Towards improvement of bismuth and tellurium as a thermoelectric material for energy harvesting through nanostructuring

Abstract

It has been demonstrated that lyotropic liquid crystal templates (LLCT) with mesoporous structures can be used during electrodeposition of thin films to produce films with a mesoporous structure transferred from the LLCT. Here we report the electrodeposition of mesoporous bismuth telluride (Bi₂Te₃) films from hexagonal structured LLCTs formed from mixtures of Brij®C10 and electrolyte solution in ratios of (55:45, 50:50, 45:55). The introduction of a mesoporous nanostructure to the bismuth telluride films should improve the thermoelectric properties of the material. Optimisation of the electrolyte solutions has been carried out, studying the effects of using the metals bismuth (Bi) and tellurium (Te) and the metal salts bismuth citrate (C₆H₅BiO₇), bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O and tellurium dioxide (TeO₂) dissolved in nitric acid (HNO₃) or citric acid (C₆H₈O₇) in different ratios and concentrations. The addition of a buffer solution made of citric acid and sodium citrate (C₆H₅Na₃O₇) has also been investigated. The lyotropic liquid crystal phases present for mixtures containing different concentrations of Brij®C10 and these electrolyte solutions has been looked at, including the production of phase diagrams. The liquid crystal template mixtures have been characterised using a polarised optical microscope (POM) and wide and small angle X-ray Diffraction (XRD) and Cyclic Voltammetry (CV). The deposited thin films have been characterised using wide and small angle XRD, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX), confirming that hexagonally nanostructured thin films in the (110) orientation with a composition close to Bi₂Te₃ have been produced.

More information

Identifiers

ORCID for Iris S. Nandhakumar: orcid.org/0000-0002-9668-9126

Catalogue record

Export record