ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10–20 nm), cavity, or ultra-thin-walled tubes (2–5 nm) can be achieved.

•Bi2Te3 films were synthesized by pulsed electrodeposition on 1cm2 nickel at a deposition rate of ~ 50 μm/hour.•Film thicknesses of 800 microns were achieved on nickel with a homogenous and stoichiometric composition through the thickness of the material•All deposits produced were n-type with a Seebeck coefficient of up to -80 μV/K and an electrical conductivity of ~ 330 S cm-1 at room temperature.•First study that reports deposition of Bi2Te3 at these thicknesses onto nickel•Very important as nickel acts as a diffusion barrier in commercial TE devices which are based on bismuth tellurideBismuth telluride (Bi2Te3) is the currently best performing thermoelectric (TE) material in commercial TE devices for refrigeration and waste heat recovery up to 200 °C. Up to 800 μm thick, compact, uniform and stoichiometric Bi2Te3 films were synthesized by pulsed electrodeposition from 2 M nitric acid baths containing bismuth and tellurium dioxide on 1 cm2 nickel (Ni) substrates at average film growth rates of ~ 50 μm/h. Pre-treatment of the Ni substrate was found to significantly enhance the adhesion of Bi2Te3 material onto Ni while pulsed electrodeposition was used to increase the compactness of the material. To maintain a homogeneous composition across the thickness of the films, a sacrificial Bi2Te3 anode was employed. All deposits produced were n-type with a Seebeck coefficient of up to − 80 μV/K and an electrical conductivity of ~ 330 S/cm at room temperature.

Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi2Te3) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi2Te3 films with a high Seebeck coefficient of up to −200 μV K−1 and a high electrical conductivity of up to 400 S cm−1 resulting in a power factor of 1.6 × 10−3 W m−1 K−2 at film growth rates of 100 μm h−1 for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD.

ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10–20 nm), cavity, or ultra-thin-walled tubes (2–5 nm) can be achieved.

We report the synthesis of highly crystallographically textured films of stoichiometric bismuth telluride (Bi2Te3) in the presence of a surfactant, sodium lignosulfonate (SL), that resulted in the improved alignment of films in the (110) plane and offered good control over the morphology and roughness of the electrodeposited films. SL concentrations in the range 60–80 mg dm–3 at a deposition potential of −0.1 V vs SCE (saturated calomel electrode) were found to yield the most improved crystallinity and similar or superior thermoelectric properties compared with results reported in the literature.

High density p-type Bi0.5Sb1.5Te3nanowire arrays are produced by a combination of electrodeposition and ion-track lithography technology. Initially, the electrodeposition of p-type Bi0.5Sb1.5Te3 films is investigated to find out the optimal conditions for the deposition of nanowires. Polyimide-based Kapton foils are chosen as a polymer for ion track irradiation and nanotemplating Bi0.5Sb1.5Te3nanowires. The obtained nanowires have average diameters of 80 nm and lengths of 20 μm, which are equivalent to the pore size and thickness of Kapton foils. The nanowires exhibit a preferential orientation along the {110} plane with a composition of 11.26 at.% Bi, 26.23 at.% Sb, and 62.51 at.% Te. Temperature dependence studies of the electrical resistance show the semiconducting nature of the nanowires with a negative temperature coefficient of resistance and band gap energy of 0.089 ± 0.006 eV.

Direct lyotropic liquid crystalline templating has been successfully applied to produce nanostructured IV–VI semiconductor PbTe thin films by electrodeposition both on gold and n-type (1 0 0) silicon substrates. The PbTe films were characterized by transmission electron microscopy, X-ray diffraction and polarized optical microscopy and the results show that the films have a regular hexagonal nanoarchitecture with a high crystalline rock salt structure and exhibit strong birefringence. The optical absorption measurements using Fourier transform infrared spectroscopy show that the nanostructured PbTe films have a direct band gap of 0.37 eV.

Nanostructured CdTe films were electrodeposited on CdS substrates from lyotropic liquid crystalline phases of non-ionic surfactants using citric acid. The deposition mechanism was studied using cyclic voltammetry. The effect of citric acid on the deposition properties of CdTe was investigated. The CdTe films were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, polarized optical microscopy, and UV–vis spectroscopy. In addition quartz crystal microbalance studies were carried out to provide further evidence for the mesoporosity of the CdTe films. The results indicated that the films exhibited a mesoporous structure and good optical properties.

Direct liquid crystal templating from non-ionic polyoxyethylene surfactants has been utilised to produce well-defined birefringent films of nanostructured cadmium telluride films which displayed good optical properties as evidenced by UV/VIS reflectance spectroscopy.

•New concept for nanostructuring thermoelectric materials based on inverse lipid cubic phases.•3D nanostructure of bismuth telluride reported is composed of interconnected bismuth telluride nanowires with diameters from 6–15 nm.•Our method produces freestanding nanowire networks of a thermoelectric semiconductor at room temperature connected to an electrode surface.•Preliminary thermoelectric measurements indicate a higher Seebeck coefficient for nanostructured bismuth thin telluride.We report a novel route to the fabrication of 3D nanostructured stoichiometric bismuth telluride (Bi2Te3) films by electrodeposition through inverse lipid cubic phases as evidenced by Small-angle X-ray Scattering (SAXS) and Helium Ion Microscopy (HIM). The nanostructured Bi2Te3 films were composed of interconnected nanowires with diameters of 60–150 Å.

High density p-type Bi0.5Sb1.5Te3nanowire arrays are produced by a combination of electrodeposition and ion-track lithography technology. Initially, the electrodeposition of p-type Bi0.5Sb1.5Te3 films is investigated to find out the optimal conditions for the deposition of nanowires. Polyimide-based Kapton foils are chosen as a polymer for ion track irradiation and nanotemplating Bi0.5Sb1.5Te3nanowires. The obtained nanowires have average diameters of 80 nm and lengths of 20 μm, which are equivalent to the pore size and thickness of Kapton foils. The nanowires exhibit a preferential orientation along the {110} plane with a composition of 11.26 at.% Bi, 26.23 at.% Sb, and 62.51 at.% Te. Temperature dependence studies of the electrical resistance show the semiconducting nature of the nanowires with a negative temperature coefficient of resistance and band gap energy of 0.089 ± 0.006 eV.

Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi2Te3) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi2Te3 films with a high Seebeck coefficient of up to −200 μV K−1 and a high electrical conductivity of up to 400 S cm−1 resulting in a power factor of 1.6 × 10−3 W m−1 K−2 at film growth rates of 100 μm h−1 for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD.