Tuning the Geometrical and Crystallographic Characteristics of Bi₂Te₃ Nanowires by Electrodeposition in Ion-Track Membranes

Abstract

We report the fabrication of Bi 2 Te 3 nanowires with diameters as small as 15 nm, which is comparable to the size theoretically estimated for the onset of improvement of the thermoelectric figure of merit ZT by quantum-size effects. The versatility of the template-assisted growth, combining self-prepared ion-track etched membranes and electrochemical deposition, has been employed to synthesize Bi 2 Te 3 nanowires with controlled diameters in 10, 30, and 60 μm thick membranes and with large aspect ratios (length over diameter) of up to 1000. SEM, HRTEM, and XRD investigations reveal how morphology, surface roughness, and crystalline orientation of the Bi 2 Te 3 nanowires depend on deposition potential, temperature, and channel diameter.

A novel route to nanostructured bismuth telluride films by electrodeposition

“…Alternatively polymeric membranes with low thermal conductivities (e.g. 0.21 W mK -1 for polycarbonate) have also been employed as nanotemplates for bismuth telluride nanowire growth [8][9][10][11]. Polycarbonate templates can be removed with solvents such as dichloromethane or dimethylformanide, however freestanding nanowires with an aspect ratio of 10 or higher will collapse [7].…”

Individual thermoelectric properties of electrodeposited bismuth telluride nanowires in polycarbonate membranes

“…High-density Bi 2 Te 3 NWs are predominantly synthesized by a number of template-assisted methods using track-etched membranes [20][21][22], diblock copolymers [23,24], or anodized aluminum oxide (AAO) templates [25,26]. Of these, AAO templates have found particularly widespread usage owing to the simplicity and flexibility of their fabrication methods.…”

Template-based syntheses for shape controlled nanostructures

“…Similar improvements in the zT of chalcogenides such as Bi 2 Te 3 and Bi x Sb 2 − x Te 3 , some of the best bulk thermoelectric materials, have also been modeled [385,386] and demonstrated experimentally [387,388]. These materials may be readily grown in nanowire morphology via templated electrodeposition [387,[389][390][391][392][393], with Bi 2 Te 3 nanowires also having been grown via galvanic displacement on DNA templates [394]. Increased zT has also been demonstrated in superlattice structures, such as PbTe/Te, PbTe/PbSe [395], and Bi 2 Te 3 [396] superlattice structures may be combined with nanowire morphologies via templated electrodeposition for potentially even greater gains in zT.…”

“…Instead, a trend toward larger pore MSNs, HMSNs, and other pore-expanded MSNs that are capable of delivering larger compounds for genetic or peptide therapy applications have been shown to be more effective in targeting cancer resistant cells [462]. With pore expansion techniques, as those mentioned earlier with TMB, delivery of larger proteins [383,[463][464][465] and even genetic material [207,391] are possible.…”