Growth of Anodic Aluminum Oxide Templates and the Application in Fabrication of the BiSbTe-Based Thermoelectric Nanowires

A two-step electrochemical anodization was used to form the anodic aluminum oxide (AAO) thin films with nanotube arrays of self-organized honeycomb structure. Al foil was anodized in 10% sulfuric acid (H2SO4) and 3% oxalic acid (H2C2O4) at 25°C at constant voltage of 40 V for 60 min for two times. Ethylene glycol (C2H6O2) was used as a solution and 0.3 M potassium iodide (KI) was used to improve the solution’s conductivity. Different electrolyte concentrations of Bi(NO3)3-5H2O, SbCl3, and TeCl4were added into KI-C2H6O2solution and the cyclic voltammetry experiment was used to find the reduced voltages of Bi3+, Sb3+, and Te4+ions. The potentiostatic deposition and pulse electrodeposition (PED) processes were used to deposit the (Bi,Sb)2−xTe3+x-based materials. Field-emission scanning electron microscope and energy dispersive spectrometers were used to analyze the compositions of the deposited (Bi,Sb)2−xTe3+x-based materials. After finding the optimal deposition parameter of the PED process the AAO nanotube arrays were used as the templates to deposit the (Bi,Sb)2−xTe3+x-based thermoelectric nanowires.