Impact of annealing on charge storage capability of thermally evaporated molybdenum oxide thin films

Abstract

Rapid technological advancements in recent years have necessitated the creation of energy-related devices. Due to their unique properties, including an exceptional cycling life, safe operation, low processing cost, and a higher power density than batteries, supercapacitors (SCs) have been identified as one of the most promising candidates to meet the demands of human sustainability. To increase the energy density of SCs, several advanced electrode materials and cell designs have been researched during the past few years. Utilizing the Faradaic charge storage process of transition metal cations, transition metal compounds have recently received attention as prospective electrode materials for SCs with high energy densities. In this work, the structure, morphology and electrochemical properties of molybdenum oxide (MoO3) films deposited via thermal evaporation technique and annealed at various temperatures were systematically investigated in order to examine the potential use of MoO3 for supercapacitors. Electrochemical analysis confirmed the pseudocapacitance characteristics of the synthesized films. The annealing temperature affects the oxidation and reduction observed in the cyclic voltammetry (CV) plots. Areal capacitance of thin films annealed at 150[Formula: see text]C was found to be maximum and this could be attributed to the formation of hollow tube-like nanostructures which provided more active sites, than films annealed at higher temperatures. This also influences the charge storage ability of the synthesized films. It would be logical to assume that additional research in this area will result in more interesting discoveries and, eventually, the vi-ability of those promising Mo-based compounds in high-tech energy storage systems.