Electrochemical performance of Bi2Te3 heterostructure thin film and Cu7Te4 nanocrystals on undoped and In3+-doped WO3 films for energy storage applications

Abstract

We demonstrated the synthesis of undoped and In3+-doped WO3 as an electron acceptor for energy storage applications, by utilizing the electrochemical S2− insertion/extraction process at the heterostructure of rhombohedral Bi2Te3 thin films and hexagonal Cu7Te4 nanocrystals. The cyclic voltammetry of heterostructured electrodes with and without In3+ doping both showed Faradic pseudo-capacitance behavior based on the oxidation and reduction processes. The largest exchange current density of 3.43 mA/cm2 was obtained for the heterojunction-structured-Bi2Te3 thin films and Cu7Te4 nanocrystals with In3+ doping in the WO3 electrode. This implies more favorable hydrogen evolution reaction kinetics and higher electrocatalytic activity at the anode. The highest specific capacity of 90.2 mA h/g was obtained at a scan rate of 10 mV/s, with the power density reaching 1.7 kW/kg at the highest energy density value of 18.85 Wh/kg for the In3+-doped electrode. The overall results revealed the inherent properties of the new electrode materials, as well as their potential use in energy storage devices or in future electrochemical energy conversion and storage applications involving hydrogen (or oxygen) evolution reactions.