Investigations On The Electrodeposition Mechanisms And Preparation Technology Of P-type Bi_xSb_2-xTe₃ Thermoelectric Material In H₂SO₄ Solution

In recent years,with the deepening energy crisis and the increasing environmental pollution,the demand for environmental energy is more and more urgent.Thermoelectric materials can convert heat to electricity,which provides an effective way to look for alternative energy to reduce dependence on fossil fuels and greenhouse gas emissions.So far,Bi₂Te₃-based compounds are still considered to be the best thermoelectric materials at room temperature,such as p-type Bi_xSb_2-xTe₃materials.p-type Bi_xSb_2-xTe₃ materials have been widely used in the field of thermoelectric generators,because of its superior thermoelectric performances.In this article we investigated the electrochemical behaviors of Bi,Sb and Te on Au electrode in sulfuric acid solution by cyclic voltammetry?CV?and AC impedance spectra?EIS?.On the basis,investigate the effects of deposition potentials,solution temperatures,concentrations of ions,pH values on the morphologies and compositions of Bi-Sb-Te materials prepared by potentiostatic method.The optional technique of depositing Bi_0.5Sb_1.5Te₃ materials was established.The morphologies,compositions and structures of Bi-Sb-Te materials deposited were analyzed by SEM,EDS and XRD.And the seebeck coefficient and resistivity were tested.The results show that the addition of CMS and CZT increased the solubility and stability of Bi,Sb,Te in sulfuric acid solution.And the deposition potentials of three kinds of ions close to each other,which are beneficial to the codeposition of Bi,Sb,Te.The reduction processes of three kinds of elements are conducted step by step and reduction processes are irreversible.During the potentiostatic deposition process,deposition potentials,solution temperatures,concentrations of ions and pH values had effects on the morphologies and compositions of Bi-Sb-Te materials deposited.The optional technique of depositing Bi_0.5Sb_1.5Te₃ films materials as follows:The concentration of Bi,Sb,Te in the solution were 0.015 M,0.05 M,0.004 M respectively.pH value of the solution was 0.5.The temperature of the solution is 20?,and the deposition potential was-0.11 V.The seebeck coefficient and resistivity were up to 126?V/K,3.23×10^-5?·m^-1,respectively.