3. ja 5. klasside õpetajate meetodid õpilaste lugemishuvi hoidmiseks tunni siseselt ja soovitusliku kirjandusega

https://www.ester.ee/record=b5510489*es

Electrochemistry at carbon nanotube forests : sidewalls and closed ends allow fast electron transfer

The electrochemical properties of the closed ends and sidewalls of pristine carbon nanotube forests are investigated directly using a nanopipet electrochemical cell. Both are shown to promote fast electron transfer, without any activation or processing of the carbon nanotube material required, in contrast to the current model in the literature

Metallic modified (bismuth, antimony, tin and combinations thereof) film carbon electrodes.

In this paper in situ bismuth, antimony, tin modified electrodes and combinations thereof are explored towards the model target analytes cadmium(II) and lead(II), chosen since they are the most widely studied, to explore the role of the underlying electrode substrate with respect to boron-doped diamond, glassy carbon, and screen-printed graphite electrodes. It is found that differing electrochemical responses are observed, dependent upon the underlying electrode substrate. The electrochemical response using the available range of metallic modifications is only ever observed when the underlying electrode substrate exhibits relatively slow electron transfer properties; in the case of fast electron transfer properties, no significant advantages are evident. Furthermore these bismuth modified systems which commonly employ a pH 4 acetate buffer, reported to ensure the bismuth(III) stability upon the electrode surface can create create a problem when sensing at low concentrations of heavy metals due to its high background current. It is demonstrated that a simple change of pH can allow the detection of the target analytes (cadmium(II) and lead(II)) at levels below that set by the World Health Organisation (WHO) using bare graphite screen-printed electrodes

Soft X ray spectroscopy of light elements in energy storage materials

The increasing demand for electrochemical energy storage devices continuously promotes the development of new electrode materials and electrolytes. As a result, understanding their structural and electronic properties affecting electrochemical performance becomes crucial. The role of light elements, which are found in anode and cathode materials, in electrolytes and hence in the solid-electrolyte interphases, requires a special attention. Soft X-ray spectroscopies are particularly relevant to probe selectively light elements in complex environment. Here, the recent advances in the characterization of light elements in energy storage materials by soft X-ray spectroscopy and microscopy techniques are reviewed. After introducing the main X-ray spectroscopic methods and their application to ex situ/in situ/operando characterization of electrochemical processes, the role of light elements in the electrode for supercapacitors and Li/Na-ion storage applications is described. The characterization of electrolytes and related ion solvation is then briefly reviewed before describing how the formation and evolution of solid-electrolyte interphases can be monitored with these methods. Finally, major challenges and future opportunities for soft X-rays spectroscopy in the context of electrochemical energy storage are highlighted