values of 20-120 μm/K, electrodeposited film with an optimised microstructure exhibits very high values of Seebeck coefficient of 220-300 μm/K.

Ion Track Nanolithography Using Thick Cross-Linked Poly(methyl methacrylate) 950 Photoresist

This study shows that poly(methyl methacrylate) (PMMA) 950 thick photoresist is a promising polymer for ion-track nanolithography templates for nanomaterials fabrication resulting in high aspect ratio nanostructures ranging from 100 to 500 with highly selective etch rates when using deep ultraviolet (DUV) cross linking polymerisation prior to the ion-track irradiation. DUV exposure times and post exposure hardbake conditions are crucial factors for achieving high aspect ratio structures. Exposure doses of 6600 mJ/cm2 with post exposure hardbake at 180 °C for 90 s gave promising preliminary results for high aspect ratio nanotemplates using thick layer of PMMA 950 photoresist.